Transport of eggs from the fallopian tube to the uterus as a function of oestrogen

Immunohistochemical localization of estrogen receptor alpha (ERα) in the oviduct of Indian buffalo during follicular and luteal phases of estrous cycle

The localization and distribution of estrogen receptor alpha (ERα) in different segments of oviduct of buffalo during follicular and luteal phases of estrous cycle were investigated using immunohistochemistry. Tissue samples from the different segments of oviduct from 12 buffaloes (six each during follicular and luteal phases of estrous cycle) were collected from slaughter house after assessing the gross morphology of ovaries. In addition, blood samples were collected from the animals before slaughter to estimate levels of estrogen and progesterone hormones. The tissue distribution of estrogen receptor was determined by immunohistochemical technique using one-step polymer HRPO staining system. The estrogen receptor was localized in the lamina epithelialis, propria submucosa, tunica muscularis, and tunica serosa. The maximum localization was observed in the lamina epithelialis, where both ciliated and secretory cell types were positive for ERα. Percentage of positive cells varied during the follicular and luteal phases of estrous cycle. The lining epithelium of oviductal glands was also intensely positive for ERα. No immunostaining was observed in any tunic of the oviduct when the primary antibody was replaced by antibody diluent or buffer, and it served as negative control. The data showed that highest immune positive cells were observed in the ampulla region of the oviduct and these cells were lowest in the utero-tubal junction (p < 0.05). Infundibulum, ampulla, and isthmus showed a higher percentage of ERα-positive cells during follicular phase of estrous cycle as compared with those of the luteal phase of estrous cycle (p < 0.05). There was no significant difference in the percentage positive cells during the two phases of estrous cycle in the utero-tubal junction. Immunogold labeling with anti-ERα antibody confirmed the findings of immunohistochemical study at subcellular level. The higher expression during the follicular phase was directly correlated with the level of estrogen hormone.

Morphology and Aquaporin Immunohistochemistry of the Uterine Tube of Saanen Goats (Capra hircus): Comparison Throughout the Reproductive Cycle

The expression of six different aquaporins (AQP1, 2, 3, 4, 5 and 9), integral membrane water channels that facilitate bi-directional passive movement of water, was investigated by immunohistochemistry in the uterine tube of pre-pubertal and adult Saanen goats (Capra hircus), comparing the different phases of the oestrous cycle. Regional morphology and secretory processes were markedly different during the goat oestrous cycle. The tested AQP molecules showed different expression patterns in comparison with already studied species. AQP1-immunoreactivity was evidenced at the endothelium of blood vessels and in nerve fibres, regardless of the tubal tract and cycle period. AQP4-immunoreactivity was shown on the lateral plasmalemma in the basal third of the epithelial cells at infundibulum and ampulla level in the cycling goats, more evidently during follicular than during luteal phase. No AQP4-immunoreactivity was noticed at the level of the isthmus region, regardless of the cycle phase. AQP5-immunoreactivity, localized at the apical surface of epithelial cells, increased from pre-puberty to adulthood. Thereafter, AQP5-immunoreactivity was prominent during the follicular phase, when it strongly decorated the apical plasmalemma of all epithelial cells at ampullary level. During luteal phase, immunoreactivity was discontinuous, being weak to strong at the apex of the secretory cells protruding into the lumen. In the isthmus region, the strongest AQP5-immunoreactivity was seen during follicular phase, with a clear localization in the apical plasmalemma of all the epithelial cells and also on the lateral plasmalemma. AQP2, 3 and 9 were undetectable all along the goat uterine tube. Likely, a collaboration of different AQP molecules sustains the fluid production in the goat uterine tube. AQP1-mediated transudation from the blood capillaries, together with permeation of the epithelium by AQP4 in the basal rim of the epithelial cells and final intervening of apical AQP5, could be involved in fluid production as well as in secretory processes.

Roles of the oviduct in mammalian fertilization

The oviduct or Fallopian tube is the anatomical region where every new life begins in mammalian species. After a long journey, the spermatozoa meet the oocyte in the specific site of the oviduct named ampulla and fertilization takes place. The successful fertilization depends on several biological processes that occur in the oviduct some hours before this rendezvous and affect both gametes. Estrogen and progesterone, released from the ovary, orchestrate a series of changes by genomic and nongenomic pathways in the oviductal epithelium affecting gene expression, proteome, and secretion of its cells into the fluid bathing the oviductal lumen. In addition, new regulatory molecules are being discovered playing important roles in oviductal physiology and fertilization. The present review tries to describe these processes, building a comprehensive map of the physiology of the oviduct, to better understand the importance of this organ in reproduction. With this purpose, gamete transport, sperm and oocyte changes in the oviductal environment, and other interactions between gametes and oviduct are discussed in light of recent publications in the field.

Transport of ova transferred to rabbit oviducts at varying intervals after human chorionic gonadotropin injection

Ova obtained from donors were transfered to the oviducts of New Zealand White rabbits at various times after injection of human chorionic gonadotropin. The rabbits were killed at varying intervals after transfer. The genital tracts were removed, divided into segments (ampulla, isthmus, uterus, and vagina), and flushed to recover the ova. The experiments demonstrated the following: (1) A mechanism is present that retains some of the transferred ova above the ampullary-isthmic junction (AIJ). This mechanism is most efficient 60 hours after hCG injection. (2) Transferred ova that succeed in negotiating the AIJ are found in locations appropriate to the time elapsed from ovulation, rather than from transfer; i.e., they "catch up" to the endogenous ova.

Demonstration of postovulatory sphincter action by the isthmus of the rabbit oviduct

Doughnut-shaped, carbon-impregnated rubber microtransducers calibrated to measure changes in diameter are used to demonstrate the occurrence of a sphincter action in the isthmus of the rabbit oviduct following human chorionic gonadotropin (HCG)-induced ovulation. The postovulatory constricture of the isthmus is temporal and coincides with the period when ova are retained in the oviduct. The mean change in diameter of transducers positioned within the lumen of the isthmus in rabbits treated with HCG are significantly different from mean changes observed in nontreated control rabbits when tested at 8-hour intervals over a 104-hour period. The difference is due to a statistically significant decrease in transducer diameter which occurs between 16 and 56 hours post-HCG injection. Treatment with exogenous estrogen in combination with HCG enhances both the magnitude and duration of this constricture. Significant differences occur between 8 and 104 hours. Pretreatment with progesterone prior to HCG-induced ovulation completely blocks the constricture of the isthmus. Both oviducts exhibit identical responses following HCG-induced ovulation. Sphincter action is not confirmed to a small localized segment of the isthmus but occurs over a wide area.