Immunocytochemical localization and determination of hormone-induced synthesis of the sulfated oviductal glycoproteins

Recombinant human OVGP1 increases intracellular calcium and further potentiates the effects of progesterone on human sperm

Purpose

To investigate the effects of recombinant human oviduct–specific glycoprotein (rHuOVGP1) alone and in combination with progesterone (P4) on intracellular Ca²⁺ concentration [Ca²⁺]_i and to investigate if rHuOVGP1 in combination with P4 can further enhance tyrosine phosphorylation (pY) of sperm proteins during human sperm capacitation.

Methods

Fluorometric flow cytometry was performed to examine the effects of rHuOVGP1 on [Ca²⁺]_i in human sperm during capacitation. Confocal microscopy was used in conjunction with live cell imaging to analyze the influence of rHuOVGP1 and P4 on [Ca²⁺]_i in the sperm tail and to examine the involvement of CatSper channels in their effect on [Ca²⁺]_i. Western blot analysis was performed to assess the protein levels of p105, a major tyrosine-phosphorylated sperm protein.

Results

rHuOVGP1 increases [Ca²⁺]_i in human sperm at the beginning of capacitation and further increases and sustains the level of [Ca²⁺]_i in the sperm tail following the addition of P4. Inhibition of CatSper channels impedes the effects of rHuOVGP1 on [Ca²⁺]_i in the sperm tail. P4 alone can increase pY of a major human sperm protein, p105, yet yields a further increase when used in combination with rHuOVGP1.

Conclusion

The present study revealed that rHuOVGP1 may work with P4 to upregulate [Ca²⁺]_i at the beginning of capacitation in part through CatSper channels which, in turn, leads to the downstream event of pY of sperm proteins and enhancement of sperm capacitation.

Supplementary information

The online version contains supplementary material available at 10.1007/s10815-022-02591-0.

The role of oviduct-specific glycoprotein (OVGP1) in modulating biological functions of gametes and embryos

Diverse lines of evidence indicate that the mammalian oviduct makes important contributions to the complex process of reproduction other than being simply a conduit for the transport of gametes and embryos. The cumulative synthesis and transport of proteins secreted by oviductal secretory cells into the oviductal lumen create a microenvironment supporting important reproductive events, including sperm capacitation, fertilization, and early embryo development. Among the components that have been identified in the oviductal fluid is a family of glycosylated proteins known collectively as oviduct-specific glycoprotein (OVGP1) or oviductin. OVGP1 has been identified in several mammalian species, including humans. The present review summarizes the work carried out, in various mammalian species, by many research groups revealing the synthesis and secretion of OVGP1, its fate in the female reproductive tract upon secretion by the oviductal epithelium, and its role in modulating biological functions of gametes and embryos. The production and functions of recombinant human OVGP1 and recombinant OVGP1 of other mammalian species are also discussed. Some of the findings obtained with immunocytochemistry will be highlighted in the present review. It is hoped that the findings obtained from recent studies carried out with recombinant OVGP1 from various species will rekindle researchers’ interest in pursuing further the role of the oviductal microenvironment, of which OVGP1 is a major component, in contributing to the successful occurrence of early reproductive events, and the potential use of OVGP1 in improving the current assisted reproductive technology in alleviating infertility.

Fatty Acid Profile of Blood Plasma at Mating and Early Gestation in Rabbit

The aim of this study was to analyse the fatty acid (FA) profile of blood plasma at mating and 72 hpm by gas chromatography. Moreover, the correlation between FA and ovulation rate, normal embryos and compacted morulae was estimated. Palmitic, linoleic, oleic and stearic were the highest FA concentrations at mating and 72 hpm. Most long chain saturated and PUFA were higher at 72 hpm than at mating, while MUFA were higher at mating. SFA, MUFA and PUFA were high and positively correlated. Correlation was 0.643 between MUFA at mating and ovulation rate, and 0.781 between MUFA and normal embryos, respectively. Compacted morulae were slightly correlated with SFA at mating (0.465). In conclusion, the FA profile of plasma varies depending on the reproductive cycle of the rabbit female, adapting to energetic requirements at mating and early gestation. Moreover, positive correlations are found between fatty acids and ovulation rate and embryo development and quality.

A Comparative View on the Oviductal Environment during the Periconception Period

The oviduct plays important roles in reproductive events: sperm reservoir formation, final gamete maturation, fertilization and early embryo development. It is well known that the oviductal environment affects gametes and embryos and, ultimately, the health of offspring, so that in vivo embryos are better in terms of morphology, cryotolerance, pregnancy rates or epigenetic profile than those obtained in vitro. The deciphering of embryo-maternal interaction in the oviduct may provide a better understanding of the embryo needs during the periconception period to improve reproductive efficiency. Here, we perform a comparative analysis among species of oviductal gene expression related to embryonic development during its journey through the oviduct, as described to date. Cross-talk communication between the oviduct environment and embryo will be studied by analyses of the secreted or exosomal proteins of the oviduct and the presence of receptors in the membrane of the embryo blastomeres. Finally, we review the data that are available to date on the expression and characterization of the most abundant protein in the oviduct, oviductin (OVGP1), highlighting its fundamental role in fertilization and embryonic development.

Porcine oviductal extracellular vesicles interact with gametes and regulate sperm motility and survival

Once in the female reproductive tract, spermatozoa undergo several modifications to acquire their complete fertilizing ability. Interactions between the oviductal fluid (OF) and gametes contribute to a successful fertilization. Recently, oviductal extracellular vesicles have been identified as an important part of the OF but their interactions with gametes are not fully understood. In the present study, we aim at determining the patterns of interactions between porcine oviductal extracellular vesicles (poEVs) and gametes (spermatozoa and oocytes). Moreover, we evaluate the effect of poEVs on sperm survival and motility to better understand the mechanisms by which poEVs modulate the processes leading to fertilization. Evaluation of poEVs uptake by spermatozoa showed that poEVs bind to spermatozoa in a time and dose dependent manner. Co-incubation of spermatozoa with poEVs (0.2 μg/μL) increased fresh and frozen sperm survival after 6 and 17 h, respectively. By contrast, poEVs supplementation reduced the total and progressive sperm motility after 2 h. Additionally, we demonstrated that poEVs interacted with the cumulus cells, zona pellucida (ZP) and oocyte, being able to cross the ZP. Besides, we showed that poEVs delivered their cargo into the oocyte, by the transfer of OVGP1 protein. In conclusion, our results demonstrated that poEVs are able to interact with both gametes. Besides, the findings from the present study showed that poEVs may participate in maintaining sperm viability and reducing motility, functions associated with the oviduct sperm reservoir. Although further investigations are needed, our results indicate that poEVs can be a potential tool to improve sperm life span during sperm handling and enhance IVF outcomes.

Human OVGP1 enhances tyrosine phosphorylation of proteins in the fibrous sheath involving AKAP3 and increases sperm-zona binding

Purpose

To investigate if the recombinant human oviduct-specific glycoprotein (rHuOVGP1)–enhanced tyrosine-phosphorylated (pY) proteins are components of specific structure(s) of the sperm tail and if rHuOVGP1 binds to the oocyte and enhances sperm-egg binding.

Methods

Immunofluorescent staining and confocal microscopy were performed to examine the localization of pY proteins, outer dense fiber (ODF), and A-Kinase Associated Protein 3 (AKAP3) in human sperm during capacitation. Western blot and immunoprecipitation were employed to analyze protein levels of pY proteins and AKAP3. Immunofluorescent staining was performed to examine the binding of rHuOVGP1 to human oocytes. The effect of rHuOVGP1 on enhancing sperm-zona binding was examined using hemizona assay.

Results

pY proteins were detected mainly in the fibrous sheath (FS) surrounding the ODF with a relatively weak immunoreaction in the neck and mid-piece. Western blot analysis revealed co-migration of the pY 105 kDa protein with AKAP3, which was further confirmed by immunoprecipitation correlating immunofluorescent results of co-localization of pY proteins with AKAP3 in the sperm tail. rHuOVGP1 binds specifically to the zona pellucida (ZP) of human oocytes. Prior incubation of sperm and/or ZP with rHuOVGP1 increased sperm-egg binding.

Conclusions

The present study revealed that one of the major rHuOVGP1-enhanced pY proteins could be AKAP3 of the FS and that rHuOVGP1 is capable of binding to human ZP and its presence in the medium results in an increase in sperm-zona binding. Supplement of rHuOVGP1 in in vitro fertilization media could be beneficial for enhancement of the fertilizing ability of human sperm.

Effect of recombinant and native buffalo OVGP1 on sperm functions and in vitro embryo development: a comparative study

Background

An oviduct- specific glycoprotein, OVGP1, is synthesized and secreted by non-ciliated epithelial cells of the mammalian oviduct which provides an essential milieu for reproductive functions. The present study reports the effects of recombinant buffalo OVGP1 that lacks post-translational modifications, and native Buffalo OVGP1 isolated from oviductal tissue, on frozen- thawed sperm functions and in vitro embryo development.

Results

The proportion of viable sperms was greater (P < 0.05) in the recombinant OVGP1-treated group compared to the native OVGP1-treated group at 2 h, 3 h, and 4 h of incubation. The proportion of motile sperms at 3 h and 4 h of incubation; and membrane- intact sperms at 4 h was greater (P < 0.05) in the native OVGP1-treated group compared to the control and recombinant OVGP1-treated groups. The proportion of capacitated and acrosome- reacted sperms was greater (P < 0.05) in the native OVGP1-treated group compared to the recombinant OVGP1 group at 4 h. The rates of cleavage of embryos and their development to the blastocyst stage were greater (P < 0.05) in the presence of either native or recombinant OVGP1 in comparison to control at 10 μg/mL concentration as compared to 5 or 20 μg/mL.

Conclusions

The study suggests that both native and recombinant OVGP1 impart a positive effect on various sperm features and in vitro embryo development. However, native OVGP1 was found to have a more pronounced effect in comparison to recombinant non-glycosylated OVGP1 on various sperm functions except viability. Hence, our current findings infer that glycosylation of OVGP1 might be essential in sustaining the sperm functions but not the in vitro embryo development.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0201-5) contains supplementary material, which is available to authorized users.

Recombinant human oviductin regulates protein tyrosine phosphorylation and acrosome reaction

The mammalian oviduct synthesizes and secretes a major glycoprotein known as oviductin (OVGP1), which has been shown to interact with gametes and early embryos. Here we report the use of recombinant DNA technology to produce, for the first time, the secretory form of human OVGP1 in HEK293 cells. HEK293 colonies stably expressing recombinant human OVGP1 (rHuOVGP1) were established by transfecting cells with an expression vector pCMV6-Entry constructed with OVGP1 cDNA. Large quantities of rHuOVGP1 were obtained from the stably transfected cells using the CELLSPIN cell cultivation system. A two-step purification system was carried out to yield rHuOVGP1 with a purity of >95%. Upon gel electrophoresis, purified rHuOVGP1 showed a single band corresponding to the 120–150 kDa size range of human OVGP1. Mass spectrometric analysis of the purified rHuOVGP1 revealed its identity as human oviductin. Immunofluorescence showed the binding of rHuOVGP1 to different regions of human sperm cell surfaces in various degrees of intensity. Prior treatment of sperm with 1% Triton X-100 altered the immunostaining pattern of rHuOVGP1 with an intense immunostaining over the equatorial segment and post-acrosomal region as well as along the length of the tail. Addition of rHuOVGP1 in the capacitating medium further enhanced tyrosine phosphorylation of sperm proteins in a time-dependent manner. After 4-h incubation in the presence of rHuOVGP1, the number of acrosome-reacted sperm induced by calcium ionophore significantly increased. The successful production of rHuOVGP1 can now facilitate the study of the role of human OVGP1 in fertilization and early embryo development.

Recombinant hamster oviductin is biologically active and exerts positive effects on sperm functions and sperm-oocyte binding

Studies carried out in several mammalian species suggest that oviductin, also known as oviduct-specific glycoprotein or OVGP1, plays a key role in sperm capacitation, fertilization, and development of early embryos. In the present study, we used recombinant DNA technology to produce, for the first time, recombinant hamster OVGP1 (rHamOVGP1) in human embryonic kidney 293 (HEK293) cells. rHamOVGP1 secreted in the culture medium was purified by affinity chromatography. The resulting protein migrated as a poly-dispersed band of 160-350 kDa on SDS-PAGE corresponding to the molecular mass of the native HamOVGP1. Subsequent mass spectrometric analysis of the purified rHamOVGP1 confirmed its identity as HamOVGP1. Immunocytochemistry demonstrated binding of rHamOVGP1 to the mid-piece and head of hamster sperm and to the zona pellucida (ZP) of ovarian oocytes. In vitro functional experiments showed that addition of rHamOVGP1 in the capacitation medium further enhanced tyrosine phosphorylation of two sperm proteins of approximately 75 kDa and 83 kDa in a time-dependent manner. After 3 hours of incubation in the presence of rHamOVGP1, a significant increase in acrosome reaction was measured. Pretreatment of either sperm or oocyte with 20 μg/ml of rHamOVGP1 prior to sperm-egg binding assay significantly increased the number of sperm bound to the ZP. Addition of rHamOVGP1 in the medium during sperm-egg binding with either oocyte or sperm pretreated with rHamOVGP1 also saw an increase in the number of sperm bound to ZP. In all experimental conditions, the effect of rHamOVGP1 on sperm-oocyte binding was negated by the addition of monoclonal anti-HamOVGP1 antibody. The successful production and purification of a biologically active rHamOVGP1 will allow further exploration of the function of this glycoprotein in reproductive function.

[Use of an in vitro model in bovine to evidence a functional and molecular dialogue between preimplantation embryo and oviduct epithelial cells]

Beyond being a pipe between ovary and uterus, the oviduct is an active player in different aspects of early reproductive processes, in particular in the transport of embryos to the site of implantation and the regulation of its early development. Different studies evidenced a communication between oviduct and early embryo at the molecular and functional levels. Since the study of these interactions is difficult in vivo, different in vitro systems have been developed to mimic the maternal milieu during early development. These systems allowed to confirm the action of the cells on the quality of early development (blastocyst rate and viability). In turn, the embryos are producing signals that are able to modify and adapt the activity of maternal cells.

Purification, sequence characterization and effect of goat oviduct-specific glycoprotein on in vitro embryo development

Oviduct-specific glycoprotein (oviductin) plays an important role during fertilization and early embryonic development. The oviductin cDNA was successfully cloned and sequenced in goat, which possessed an open reading frame of 1620 nucleotides representing 539 amino acids. Predicted amino acid sequence showed very high identity with sheep (97%) followed by cow (94%), porcine (77%), hamster (69%), human (66%), rabbit (65%), mouse (64%) and baboon (62%). The bioinformatics analysis of the sequences revealed the presence of a signal sequence of 21 amino acids, one potential N-linked glycosylation site at position 402, 21 potential O-linked glycosylation sites and 36 potential phosphorylation sites. The native oviductin was purified from the oviductal tissue, which showed three distinct bands on SDS-PAGE and western blot (MW ~60-95 kDa). The predicted molecular weight of goat oviductin was 57.5 kDa, calculated from the amino acid sequences. The observed higher molecular weight has been attributed to the presence of large number of potential O-linked glycosylation sites. The lower concentration (10 μg/mL) of oviductin increased the cleavage rate, morula and blastocyst yield significantly (P < 0.05) as compared to higher concentration (100 μg/mL). Goat oviductin retarded the activity of pronase (0.1%) on zona solubility of oocytes significantly (P < 0.01).

Mouse oviduct-specific glycoprotein is an egg-associated ZP3-independent sperm-adhesion ligand

Mouse sperm-egg binding requires a multiplicity of receptor-ligand interactions, including an oviduct-derived, high molecular weight, wheat germ agglutinin (WGA)-binding glycoprotein that associates with the egg coat at ovulation. Herein, we report the purification and identification of this sperm-binding ligand. WGA-binding, high molecular weight glycoproteins isolated from hormonally primed mouse oviduct lysates competitively inhibit sperm-egg binding in vitro. Within this heterogeneous glycoprotein preparation, a distinct 220 kDa protein selectively binds to sperm surfaces, and was identified by sequence analysis as oviduct-specific glycoprotein (OGP). The sperm-binding activity of OGP was confirmed by the loss of sperm-binding following immunodepletion of OGP from oviduct lysates, and by the ability of both immunoprecipitated OGP and natively purified OGP to competitively inhibit sperm-egg binding. As expected, OGP is expressed by the secretory cells of the fimbriae and infundibulum; however, in contrast to previous reports, OGP is also associated with both the zona pellucida and the perivitelline space of mouse oocytes. Western blot analysis and lectin affinity chromatography demonstrate that whereas the bulk of OGP remains soluble in the ampullar fluid, distinct glycoforms associate with the cumulus matrix, zona pellucida and perivitelline space. The sperm-binding activity of OGP is carbohydrate-dependent and restricted to a relatively minor peanut agglutinin (PNA)-binding glycoform that preferentially associates with the sperm surface, zona pellucida and perivitelline space, relative to other more abundant glycoforms. Finally, pretreatment of two-cell embryos, which do not normally bind sperm, with PNA-binding OGP stimulates sperm binding.

Expression of human oviductin in an immortalized human oviductal cell line

OBJECTIVE

To determine whether OE-E6/E7, an immortalized human oviductal epithelial cell line, expresses oviductin messenger RNA (mRNA) and its translated protein.

DESIGN

Transmission electron microscopy was employed to characterize the morphology of OE-E6/E7 cells followed by reverse-transcription polymerase chain reaction (PCR) analysis of oviductin mRNA and sequencing of the nested-PCR product. Confocal microscopy was used, using a polyclonal antibody against human oviductin and Con A as a marker for mannose residues, to reveal the colocalization of human oviduct-specific glycoprotein with the endoplasmic reticulum and Golgi compartments.

SETTING

University-based anatomy and cell biology department.

PATIENT(S)

Women undergoing laparoscopy for tubal ligation or hysterectomy due to uterine fibroma.

INTERVENTION(S)

An immortalized OE-E6/E7 cell line was previously established using human oviductal epithelial cells. Electron microscopy, RT-PCR, sequencing, immunohistochemistry and confocal microscopy were performed.

MAIN OUTCOME MEASURE(S)

The presence of human oviductin mRNA and protein in OE-E6/E7 cells.

RESULT(S)

OE-E6/E7 cells retain morphological features characteristic of secretory cells and express human oviductin mRNA and its translated protein.

CONCLUSION(S)

OE-E6/E7 cells were characterized for the first time by electron microscopy and shown to exhibit histological features typical of secretory cells. Reverse-transcription PCR with sequencing and confocal microscopy showed, respectively, that human oviductin mRNA and protein are expressed in OE-E6/E7 cells. Our results suggest that OE-E6/E7 could be a useful tool for future studies of the function of human oviductin.

Detection of glycosyltransferases in the golden hamster (Mesocricetus auratus) oviduct and evidence for the regulation of O-glycan biosynthesis during the estrous cycle

Recently, we provided evidence that the glycosylation of hamster oviductin, a member of the mucin family of glycoproteins, is regulated during the estrous cycle. In order to further elucidate the glycosylation process of oviductal glycoproteins, we identified biosynthetic pathways involved in the assembly of mucin-type O-linked oligosaccharide (O-glycan) chains in the hamster oviduct. Our results demonstrated that the hamster oviduct has high activities of glycosyltransferases that synthesize O-glycans with core 1, 2, 3 and 4 structures as well as elongated structures. Oviduct therefore represents a typical mucin-secreting tissue. Our results also showed that specific glycosyltransferase activities are regulated during the estrous cycle. Mucin-type core 2 beta6-GlcNAc-transferase (C2GnT2) is responsible for synthesizing core 2 and core 4 structures in the oviduct. Specific assays for C2GnT2 revealed a cyclical pattern throughout the estrous cycle with high activity at the stages of proestrus and estrus and low activity at diestrus 1. Using semiquantitative RT-PCR, the mRNA levels for C2GnT2 in the estrous cycle stages could be correlated with the enzyme activities. An increase in glycosyltransferase activity in the hamster oviduct at the time of ovulation suggests that glycosylation of oviductal glycoproteins may be necessary for these proteins to exert their functions during the process of fertilization.

Evidence for the role of oviduct secretions in sperm function, fertilization and embryo development

The oviduct is a dynamic organ which facilitates gamete function, fertilization and embryo development. Secretions of the oviduct, recovered by tissue culture or cannulation techniques have been used to define the composition of the oviduct milieu, as well as functions associated with stage of the reproductive cycle or region of the oviduct. Several oviduct proteins have been shown to associate with the gametes and embryos. Ongoing studies are directed at identifying oviduct proteins and determining their function. Oviduct-specific glycoproteins (OSG) have been purified from the oviduct and shown in vitro to have positive affects on sperm capacitation, sperm-ovum binding, ovum penetration and embryo development. Osteopontin, another oviduct secretion, also has been shown to stimulate fertilization and embryo development. The picture emerging is that some components of the oviduct milieu have overlapping functions to collectively provide a failsafe system to ensure fertility in vivo so that success is not dependent on a single component.

Oviduct-specific glycoprotein modulates sperm-zona binding and improves efficiency of porcine fertilization in vitro

Oviduct-specific glycoprotein (OGP) displays estrus-associated regional and temporal differences in expression and localizes to the zona pellucida, perivitelline space, and plasma membrane of oviductal oocytes and embryos, suggesting that it may have a role in regulation of fertilization and/or early embryonic development. The aims of this study were to evaluate the effect of exogenous OGP on in vitro fertilization (IVF) and embryo development in the pig using a defined serum-free culture system. In vitro-matured porcine oocytes were incubated with homologous OGP (0, 1, 10, 20, and 40 microg/ml) for 3 h and then washed prior to IVF. Exposure of oocytes to 10 or 20 microg/ml porcine OGP (pOGP) significantly reduced the incidence of polyspermy compared with the control (P < 0.01) while maintaining high penetration rates. When oocytes, spermatozoa, or both were preincubated with 10 microg/ml pOGP prior to IVF, the incidence of polyspermy was similarly reduced (P < 0.01) by all three treatments without affecting penetration rates. The ability of spermatozoa to undergo calcium ionophore-induced acrosome reaction was similar with or without exposure to pOGP. However, significantly fewer spermatozoa (P < 0.01) bound to the zona pellucida when oocytes were preincubated with pOGP. To evaluate the effect of pOGP on embryo development, embryos were cultured in pOGP-supplemented medium for 48 h or 144 h. Both transient and continuous exposure to pOGP significantly enhanced cleavage and blastocyst formation rate compared with the control (P < 0.01). These data demonstrate that exposure of either in vitro-matured oocytes or spermatozoa to pOGP decreased polyspermy and spermatozoa binding while maintaining high penetration rates of pig oocytes fertilized in vitro. Furthermore, pOGP exerted an embryotrophic effect independent of effects demonstrated on spermatozoa and oocytes at fertilization.

Variable expression of oviductin mRNA at different stages of human reproductive cycle

PURPOSE

To examine the in vivo expression of oviductin mRNA at different stages of the human female reproductive cycle including pregnancy and after menopause.

METHODS

Oviducts were obtained from 25 women in normal menstrual cycle, 5 in early pregnancy, 5 undergoing postpartum sterilization, and 4 menopausal women. The oviductal mucosal tissue was isolated and oviductin mRNA was assessed using reverse-transriptase-polymerase chain reaction (RT-PCR); its correlation with various hormones was assessed.

RESULTS

Oviductin mRNA was detected throughout the menstrual cycle, highest in the periovulatory period. It continued to be expressed in early pregnancy but was absent in the postpartum period and after menopause.

CONCLUSIONS

The production and function of oviductin at different stages of human reproductive cycle including pregnancy is not well known. Its highest expression at the time of ovulation is consistent with a supportive role in fertilization and early embryo development.

Influence of ovine oviducal amino acid concentrations and an ovine oestrus-associated glycoprotein on development and viability of bovine embryos

This study examined the effects of incorporating an ovine oviducal oestrus-associated glycoprotein (oEGP) and amino acids, at the concentrations present in the ovine oviduct around the time of oestrus, on in vitro production and subsequent viability of bovine embryos. The first experiment compared the influence of ovine oviducal concentrations of amino acids with MEM and BME amino acids. There was no treatment effect on cleavage rate (74.9% vs. 75.5%), but there was a higher (P < 0.05) blastocyst yield (30.4 vs. 25.2) and a shorter time (P < 0.05) to blastocyst formation (7.16 +/- 0.64 vs. 7.27 +/- 0.56 days) following use of oviducal concentrations of amino acids. Experiment 2 examined the influence of oEGP in combination with each of the amino acid treatments. oEGP had no effect on cleavage or blastocyst yield within amino acid treatments. Day of blastocyst formation significantly influenced nuclei numbers (P < 0.001) with higher numbers being obtained on day 7 than on either day 6 or day 8. There was also a significant (P < 0.01) interaction between day of blastocyst formation and amino acid treatment on blastocyst nuclei numbers. The third experiment studied the effects of the amino acid treatments on embryo viability. There was no effect of amino acid treatment of embryos on pregnancy rates (34.5 vs. 44.4%) following transfer of days 6 and 7 blastocysts to synchronized recipients. oEGP did not influence any of the parameters of bovine embryo development that were measured, suggesting that effects of this protein observed on ovine embryos are species specific. It is concluded that ovine oviducal amino acid concentrations are beneficial to blastocyst development in vitro but do not have any further beneficial effect following transfer of blastocysts to recipients.

Functions of proteins secreted by oviduct epithelial cells

Studies on embryonic development in vitro as well as observations in vivo, suggested that two aspects of oviduct physiology are important for early development. On one side has to be considered the oviduct "environment": temperature, pH, osmotic pressure, nutrients, oxygen tension, free radical scavengers, etc. On the other, the oviduct "active components": stimulatory and/or regulatory molecules, supposed to finely regulate the fertilisation process and the first differentiative steps. While the physical environment of the oviduct has been under investigation for some decades, studies on oviduct-specific molecules and their functions have only been developed much more recently. The amount of information on this topic, however, has rapidly reached the size that demands a summary. In this review the descriptive literature on oviduct specific proteins will be examined as a basis for illustrating the possible functions of these molecules. In particular their role in fertilisation and early embryonic cleavages will be analysed in some details. Finally a section is devoted to the presence and physiological significance of growth factors in oviduct fluid.

A human oviduct-specific glycoprotein: synthesis, secretion, and localization during the menstrual cycle

The major objective of this study was to examine the hormonal regulation of a human oviduct-specific glycoprotein (huOGP) throughout the menstrual cycle and in all regions of the human oviduct. Regulation of synthesis and secretion was examined at both the protein (Western immunoblots and immunocytochemistry) and mRNA (Northern and slot blots) levels and correlated with changes in the morphological features of the oviductal epithelial cells throughout the cycle. Immunoblot analysis of oviductal fluid and explant culture media from all regions of the oviduct demonstrated that huOGP is primarily found during the follicular stage of the cycle and is not present in serum, follicular fluid, or uterine endometrium. Moreover, two-dimensional (2-D) immunoblots showed that all major isoelectric variants of huOGP observed on 2-D fluorographs are immunologically related. Light microscopic immunocytochemistry localized huOGP to oviductal secretory cells in both ampulla and isthmic regions, with the most intense immunoperoxidase staining seen in midcycle samples. Using an indirect immunogold technique at the electron microscopic level, huOGP was specifically localized to secretory granules of the ampullary and isthmic nonciliated epithelial cells. The ultrastructural characteristics of these secretory cells during the mid to late follicular phase of the cycle suggested elevated protein synthetic activity. In addition, mRNA expression for huOGP was elevated in all regions of the oviduct in midcycle specimens. Collectively, these data indicate that huOGP is a major tissue-specific, stage-specific secretory product of the human oviduct during the periovulatory stage of the cycle and support the hypothesis that huOGP synthesis and secretion may be regulated by fluctuations in the levels of estrogen and progesterone.

Isolation, culture, and characterization of equine oviduct epithelial cells in vitro

Oviduct epithelial cells (OEC) increasingly are used to support embryonic development and to study gamete interactions with the female reproductive tract in vitro. This series of experiments was designed to characterize monolayers derived from oviduct epithelium. Epithelial cells harvested from the isthmus and ampulla of the oviducts of five estrous mares were cultured with or without the basal lamina extract, Matrigel. Within each group OEC were cultured in the presence of either estradiol-17 beta or a carrier control. All groups were subcultured three times. Epithelial cell morphology and function were examined by microscopy, analysis of secreted proteins, and immunocytochemistry. Epithelial cells attached more rapidly and reached confluence sooner when cultured on Matrigel than in uncoated wells. Cells showed variable evidence of ciliary activity up to 12 days in primary culture. Cells grown on Matrigel had a more polarized appearance in primary culture than those in uncoated wells, although no morphologic difference between anatomic site of origin or between steroid treated groups was noted. Anatomic site of origin had no effect, and steroid treatment had minimal effects, on patterns of secreted proteins. However, some differences were noted in protein secretion between cells grown with or without Matrigel. These data suggest that culture substrate may affect structure and function of OEC monolayers.

Oviductins possess chitinase- and mucin-like domains: a lead in the search for the biological function of these oviduct-specific ZP-associating glycoproteins

Over the last 10 years considerable progress has been made in the immunological and biochemical characterization of oviduct-specific glycoproteins. It is now well established that a subclass of these secretory products, designated as oviductins, associate with the zona pellucida of the ovulated oocyte and with the early embryo. Recent reports on the cloning of cDNAs of oviductins from various species, including that of golden hamster (Mesocricetus auratus) oviductin by our laboratory, allowed us to compare their deduced amino acid sequences with those of other proteins. Optimal alignment analysis showed that oviductins contain regions of significant similarity with catalytically inactive mammalian members of the bacterial and microfilarial chitinase protein family. Most importantly, a close examination of the hamster and human deduced amino acid sequences revealed that both glycoproteins possess contiguous Ser/Thr rich repeated units, clustered in their carboxy-terminal portions. These mucin-type motifs are similar in the hamster and human glycoprotein, although hamster oviductin contains more of these complete units. This striking feature might indicate that these molecules play a similar role to mucin-type glycoproteins, e.g., in protecting the oocyte and early embryo against attacks from their environment. We propose a model whereby oviductins are targeted to the oocyte via the interaction of their chitinase-like domains with specific oligosaccharide moieties of the zona pellucida. Once localized to this structure, oviductin molecules would act as a protective shield around the oocyte and early embryo by virtue of their densely glycosylated mucin-type domains.

Stage-specific immunolabeling for oviductin in the secretory granules of the oviductal epithelium of the golden hamster during the estrous cycle

BACKGROUND

We have previously localized an antigen of oviductal origin in the zona pellucida of postovulatory hamster ova. This antigen is a high molecular weight glycoprotein secreted by the non-ciliated secretory cells of the oviduct and is later transferred to the zona pellucida of the oocyte during oviductal transit. This glycoprotein is rich in N-acetyl-D-galactosamine residues and has been designated Hamster Oviductin-1. In the present study, a monoclonal antibody (MAb) raised against this oviductin was used to detect the presence of this antigen in oviductal tissue during the estrous cycle.

METHODS

Twenty mature female golden hamsters were used and were divided into five groups of five animals each according to the five different stages of the estrous cycle. Quantitative immunocytochemistry was performed on MAb-labeled thin sections of Lowicryl-embedded ampullary region of hamster oviducts. Control experiments were also carried out to assess the specificity of the immunolabeling.

RESULTS

Quantitative analysis of the immunogold labeling indicated that maximum labeling for oviductin in the secretory granules of oviductal epithelial secretory cells was found around the time of ovulation, i.e., at estrus. The intensity of immunolabeling decreased from metestrus to diestrus 1, was at a minimum at diestrus 2, and started to increase at proestrus.

CONCLUSION

Together, these quantitative results indicate that expression of oviductin in the secretory granules of the hamster oviductal secretory cells is stage specific. Maximum labeling for the antigen coincides with the time of ovulation suggesting an important role for the oviductal epithelium in contributing its secretory product to the zona pellucida of oocytes freshly released from the ovary. Since the oviduct is the site of sperm-egg interaction and where fertilization and early embryo development take place, the maximal production of oviductin at the time of ovulation may facilitate some of these crucial steps during the intricate process of reproduction.

Affinity binding of hamster oviductin to spermatozoa and its influence on in vitro fertilization

The aim of this study was to determine the influence of hamster oviductal glycoprotein (oviductin) on in vitro gamete interaction. Oviductin was purified from the oviducts using lithium 3,5-diiodosalicylate, followed by phenol extraction. Immunocytochemistry using indirect fluorescence staining revealed that oviductin binds to the sperm anterior acrosomal region. The specific binding of oviductin resulted in inhibition of in vitro fertilization in studies using cumulus-free oocytes. The inhibitory effect was dependent on the concentration of oviductin and occurred in both ovarian and oviductal oocytes but not zona-free oocytes, indicating that sperm-zona interaction was interferred by oviduction. However, the inhibitory effect of oviductin in sperm-zona interaction was reduced when cumulus-enclosed oocytes from ovaries and oviducts were used, indicating that the egg investment including cumulus oophorus has some effect on oviductin-sperm complex and maintaining the fertilizing ability.

In vitro incubation of golden (Syrian) hamster ovarian oocytes and human sperm with a human oviduct specific glycoprotein

The objective of this study was to determine if human oviduct specific glycoprotein (huOGP) would associate with hamster ovarian oocytes and human sperm during in vitro incubation. The huOGP used in these studies was partially purified from human hydrosalpinx fluid. Hamster ovarian oocytes and human sperm samples were incubated in culture medium with and without huOGP. Association of huOGP was assessed by indirect immunofluorescence assay using a polyclonal antibody prepared against huOGP. Intense fluorescence of the zona pellucida, and bright but uneven fluorescence of the perivitelline space, were observed in hamster ovarian oocytes following incubation in the presence of huOGP. A similar but more uniform pattern of fluorescence was observed when hamster oviductal oocytes (positive controls) were incubated in culture medium alone. Fluorescence was absent when oocytes were assayed with preimmune serum. The association of huOGP with the zona pellucida and perivitelline space appeared to be specific since thyroglobulin, a large molecular weight glycoprotein, and human serum albumin, the major protein in oviduct fluid, did not associate with the hamster oocytes nor inhibit huOGP association when included in the culture medium. Fluorescence was absent when human sperm incubated with huOGP were assayed with antiserum to huOGP. However, human sperm fluoresced when incubated with a uterine glycoprotein, CUPED, which had previously been shown to bind to cat sperm during in vitro incubation. Sperm also fluoresced brightly when human sperm antibody was used as a positive control. Solubilization of sperm membrane proteins postincubation and analysis of these proteins by 1-D SDS-PAGE followed by immunoblotting also failed to show an association of huOGP with human sperm. Electron microscopy of sperm both pre- and postsolubilization confirmed that the sperm membranes were removed by this process. In conclusion, the association of huOGP with hamster oocytes in vitro suggests that huOGP may associate with human oocytes in vivo, whereas that may not be true for human sperm in vivo. The association of huOGP with oocytes may serve to facilitate the process of fertilization and early embryonic development within the oviduct.

Porcine oviductal cells support in vitro bovine embryo development

This study was designed to investigate the developmental competency of in vitro-matured and in vitro-fertilized bovine embryos co-cultured with a) medium alone, b) bovine oviductal cells (BOC), c) bovine conditioned medium (BCM), d) porcine oviductal cells (POC), and porcine conditioned medium (PCM). Follicular oocytes collected from cattle at local slaughterhouses were matured and fertilized in vitro. Epithelial cells were scraped from the luminal surface tissue of either bovine or porcine oviducts collected after ovulation, cultured in TALP + 10% heat-treated fetal calf serum, and the conditioned media were collected following a 3- to 5-d incubation period. After 18 to 22 h of sperm-ova co-incubation, the fertilized and/or cleaved ova were randomly assigned to 1 of 5 co-culture groups. The results revealed that the efficiency of medium alone in supporting embryo development from the 16- to 32-cell stage up to the blastocyst stage was significantly (P<0.01) lower than of embryos co-cultured with either bovine or porcine epithelial cells, or with conditioned media from such cells. Epithelial cell co-culture, regardless of cell source, was more effective (P<0.01) than culture with conditioned medium. Co-culture in medium containing or conditioned by porcine cells was more effective in supporting bovine embryo development than co-culture with bovine-derived cells or conditioned medium. These data support the concept that oviductal cells produce a soluble component which enhances embryo development to the blastocyst stage in vitro and that the effect is not species-specific.

Immunocytochemical localization of oviduct-specific glycoproteins in the oviductal epithelium from cows at follicular and luteal phases

The immunocytochemical localization of bovine oviduct-specific glycoproteins was investigated by light and electron microscopy. Using monoclonal antibodies (MAbs) specific for bovine oviductal glycoproteins, 3 regions (fimbriae, ampulla, and isthmus) of the epithelium in the bovine oviduct we studied during the follicular and luteal phases. The MAbs reacted specifically with the oviductal epithelial cells. Intense labeling was observed in the ampullar and fimbrial epithelia of cows at the follicular phase, but the reactions were weaker at the luteal phase. In the isthmus, the immunohistochemical reaction was faint during both follicular and luteal phases. At the ultrastructural level, the MAbs bound selectively to putative secretory granules of nonciliated cells in the ampulla and fimbriae, but not in the isthmus. These results suggest that there are cyclic changes and regional differences in the production of glycoproteins in the bovine oviduct.

Immunological detection of an oviductal glycoprotein in the rat

In the golden hamster, high-molecular-weight glycoproteins are secreted by the epithelial cells of the oviduct. The present study was designed to investigate the possibility that the rat oviduct produces specific glycoproteins similar to the oviductal glycoproteins (GHOGPs) of the golden hamster. Oviductal extracts and oviductal fluids obtained from ovulatory rats were analysed by immunoblotting for the presence of glycoproteins that cross-react with a monoclonal antibody (MAb) against GHOGPs. The MAb immunoreacted with a broad band of proteins with a range of molecular weights (MWs) of above 330 kD in oviductal extracts or oviductal fluid after fractionation by electrophoresis under reducing conditions, but these proteins were not present in serum and uterine flushings. An immunohistochemical study demonstrated that the MAb bound strongly to the epithelial cells of the oviduct and, to a lesser extent, to those of the large intestine. Weak reactions were also observed with some other tissues. However, similar material of high MW was not detected in extracts of tissues from the other organs, suggesting that the glycoprotein of high MW that reacted with the MAb is specific for the oviduct. Ultrastructural immunocytochemistry revealed that the MAb reacted specifically with putative secretory granules of nonciliated cells in the oviductal epithelium. These results indicate that the oviductal epithelial cells of the rat produce a specific glycoprotein that is immunologically similar to GHOGPs.

Distribution of lectin binding sites in the oviducts of cycling and hormone-treated pigs

Gamete transport, fertilization, and early embryonic development take place in different regions of the oviduct and under different hormonal conditions. The objective of this study was to use lectins to detect variation in the distribution of glycosylated molecules on the surface of the epithelia that influence these events. Oviducts were collected from gilts on day 1 (estrus) and day 16 (diestrus) of the estrous cycle, and from gilts that were bilaterally ovariectomized on day 4 of the estrous cycle, and were subsequently treated with estradiol valerate (100 micrograms/day), progesterone (200 mg/day), or corn oil vehicle for 11 days. Six biotinylated lectins, Triticum vulgaris (WGA), Arachis hypogaea (PNA), Ulex europeus (UEA-I), Dolichos biflorus (DBA), Ricinus communis (RCA-I), and Canavalia ensiformis (Con A), were used to probe tissue from the isthmus and ampulla using peroxidase-conjugated avidin as the marker. In cyclic gilts, WGA and DBA stained more strongly in the isthmus than the ampulla on both cycle days. Staining with PNA was patchy, but greater on the apical surface of isthmic epithelium on day 16 than day 1. With UEA-I, staining was more intense in the ampulla on day 16 than day 1. Staining by PNA and UEA-I was suppressed in both the ampulla and isthmus with estradiol treatment. DBA staining was suppressed in the isthmus with both estradiol and progesterone treatments. Cilia were labelled by all lectins except WGA and PNA. Thus glycosylation patterns vary in the porcine oviduct with region and hormonal state, reflecting the variety of events that may be influenced.

Production and characterization of monoclonal antibodies specific for bovine oviductal glycoproteins

Four monoclonal antibodies (MAbs) were produced in rat cells against materials obtained from the bovine oviduct. The MAbs (1H10, 2A4, 2C5, and 1B12) reacted strongly with the oviductal epithelium of cows in the follicular phase. An immunohistochemical study demonstrated that each of the MAbs bound strongly to the supranuclear cytoplasm of epithelial cells of the oviduct, but not of the stromal cells. Antigens that reacted with the MAbs were characterized by immunoblotting analysis of proteins after fractionation by SDS-PAGE under reducing conditions of oviductal flushings obtained from cows at estrus. All MAbs strongly stained a band of protein with a molecular weight (MW) of 85-97 kD. MAb 1H10 also reacted with the minor band of a 55-kD protein. Similar antigens were not detected in uterine flushings, follicular fluid, and serum. No specific immunohistochemical reactivity with the MAbs was observed with other tissues from the reproductive tract and with nonreproductive tissues. The immunohistochemical reactions were completely eliminated by pretreatment of tissues with trypsin, but not with periodic acid, results that suggest that the antigenic determinants that react with the MAbs were proteinaceous rather than carbohydrate. We have thus established clones that produce 4 MAbs that are specific for oviduct-specific glycoproteins of the cow.

In vitro synthesis of oviductal secretory proteins by estrogen-treated ovariectomized gilts

The objective of this study was to identify, characterize, and examine oviductal secretory proteins (OSP) synthesized de novo by whole oviduct (WO), ampulla (A), and isthmic (I) tissue from ovariectomized (OVX), corn oil (CO)-, estrogen (E)-, progesterone (P)-, and E + P-treated gilts. Oviducts were collected from OVX gilts after CO, E, P, or E + P treatment for 11 consecutive days and tissue was incubated with 3H-leucine (3H-leu). Rates of 3H-leu incorporation into nondialyzable macromolecules by WO explants were greater (P less than 0.01) with E- compared to CO-, P-, or E + P-treated gilts and greater (P less than 0.05) by A explants with E- compared to CO-, P-, or E + P-treated gilts. An effect of location was noted, with A having a greater (P less than 0.01) rate of incorporation than WO or I. Conditioned culture medium was analyzed by one (1D)- and two-dimensional (2D) sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and fluorography. Analyses by 1D-SDS-PAGE revealed three major E-dependent bands (335,000, 100,000, and 80,000 M(r)) in WO and A, and one (335,000 M(r)) in the I. A 20,000 M(r) band found in A was inhibited by E, while a 60,000 M(r) band found in the A was induced by P. Analyses by 2D-SDS-PAGE resolved major E-dependent bands 2 (100,000 M(r)) and 3 (80,000 M(r)) into basic and acidic 100,000 M(r) proteins and a 75,000-85,000 M(r) protein (pI less than 4), respectively, found in WO and A, but not in I. A basic 20,000 M(r) protein and an acidic 45,000 M(r) complex, both found in A, were inhibited by E. Gel filtration of culture medium revealed a high M(r) fraction (greater than 2 x 10(6)) that was induced by E and was 6.8-fold greater in medium from A than from I. This study clearly demonstrates that 1) WO and A tissue from E-treated gilts de novo synthesize and secrete three major proteins (basic 100,000, acidic 100,000, and 75,000-85,000 M(r)); 2) these E-dependent proteins are not found in I or with other treatment; 3) several protein complexes synthesized by A are inhibited by E treatment; and 4) a high M(r) fraction, produced primarily in the A, is induced or amplified by E.

Primary culture of human fallopian tube epithelial cells and co-culture of early mouse pre-embryos

We have established a monolayer culture system for human fallopian tube epithelial cells. The cells were isolated from tubes using collagenase digestion, and were cultured in Ham's F-10 supplemented with 15% fetal calf serum. The epithelial cells derived from culture were characterized using immunocytochemical staining and electron microscopy. These cells were stained with antikeratin and anti-epithelial membrane antigen, but showed no staining after treatment with antivimentin. Electron microscopy showed many microvilli on the cell surface and tight junctions or desmosomes at areas of cell-cell contact. Cell proliferation was enhanced by epidermal growth factor, but not by fibroblast growth factor, insulin, transferrin, estradiol-17 beta, or progesterone. The 2-cell ICR mouse pre-embryos were co-cultured for 4 days with tubal epithelial cells (A) (n = 98), in cell-conditioned medium (B) (n = 83), or in medium alone (C) (n = 72). During the first 24 h in culture, for groups A and B, the rates of cleavage to the 4-cell stage were 90.9% and 81.9%, respectively. Cleavage rates in these two groups were significantly higher (P = 0.0012, P less than 0.00001) than in group C (56.9%). After 72 h in culture, the rates of development to the blastocyst stage were significantly higher for groups A and B compared to group C (89.6% and 73.5% vs. 54.5%, P less than 0.00001, P = 0.0002). These results suggest that factor(s) from tubal epithelial cells may facilitate the development of mouse pre-embryos throughout the pre-implantation stages.

Growth and differentiation of the cultured secretory cells of the cow oviduct on reconstituted basement membrane

Isolated bovine oviduct epithelial cells were cultured on plastic precoated with matrigel. The epithelial cells seeded on 10 mg/ml matrigel often organized themselves into hollow tubes or spheres with microvilli directed towards the lumen. This is the first report of describing the spontaneous tube formation of oviduct epithelial cells in vitro. The epithelial cells growing on this substratum became fully differentiated with the formation of junctional complexes and the production of secretory vesicles which migrated to apical plasmalemma. Epithelial cells seeded on 2 mg/ml matrigel (dry film) formed a subconfluent monolayer in 15-20 days after seeding. The histoarchitecture of the secretory cells growing on the matrigel dry film closely resembled that of intact epithelial cells. Occasional ciliated cells containing large numbers of mitochondria were observed in cell colonies growing on 2 mg/ml matrigel but they possessed very few intact cilia. The monolayer linearly incorporated 35S-methionine into proteins up to 8 hr in presence of estradiol or progesterone. The fluorography of the newly synthesized proteins indicated that the cell extracts of estradiol-stimulated cells contained an additional protein of approximate molecular weight of 60 kd as compared to the extracts of cells incubated without steroids or incubated with progesterone.

Effects of media and the presence of bovine oviduct epithelial cells during in vitro fertilization on fertilizability and developmental capacity of bovine oocytes

The effect of the presence of bovine oviduct epithelial cells (BOEC; Experiment 1) as well as the effects of media (Tyrode fertilization medium: TFM vs synthetic oviduct fluid: SOF), fertilization containers (drops in petri dish vs 96-wells), and the number of oocytes per drop and well (5 vs 10) for in vitro fertilization (Experiment 2) on the fertilizability and in vitro development of bovine oocytes were investigated. Immature oocytes with cumulus cells were cultured in TCM199 supplemented with 10% ECS and 2.5x10(6) granulosa cells for 24 hours at 39 degrees C under 5% CO(2) in air. In vitro fertilization was performed with frozen-thawed, heparin-treated spermatozoa (100 mug/ml, 15 minutes) and with BOEC (Experiment 1). In Experiment 2, in vitro fertilization was performed with two different media (TFM and SOF) and various conditions (culture dish and different number of oocytes). Cleavage, development to the blastocyst stage were evaluated on Day 2 and Day 7 after the start of culture. Effect of the presence of BOEC on fertilizability and developmental capacity (Experiment 1) was not significantly different. In Experiment 2, alterations in media, containers and number of oocytes during in vitro fertilization had no affect. The SOF medium showed results similar to those of TFM (normal fertilization rate: 63.2 vs 64%; cleavage: 69.3 vs 73.9%; development to the blastocyst stage: 14 vs 15%; and mean number of nuclei per blastocyst: 80.5 vs 86.6). The results indicate that the presence of BOEC during in vitro fertilization did not improve fertilizability, and that SOF as well as TFM medium can be utilized as a simple fertilization medium.

Immunocytochemical localization of an oviductal zona pellucida glycoprotein in the oviductal epithelium of the golden hamster

The immunocytochemical localization of an oviductal glycoprotein associated with ovulated eggs was investigated. Using a monoclonal antibody, we studied three regions of epithelium in the golden hamster oviduct. The monoclonal antibody reacted with the oviductal epithelium throughout the fimbriae and isthmus. Intense binding was observed in the ampulla and isthmus, especially in the caudal isthmus. In addition, reactive materials were present in the ovarian bursal sac and lumen of the ampulla. At the ultrastructural level, the monoclonal antibody reacted specifically with putative secretory granules and Golgi apparatus of nonciliated cells in the oviductal epithelium. Other cellular organelles did not react. Quantitative data indicated that the immunolabelings were intense in the ampullar and isthmic cells but weak in the fimbrial cells. Lipid droplet-like granules of the fimbriae and lysosome-like vesicles of the isthmus did not react with the monoclonal antibody. In all cases, ciliated cells did not react with the monoclonal antibody. These results suggest that the glycoprotein is primarily produced and secreted by ampullar and isthmic secretory cells and is then accumulated in the ovarian bursal sac. These findings may provide insight into regional and cellular differences in secretion of the golden hamster oviduct.

Study of the differentiation of secretory cells in the golden hamster oviductal epithelium by use of a monoclonal antibody

The ontogeny of an oviductal zona pellucida glycoprotein, designated ZP-0, in the golden hamster oviductal epithelium was investigated by means of light and electron microscopic immunolabeling studies using a monoclonal antibody. Light microscopic immunohistochemistry showed that ZP-0 appeared in the oviductal epithelium from 9.5 to 10.5 days after birth. At first, ZP-0 appeared in the Golgi region of the epithelial cells, and then increased in amount as development progressed to fill the supranuclear cytoplasm. Electron microscopic observations showed that rough endoplasmic reticulum and Golgi apparatus were well developed in non-ciliated cells of the ampullar and isthmic segments at 10.5 days after birth. Secretory granules appeared near the Golgi apparatus and markedly increased in number until 15.5 days after birth. Ultrastructural immunocytochemistry showed that ZP-0 appeared in the well-developed Golgi apparatus and then was stored within the secretory granules of developing secretory cells. ZP-0 was never present in the ciliated cells. These results indicate a coincidence between the beginning of ZP-0 biosynthesis and the morphological cytodifferentiation of secretory cells in the golden hamster oviduct during postnatal development. This leads us to the conclusion that ZP-0 is a possible differentiation marker of the golden hamster oviductal secretory cell.

Oviductal epithelium of the baboon: hormonal control and the immuno-gold localization of oviduct-specific glycoproteins

Oviducts were obtained from a series of cycling and ovariectomized steroid-treated baboons. The lining epithelium of the ampulla and isthmus was analyzed by light and electron microscopy. Both morphological and cytomorphometric analyses revealed that the morphological and functional state of the oviductal epithelium in the baboon is controlled by the ovarian steroids. Additionally, a clear cephalocaudal steroid-responsive gradient was observed when the data from the ampulla and isthmus of the same animal were compared. Within the ampulla, estradiol induced hypertrophy, hyperplasia, ciliogenesis, and secretory activity, whereas adding progesterone to the treatment regimen (+/- estradiol) resulted in atrophy, deciliation, apoptosis, and loss of the secretory activity. These cyclic processes were less evident in the isthmus. We also used an indirect electron microscopic immunogold technique and a previously characterized polyclonal antibody to determine the localization of oviduct-specific glycoproteins. These glycoproteins were present in every secretory granule observed, regardless of oviduct region, electron density, or size of the secretory granule. In summary, our data show that 1) estradiol induces and maintains the mature epithelium of the baboon oviduct, 2) steroid withdrawal or the administration of progesterone causes regression of the epithelium, and 3) the previously identified estradiol-dependent oviduct-specific glycoproteins are synthesized within and released from the secretory epithelial cells.

De novo synthesis and release of polypeptides from cyclic and early pregnant porcine oviductal tissue in explant culture

The objective of the present study was to identify and characterize in a limited manner the major de novo oviductal secretory proteins (OSP) synthesized and released by the porcine oviduct. Oviductal tissue was collected on various days of the estrous cycle (EC) and early pregnancy (EP) and cultured in a modified minimal essential medium supplemented with 100 muCi L-[3H]-leucine. Oviductal secretory activity, as measured by the rate of incorporation of 3H-leucine (dpm/mg wet tissue weight) into nondialyzable macromolecules, was greatest (P less than .01) between days 0 and 2 and reached its lowest levels on days 10 to 15. There was no difference between left and right side or pregnancy status. This increased rate of incorporation at proestrus and estrus is temporally associated with elevated levels of estrogen. Incorporation rate for ampulla was greater than for the isthmus. Analysis of oviductal culture medium by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis and fluorography revealed three protein bands of relative molecular weight (Mr) 335,000, 115,000, and 85,000, which were associated with proestrus, estrus, and metestrus and were not detectable on other days. All three proteins also incorporated 3H-glucosamine. The 115,000 Mr band was the major 3H-glucosamine-labeled protein. Two protein bands (Mr 60,000 and 20,000) were expressed with increasing progesterone during diestrus. Other de novo synthesized protein bands appear to be present throughout the EC and EP with little modulation by estrogen or progesterone. Thus, this study demonstrates that for the porcine oviduct, the increase in the incorporation rate of 3H-leucine into OSP by both whole oviduct and ampulla and de novo synthesis and secretion of three glycoproteins, Mr 335,000, 115,000, and 85,000, were associated with proestrus and estrus when events such as fertilization and early cleavage stages of embryo development occurred.

Synthesis and secretion of proteins by postpartum human oviductal tissue in culture

An explant culture system that used labelled leucine and two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) with fluorography was used to identify specific de novo synthesized and released polypeptides by the human postpartum oviduct. Both ampulla and isthmus tissue in culture exhibited de novo synthesis and release of a large number of polypeptide subunits. Immunoglobulins A and G appear to be the major proteins produced in the ampulla. In addition, two complexes of acidic (pI less than 5) polypeptide subunits are found primarily in ampulla culture medium. Two families of proteins (Mr 51,000 and 60,000) are released by the isthmus but appear to be minor in the ampulla cultures.

Secretion of proteins by cultured bovine oviducts collected from estrus through early diestrus

To characterize in vitro protein secretion by the oviduct throughout early stages of the estrous cycle, 16 cows received a luteolytic dose of PGF2 alpha and were randomly assigned to be killed on day (D) 0, 2, 5, or 8 after subsequent estrus. Explant cultures of oviducts (ampulla and isthmus) were incubated for 24 h at 39 degrees C in a modified Eagle's minimal essential medium supplemented with 50 microCi L-[4,5-3H]leucine. Oviductal secretion of de novo synthesized protein measured by incorporation of [3H]leucine into nondialyzable radioactivity in culture supernatants was greatest at D 0 and declined thereafter. Incorporation of [3H]leucine into TCA-precipitable macromolecules in tissue homogenates was also greatest at D 0. Analysis of culture supernatants by one-dimensional polyacrylamide gel electrophoresis revealed four major bands of radiolabeled proteins at greater than 97 kDa, 85-97 kDa, 55 kDa, and 30 kDa. Analysis of individual polypeptides resolved by two-dimensional polyacrylamide gel electrophoresis indicated that five of 32 individual polypeptides examined were secreted at significantly greater rates at estrus than at other times examined. One of these five polypeptides, a 97-kDa peptide with an apparent pI of 5.0, was the major secretory product at estrus and accounted for 18% of total radioactivity recovered from two-dimensional gels. Two of 32 polypeptides examined were secreted at significantly greater rates by explants of the oviduct contralateral to the side of ovulation. In summary, estrus is associated with an elevation in total protein secretion by the bovine oviduct. This increase is due to selective amplification of secretion of several but not all secretory proteins.