Apoptotic and proliferative changes during induced atresia of pre-ovulatory follicles in the rat

Transcriptional activity and splicing factors are preserved during physiological apoptosis

Apoptosis is the best-known programmed cell death that maintains tissue homeostasis in eukaryotic cells. The morphological characteristics include nuclear and cytoplasmic contraction and cytoplasmic blebbing, its biochemical hallmarks include caspase protease activity and DNA fragmentation. In rat ovaries, cell death is a normal process that occurs throughout the organism's life. Granulosa cells, the more abundant cell type forming the ovarian follicles, are eliminated via different routes of cell death. Most granulosa cells are eliminated through apoptotic cell death. In this work, we analyzed the behavior of nuclear components throughout the apoptotic process and determined how they are regionalized and conserved during follicular atresia in rat ovaries. Apoptosis was detected based on caspase-3 activity and DNA fragmentation using the TUNEL technique. We identified the transcription markers H3ac and RNA Pol II, and splicing factor SC35 by immunodetection. The nucleolar components were analyzed via light microscopy and transmission electron microscopy through immunodetection of the proteins nucleolin and nucleophosmin-1. The nuclear ultrastructure was analyzed using standard contrast and preferential ribonucleoprotein contrast. Our results demonstrate that during the progression of apoptosis, chromatin is remodeled to constitute apoptotic bodies; transcription and spliceosome elements are reorganized along with the nucleolar components. Additionally, the splicing and transcription factors are segregated into specific territories inside the apoptotic bodies, suggesting that transcriptional elements are reorganized during the apoptotic process. Our results indicate that apoptotic bodies not only are compacted, and chromatin degraded but all the nuclear components are progressively reorganized during cell elimination; moreover, the transcriptional components are preserved.

Potential long-term developmental toxicity of in utero and lactational exposure to Triclocarban (TCC) in hampering ovarian folliculogenesis in rat offspring

Triclocarban (TCC), an antimicrobial compound commonly added to a wide range of household and personal hygiene care products, is one of the most prevalent endocrine-disrupting substances (EDS). This study was conducted to elucidate whether in utero and lactational exposure to TCC could adversely affect folliculogenesis and the onset of puberty in female rat offspring. Twenty pregnant Sprague Dawley rats were equally divided into Control and TCC dam groups (supplemented daily with drinking water enriched with 0.5 mg/L of TCC) from gestational day5 to postnatal day21 (PND21). Female offspring, 20 from control and 20 from TCC dams, were subdivided into 4 subgroups (PND21, PND28, PND35 & PND42). The day of vaginal opening and first estrous cycle were determined. Ovarian sections of the offspring were processed for H&E staining and for immunohistochemical expression of Ki67, Caspase-3 and androgen receptors (AR) on the granulosa cells of ovarian follicles. Follicular count and atretic index were assessed besides, serum estradiol, progesterone, FSH and LH, C-reactive protein (CRP), malondialdehyde (MDA) and total antioxidant capacity (TAC) were measured. TCC offspring exhibited a significant delay in the onset of puberty and impedance of normal transition of the primordial follicles to more developed ones with altered cyctoarchitecture. Also, TCC decreased follicular count, proliferation and gonado-somatic index while it increased atretic index, apoptosis and AR of the granulosa cells along with disturbance of the feminine hormonal profile and oxidant/antioxidant balance. This study highlighted the potential long-term consequences of in utero and lactational exposure to TCC on the postnatal development of the ovary in rat offspring.

The effects of CLP-induced sepsis on proliferation and apoptosis of granulosa and theca cells in rat ovary: A histochemical and ultrastructural study

Sepsis is defined as a systemic inflammatory response to infection. This study is aimed to evaluate the effects of experimental sepsis on the proliferation and apoptosis of granulosa and theca cells in the rat ovary. 28-day-old immature Wistar-Albino female rats were treated with pregnant mare serum gonadotrophin to develop the first generation of preovulatory follicles. Sepsis was induced by cecal ligation and puncture (CLP). Following in vivo 5-Bromo-2-deoxyuridine (BrdU) labeling, animals were sacrificed and ovaries were embedded in paraffin and Epon. Besides electron microscopic evaluation, BrdU, cleaved caspase-3, p27 immunostaining, and TUNEL labeling were performed. In CLP-operated animals, cleaved caspase-3 immunoreactivity was significantly increased in Graafian follicles. TUNEL and BrdU labeling in the ovarian follicles were not statistically different between CLP and sham-operated rats. In septic animals, p27 immunoreactivity was increased significantly in the nuclei of oocytes and decreased in the cytoplasm of granulosa and theca cells in multilaminar primary follicles compared to the sham group. In ultrastructural evaluation, increased apoptosis was observed in theca interna and granulosa cells in both the early and late stages of follicles in the CLP group. In conclusion, experimentally-induced sepsis leads to apoptosis in ovarian follicles at advanced stages of development. Our data suggest that although sepsis may not cause a potential threat to developing follicles at least in the short term, more severe damage may occur during advanced stages of follicle development.

The effects of magnesium sulfate on cyclophosphamide-induced ovarian damage: Folliculogenesis

Cyclophosphamide (CYP) is one of the alkylating chemotherapeutic agents and its adverse effects on folliculogenesis in the ovary are well-known due to the previous scientific research on this topic. Magnesium has various effects in organisms, including catalytic functions on the activation and inhibition of many enzymes, and regulatory functions on cell proliferation, cell cycle, and differentiation. In this study, the effects of magnesium sulfate (MgSO₄) on CYP induced ovarian damage were investigated. Immature Wistar-Albino female rats of 28-days were treated with pregnant mare serum gonadotrophin (PMSG) to develop the first generation of preovulatory follicles. Rats of the experimental groups were then treated with either CYP (100 mg/kg, i.p) and MgSO₄ (270 mg/kg loading dose; 27 mg/kg maintenance doseX12, i.p) solely or in combination. Following in-vivo 5-bromo-2-deoxyuridine (BrdU) labeling, animals were sacrificed and ovaries were embedded in paraffin and Epon. In the ovaries, added to the evaluation of general morphology and follicle count; BrdU and TUNEL-labeling, cleaved caspase-3 and p27 (cyclin-dependent kinase inhibitor) staining was also performed immunohistochemically and an ultrastructural evaluation was performed by transmission electron microscopy (TEM). The number of primordial follicles were decreased and multilaminar primary and atretic follicles were increased in CYP group. After MgSO₄ treatment, while primordial follicle pool were elevated, the number of atretic follicles were decreased. Additionally, decreased BrdU-labeling, increased cleaved caspase 3 immunoreactivity and increased TUNEL labeling were observed in CYP group. In CYP treated animals, observations showed that while MgSO₄ administration caused no alterations in BrdU proliferation index and caspase-3 immunoreactivity, it significantly reduced the TUNEL labeling. It was also observed that, while p27 immunoreactivity significantly increased in the nuclei of granulosa and theca cells in the CYP group; MgSO₄ treatment significantly reduced these immunoreactivities. The ultrastructural observations showed frequent apoptotic profiles in granulosa and theca cells in both early and advanced stages of follicles in the CYP group and the MgSO₄ treatment before the CYP application led to ultrastructural alleviation of the apoptotic process. In conclusion, our data suggest that MgSO₄ may provide an option of pharmacologic treatment for fertility preservation owing to the beneficial effects of on chemotherapy-induced accelerated follicular apoptotic process, and the protection of the primordial follicle pool.

Menoprogen, a TCM Herbal Formula for Menopause, Increases Endogenous E2 in an Aged Rat Model of Menopause by Reducing Ovarian Granulosa Cell Apoptosis

The effect of Menoprogen (MPG) on ovarian granulosa cell (GC) apoptosis was investigated in vitro and in vivo in an aged rat model of menopause. Intragastric administration of Menoprogen or estradiol valerate to 14-month-old senile female rats for eight weeks increased plasma E₂ levels, as well as the weight of both ovarian and uterine tissues. Flow cytometric (FCM) analysis of isolated GCs from MPG-treated aged rats showed reductions in the G₀/G₁ ratio and apoptotic peaks. Isolated GCs also exhibited an increase in cell size and the number of cytoplastic organelles and intracellular gap junctions, the reappearance of secretory granules, and a lack of apoptotic bodies as determined by TEM. Results from a TdT-mediated dUTP nick end-labeling (TUNEL) assay revealed a reduction in TUNEL-positive GCs after MPG treatment. Immunohistochemical analysis showed a downregulation of proapoptotic Bax proteins and an upregulation of antiapoptotic Bcl-2 proteins. The addition of MPG-medicated serum to the media of cultured GCs also reduced cadmium chloride-induced apoptosis and downregulated caspase-3 protein expression. This work demonstrates that Menoprogen inhibits GC apoptosis in aged female rats and thereby increases E₂ production. This represents a novel mechanism of action for this herbal medicine in the treatment of menopausal symptoms.

Nonproliferative and proliferative lesions of the rat and mouse female reproductive system

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the female reproductive tract of laboratory rats and mice, with color photomicrographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. There is also a section on normal cyclical changes observed in the ovary, uterus, cervix and vagina to compare normal physiological changes with pathological lesions. A widely accepted and utilized international harmonization of nomenclature for female reproductive tract lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Oocyte-secreted growth differentiation factor 9 inhibits BCL-2-interacting mediator of cell death-extra long expression in porcine cumulus cell

Oocyte-secreted factors (OSFs) maintain the low incidence of cumulus cell apoptosis. In this report, we described that the presence of oocytes suppressed the expression of proapoptotic protein BCL-2-interacting mediator of cell death-extra long (BIMEL) in porcine cumulus cells. Atretic (terminal deoxynucleotidyl transferase dUTP nick end labeling-positive) cumulus cells strongly expressed BIMEL protein. The healthy cumulus- oocyte complex exhibited a low BIMEL expression in cumulus cell while the removal of oocyte led to an about 2.5-fold (P < 0.5) increased expression in oocytectomized complex (OOX). Coculturing OOXs with denuded oocytes decreased BIMEL expression to the normal level. The similar expression pattern could also be achieved in OOXs treated with exogenous recombinant mouse growth differentiation factor 9 (GDF9), a well-characterized OSF. This inhibitory action of GDF9 was prevented by the addition of a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Luciferase assay further demonstrated that BIM gene expression was forkhead box O3a (FOXO3a)-dependent because mutation of FOXO3a-binding site on the BIM promoter inhibited luciferase activities. Moreover, the activity of BIM promoter encompassing the FOXO3a-binding site could be regulated by GDF9. Additionally, we found that GDF9 elevated the levels of phosphorylated AKT and FOXO3a, and this process was independent of the SMAD signal pathway. Taken together, we concluded that OSFs, particularly GDF9, maintained the low level of BIMEL expression in cumulus cell through activation of the PI3K/FOXO3a pathway.

Histologic Features of Prepubertal and Pubertal Reproductive Development in Female Sprague-Dawley Rats

In response to growing concerns that environmental chemicals may have adverse effects on human health by altering the endocrine system, the Endocrine Disruptor Screening Program (EDSP), under the auspices of the United States Environmental Protection Agency (U.S. EPA), recently instituted a Tier I battery of tests including a female pubertal assay. This assay requires dosing of female rats from postnatal day (PND) 22 through PND 42 (or 43), the period of pubertal development in the rat, to identify test articles that may have estrogenic or antiestrogenic effects, or may alter hormones or neurotransmitters. While certain landmarks in female rat reproductive development are published, little is published on the microscopic appearance of the female reproductive tract during prepubertal and pubertal development. In this study, reproductive tissues from three female Sprague-Dawley rats were collected each day from PND 20 through PND 50, such that tissues from a total of 93 rats were collected throughout the prepubertal and pubertal period. Tissues were formalin-fixed, trimmed, paraffin-embedded, sectioned at 5-µm thickness, and examined microscopically. The major histologic features of the female reproductive tract throughout this critical period were described in detail. This information will help pathologists interpret findings observed in female pubertal assays.

How do chemotherapeutic agents damage the ovary?

BACKGROUND

Chemotherapy treatment in premenopausal women is associated with an increased risk of premature ovarian failure (POF) but the exact mechanism through which this occurs is uncertain. In this review we examine the current evidence for the direct action of chemotherapeutic agents on the ovary and discuss possible molecular pathways through which follicle loss may occur.

METHODS

A systemic search of the databases, PubMed and Google Scholar, was made for all English language articles through to 2011 in each subject area discussed.

RESULTS

POF results from the loss of primordial follicles but this is not necessarily a direct effect of the chemotherapeutic agents. Instead, the disappearance of primordial follicles could be due to an increased rate of growth initiation to replace damaged developing follicles. Likewise, the loss of oocytes need not necessarily be a direct result of damage: evidence suggests that chemotherapy drugs can also induce oocyte death indirectly via damage to somatic cells. Specific molecular mechanisms and likely ovarian targets are discussed for some of the anti-cancer drugs most commonly used to treat premenopausal women. Finally, we consider current and prospective methods of preserving fertility.

CONCLUSIONS

It is likely that different chemotherapeutic drugs act through a range of mechanisms and on different target cells. More research into the cellular mechanisms underpinning chemotherapy-induced follicle loss could lead to the generation of treatments specifically designed to prevent POF.

The involvement of neurofilament heavy chain phosphorylation in the maturation and degeneration of rat oocytes

Neurofilaments (NF) are intermediate filament proteins that were originally found to be expressed in neurons and are involved in the maintenance of axonal structure. However, there has not been much research on the expression and physiological significance of NF in other organs. In the present study, we examined the expression of NF in rat ovaries and found that NF heavy chain (NF-H) was expressed in oocytes of follicles from the primary to mature stages, ovulated oocytes, fertilized zygotes, and degenerative oocytes of atretic follicles. Cytoplasmic NF-H disappeared at the two-cell stage of embryonic development, whereas degenerative oocytes of atretic follicles continued to express NF-H even after fragmentation. An antibody that specifically recognizes phosphorylated NF-H (pNF-H) was used to examine the pattern of NF-H phosphorylation in oocytes. pNF-H was detected in the cytoplasm and nuclei of oocytes of mature and atretic follicles, ovulated oocytes, and one-cell zygotes. Treatment with 3,3'-iminodipropionitrile, which induces aberrant phosphorylation of NF in the perikarya of neurons and causes neuropathy, induced oocyte degeneration with follicular atresia, phosphorylation of NF-H in oocytes, and ovarian gene expression of cyclin-dependent kinase 5, a candidate kinase of NF-H. However, an indicator of neuron degeneration, Fluoro-Jade C, failed to stain the pNF-H-immunopositive oocytes. Our results indicate that NF-H expressed in oocytes may be involved in the maintenance of oocyte structure during follicular growth and that the phosphorylation of NF-H in ephemeral oocytes may contribute to the degeneration process of oocytes.

High doses of medroxyprogesterone as the cause of disappearance of adherence of the zona pellucida to an oocyte

The zona pellucida (ZP) is an external glycoprotein membrane of oocytes of mammals and embryos in the early stage of their development. ZP first appears in growing ovarian follicles as an extracellular substance between the oocyte and granular cells. The zona pellucid markedly affects the development and maturation of the oocyte. The morphology of the ZP-oocyte complex allows a more precise determination of the oocyte maturity. According to numerous experimental studies, ZP is essential for preimplantation embryonic development of humans and other mammals. It prevents dispersion of blastomeres and enhances their mutual interactions. ZP is a dynamic structure responsible for the provision of nutrients to early forms of oocytes in mammals. The aim of the present study was untrastructural evaluation of the ZP-oocyte contact during inhibited ovulation. Female white rats (Wistar strain) received a suspension of medroxyprogesterone acetate (MPA) in incremental intramuscular bolus doses of 3.7 mg (therapeutic dose), 7.4 mg and 11.1 mg. The animals were decapitated 5 days after the administration of MPA. Ovarian sections were evaluated under a transmission electron microscope (TEM) Zeiss EM 900. Morphometric analysis of ZP was conducted using the cell imaging system by Olympus. In females exposed to therapeutic doses of MPA, ZP showed the structure of granular-fibrous reticulum of a medium electron density with single cytoplasmic processes originating from the surrounding structures. The oocyte cell membrane generated single, delicate processes directed toward ZP. Microvilli of the oocyte were short and thin. In the group receiving 7.4 mg of MPA, ZP had the structure of a delicate, loose granular-fibrous reticulum, and the oocyte cell membrane generated single microvilli directed toward ZP. In both those groups, the close ZP-oocyte contact was observed. Otherwise, in the group exposed to the highest MPA doses (11.1 mg), thicker and more numerous oocyte microvilli were found, which did not penetrate ZP matrix. They were dense, irregularly separated contour, forming a barrier between ZP and oocyte. The present findings are likely to suggest that MPA has inhibiting effects on the synthesis of binding proteins and causes the loss of the oocyte contact with ZP.

Long-term effects of GnRH agonist, GnRH antagonist, and estrogen plus progesterone treatment on apoptosis related genes in rat ovary

OBJECTIVE

To define the long-term effects of GnRH antagonist, GnRH agonist, and estrogen plus progesterone treatments on apoptosis and apoptosis-related gene expressions, including bcl2, bax, and cyt c in rat ovary.

DESIGN

Prospective placebo-controlled experimental study.

SETTING

Obstetrics and Gynecology and Medical Biology and Genetics university departments.

ANIMAL(S)

Forty female wistar rats that were 3 to 4 months of age.

INTERVENTION(S)

Forty rats were randomly divided into 4 groups of 10 each. In group 1 (control) each rat received normal saline as placebo by gastric lavage. In group 2 (GnRH agonist) 1 mg/kg leuprolide acetate in depot form was given for 30 days. In group 3 (GnRH antagonist) each animal received 0.1 mg/kg cetrorelix every 2 days. In group 4 (estrogen plus progesterone) 0.5 mg/kg estradiol valerate and norethisterone enantate in depot form was given every 30 days. After 60 days, the animals were killed.

MAIN OUTCOME MEASURE(S)

Assessment of morphology, histology of ovaries, determination of the number of apoptotic cells, and analysis of apoptosis-related gene expression of bcl2, bax, and cyt c in the rat ovaries.

RESULT(S)

Long-term GnRH antagonist treatment significantly increased bax gene expression, but the ratio of bcl2:bax gene expression was constant compared with control group. The GnRH agonist treatment significantly increased cyt c gene expression, and estrogen plus progesterone treatment significantly decreased bcl 2 and significantly increased cyt c expressions. In the estrogen plus progesterone group, ovaries were cystic and larger than in the other groups. There was no significant morphologic change between the other groups.

CONCLUSION(S)

Long-term administration of GnRH agonist, GnRH antagonist, and estrogen plus progesterone can modulate the apoptosis-related genes in rat ovary. Although GnRH antagonist treatment does not influence apoptosis, GnRH antagonist and estrogen plus progesterone treatments seem to influence apoptosis in rat the ovary. Further clinical studies focusing on the effect of these agents on apoptosis-related genes could be performed.

Expression of anti-Mullerian hormone protein during early follicular development in the primate ovary in vivo is influenced by suppression of gonadotropin secretion and inhibition of vascular endothelial growth factor

Anti-Mullerian hormone (AMH) plays a role during early follicular development and selection. The aim of this study was to determine the pattern of AMH protein expression in the marmoset ovary and to investigate the effects of inhibition of gonadotropins or vascular endothelial growth factor (VEGF) activity on AMH expression in vivo. GnRH antagonist or VEGF Trap, a soluble decoy receptor, was administered on d 0 or 5 of the follicular phase of the cycle, and ovaries were collected at the end of the follicular phase (d 10). AMH protein was expressed in the marmoset ovary in granulosa cells from the primary stage, with the most abundant staining at the preantral and early antral stages. Inhibition of gonadotropin secretion or VEGF activity between d 0-10 of the cycle decreased AMH expression in early preantral follicles (P < 0.01), and AMH expression was decreased in late preantral follicles in the presence of the VEGF Trap (P < 0.01), compared with controls. There was significantly less AMH expression in early antral follicles with both treatments (P < 0.01), and a decrease in the ratio of oocyte-associated/basement-membrane-associated granulosa cell expression of AMH (P < 0.05). When treatments were administered from d 5-10 of the cycle, both VEGF Trap and GnRH antagonist decreased AMH expression in preantral follicles (P < 0.01) but had no significant effect on early antral follicles. In conclusion, VEGF and gonadotropins are involved in the regulation of expression of AMH in the marmoset. This AMH expression may be a marker of abnormal folliculogenesis in the absence of gonadotropin stimulation or functional angiogenesis.

Effects of gonadotropin-releasing hormone agonist/recombinant follicle-stimulating hormone versus gonadotropin-releasing hormone antagonist/recombinant follicle-stimulating hormone on follicular fluid levels of adhesion molecules during in vitro fertilization

OBJECTIVE

To compare the effects of GnRH-agonist/recombinant rFSH versus GnRH-antagonist/recombinant FSH stimulation on follicular fluid levels of soluble intercellular adhesion molecule (sICAM)-1 and vascular cell adhesion molecule-1 (sVCAM-1) during in vitro fertilization (IVF).

DESIGN

Prospective, randomized study.

SETTING

University hospital.

PATIENT(S)

Seventy-three women underwent IVF.

INTERVENTION(S)

GnRH-agonist/rFSH or GnRH-antagonist/rFSH administration and collection of follicular fluid from 3 small (11-14 mm in diameter) and 3 large (18-21 mm in diameter) follicles on the day of oocyte retrieval.

MAIN OUTCOME MEASURE(S)

Follicular fluid levels of sICAM-1 and sVCAM-1 and intrafollicular estradiol and progesterone were also measured.

RESULT(S)

Women who underwent GnRH-agonist/rFSH showed higher concentrations of sICAM-1 in both small and large follicles were compared with patients who received GnRH-antagonist/rFSH treatment; follicular fluid levels of sVCAM-1 were similar between the 2 stimulation protocols. Content of sICAM-1 in small and large follicles positively correlated with the number of follicles of > or =15 mm and the number of oocytes that were retrieved in both study groups. Concentrations of follicular fluid sVCAM-1 and progesterone were higher in large than in small follicles and were correlated positively to each other in both follicular classes.

CONCLUSION(S)

In IVF, GnRH-agonist/rFSH is associated with higher follicular fluid levels of sICAM-1 compared with GnRH-antagonist/rFSH regimen. Intrafollicular sICAM-1 content may predict ovarian response, and sVCAM-1 appears as an indicator of the degree of follicular luteinization.

Levels of apoptosis in human granulosa cells seem to be comparable after therapy with a gonadotropin-releasing hormone agonist or antagonist

OBJECTIVE

To compare levels of apoptosis in granulosa cells from women treated with the gonadotropin-releasing hormone (GnRH) agonist triptorelin or the GnRH antagonist cetrorelix.

DESIGN

Randomized, prospective study.

SETTING

University hospital.

PATIENT(S)

Thirty-two women undergoing assisted reproduction techniques after ovulation induction with recombinant follicle-stimulating hormone (FSH) plus GnRH agonist or antagonist.

INTERVENTION(S)

Granulosa cells were isolated from follicular aspirates after oocyte removal.

MAIN OUTCOME MEASURE(S)

Apoptosis was assessed with Annexin V binding assay, terminal deoxynucleotidyl transferase (TdT)-mediated nick-end labeling (TUNEL) assay, flow cytometric analysis of DNA, and ultrastructural analysis of cell morphology in transmission electron microscopy. Serum and follicular hormonal levels were also determined.

RESULT(S)

Annexin V binding and TUNEL assays revealed comparable percentages of apoptosis in the two groups under investigation. Analysis of DNA histograms revealed a similar cell cycle distribution in the two groups. Ultrastructural analysis only occasionally displayed patterns of chromatin margination in apoptotic cells. The mean concentrations of all the follicular fluid steroid hormones evaluated (E2, T, and P) were significantly lower in the GnRH antagonist-treated group.

CONCLUSION(S)

Therapy with a GnRH agonist or antagonist is associated with comparable levels of apoptosis in granulosa cells.

[Apoptosis of the follicular cells: its implication in ovarian induction protocols]

Atresia, a degenerative process through which many follicles are removed from the grown pool of follicles involves apoptotic changes in the follicular cells. This review analyses the endocrine regulation of apoptotic cell death in ovarian follicle. FSH is the major survival factor for preovulatory follicle but follicle integrity, in vitro, was necessary to its action on granulosa cell. The role of LH is more ambivalent. FSH and LH exert their activity via activation of the cAMP signal. High levels of intracellular cAMP could enhance steroidogenesis and in the same time induce apoptosis in granulosa cells. Moreover, no correlation between steroidogenesis and apoptosis can be established. During ovarian stimulation in IVF protocol, the use of LH, of coasting and of GnRH agonists and antagonists could be deleterious in follicle survival.

In utero and lactational exposure of Long-Evans rats to ammonium perchlorate (AP) disrupts ovarian follicle maturation

Ammonium perchlorate (AP) is a powerful oxidizer manufactured almost exclusively for the aerospace industry. AP salts are also used in airbags, flares, fertilizers, enamels and paints. As a result of widespread industrial use, AP has become a persistent environmental contaminant of drinking water in several U.S. states. AP ion disrupts the trapping of iodide as well as facilitates the discharge of unorganified iodide from the thyroid gland. Such disturbances in thyroid hormone concentrations during critical periods of development are then known to cause profound reproductive and developmental defects, since thyroid hormones modulate both follicular development and steroidogenesis and affect estrogen metabolism and receptor. This study was designed (1) to determine whether exposure to a low or high concentration of AP (LAP, HAP) exerts detrimental effects on follicle maturation in the Long-Evans hooded rat and (2) to determine whether the modulatory effects of AP can be ameliorated by levo-thyroxine sodium (T4) supplementation. Animals were treated via deionized drinking water on GD 7-21 with LAP (0.4 mg/kg/day) or HAP (4.0 mg/kg/day). Half of each group was also given T4 supplements via drinking water on GD 7-21. Female pups were sacrificed on postnatal days 24/25, and the ovaries were excised, fixed for histology and analyzed. The analysis included a count, measurement and classification of preantral and antral follicles in the greatest cross-sectional area of the ovary. The results indicated that treatment with the HAP significantly reduced the number of preantral follicles <50,000 microm2 and the total number of antral follicles in the <50,000, 50-100,000 and >100,000 microm2 size classes. In ovaries treated with the LAP, we observed no significant decrease in preantral follicles of any size class and only a significant reduction in the largest antral follicles. T4 only circumvented the effect on the number of small preantral and antral follicles; however, a significant diminution in the antral follicle number persisted in the mid-sized (HAP) and large (LAP, HAP)-sized classes. These data support the hypothesis that AP reduces the number of preantral and antral follicles in certain size classes in rats exposed during a critical period of development, and that T4 can attenuate the effects of AP on small preantral and antral follicles, but not on medium or large antral follicles. (T35ES007292 & ES08342.).

Morphodynamics of the follicular-luteal complex during early ovarian development and reproductive life

Female reproductive activity depends upon cyclic morphofunctional changes of the ovarian tissue during the female's fertile period, but the primum movens of an active gonadal rearrangement can be found from early phases of embryo development. To offer a basic account of the main steps of ovarian dynamics, we review the morphofunctional behavior of the follicular-luteal complex in an integrated study using light microscopy and transmission and scanning electron microscopy as well as through the use of numerous drawings. Particular emphasis is given to some reproductive aspects including (1) germ-somatic cell relationships and onset of folliculogenesis during early gonadal development; (2) follicular development and oocyte-follicle cell associations through adult folliculogenesis, finally leading to ovulation; (3) morphodynamics of corpus luteum formation, development, and regression, and (4) degenerative processes involving germ and somatic cells. The results reported, many of which originated in our laboratory, arise from some experiments on laboratory mammals but mostly from a large selection of human specimens. The data obtained are integrated and correlated with classic reports as well as with current views. Crucial biochemical, histophysiological, and clinical aspects are also emphasized.

Prevention of thecal angiogenesis, antral follicular growth, and ovulation in the primate by treatment with vascular endothelial growth factor Trap R1R2

This study was designed to investigate the effects of inhibition of thecal angiogenesis on follicular development in the marmoset monkey (Callithrix jacchus). To inhibit vascular endothelial growth factor (VEGF), a soluble combined truncated form of the fms-like tyrosine kinase (Flt) and kinase insert domain-containing receptor (KDR) receptor fused to IgG (VEGF Trap R1R2) was administered for 10 d during the follicular phase of the cycle. Changes in angiogenesis and follicular cell proliferation were quantified using immunocytochemistry for bromodeoxyuridine to obtain a proliferation index, CD31 to visualize endothelial cell area, and dual staining to distinguish thecal endothelial cell proliferation. The effects of the treatment on follicular development were assessed by morphometric analyses by measuring follicle diameter, thecal thickness, and a proliferation index for granulosa cells. Follicular atresia was detected and quantified using the terminal deoxynucleotidyltransferase-UTP nick end labeling method. Effects on gene expression of VEGF and its receptors, Flt and KDR, were studied by in situ hybridization. VEGF Trap R1R2 treatment resulted in a significant decrease in thecal proliferation and endothelial cell area, demonstrating the suppression of thecal angiogenesis. The absence of a normal thecal vasculature was associated with a significantly reduced thecal thickness. Antral follicular development was severely compromised, as indicated by decreased granulosa cell proliferation, decreased follicular diameter, and lack of development of ovulatory follicles. Furthermore, the rate of atresia was significantly increased. VEGF expression in granulosa and thecal cells increased after treatment, whereas Flt and KDR expressions in thecal endothelial cells were markedly decreased. These results show that VEGF Trap treatment is associated with the suppression of follicular angiogenesis, which results in the inhibition of antral follicular development and ovulation.