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Influence of bovine ampullary and isthmic oviductal fluid on sperm-egg binding and fertilization in vitro.

The objective of this study was to determine the effects of oviductal fluid on sperm binding and fertilization in vitro when either bovine oocytes or both spermatozoa and oocytes are incubated in fluid from different regions of the oviduct and at different stages of the oestrous cycle. Oocytes, or oocytes and spermatozoa, were incubated in nonluteal and luteal oviductal fluid obtained from the whole, isthmic or ampullary oviduct of dairy cows. Gametes were washed and coincubated in fertilization medium for 18 h, and then observed for sperm binding and penetration. More spermatozoa bound to oocytes that were preincubated in nonluteal oviductal fluid than to those that were incubated in luteal oviductal fluid; however, there were no differences in fertilization rates between the two treatments. More spermatozoa bound to oocytes incubated in isthmic than in ampullary oviductal fluid. However, if both gametes were incubated in oviductal fluid before their coincubation, binding was higher when both gametes were incubated in ampullary oviductal fluid. By reducing the time of coincubation of spermatozoa with the oocytes, differences in fertilization rates were seen among the various oviductal fluid treatments. At 14 and 16 h of coincubation, more oocytes were fertilized if spermatozoa were preincubated in isthmic oviductal fluid and oocytes were preincubated in ampullary oviductal fluid than if both gametes were incubated in whole or ampullary oviductal fluid. Because both sperm binding to the zona pellucida and fertilization rates were greater in treatments in which gametes were exposed to regional oviductal fluid than when they were incubated in whole oviductal fluid, it is concluded that oviductal fluid from different regions of the bovine oviduct may play different roles in facilitating fertilization.

Animals↗

Oviduct contractile response to vaginal distension: identification of vagino-tubal reflex.

OBJECTIVE: The effect of vaginal distension on the oviduct contractile activity during penile thrusting at coitus could not be traced in the literature. We investigated the hypothesis that vaginal distension effects oviduct contraction, which assists in ovum transport along the oviduct. METHODS: Oviduct pressure was measured upon vaginal condom distension in 16 women (mean age 32.2+/-1.2 years) scheduled for abdominal hernia repair and oviduct ligation for sterilization. The test was repeated after individual anesthetization of the vagina and oviduct. RESULTS: Ten milliliters vaginal distension effected pressure elevation of the ampullary (AO) and isthmic (IO) parts of the oviduct (p<0.01, p<0.01 respectively) and a decrease in intramural oviduct (IMO; p<0.01). Twenty milliliters distension further increased the pressure in the AO and the IO (p<0.001, p<0.001) and decreased it in IMO (p<0.001). Vaginal distension with greater volumes produced an oviduct pressure response similar to that with 20 ml distension (p>0.05). Vaginal distension of anesthetized vagina or oviduct did not evoke the oviduct pressure response, but saline infusion did. CONCLUSIONS: Vaginal distension seems to produce oviduct motile activity as evidenced by oviduct pressure changes, which appear to assist in sperm-ovum transport and fertilization. These oviduct changes are suggested to occur reflexly through the "vagino-tubal reflex." Pathologic changes of the oviduct presumably interfere with this reflex action, a point that needs to be investigated.

Coitus↗

Kinetics of sperm penetration and fertilization in vitro in hamster follicular and oviductal ova.

This study compared kinetics of in vitro sperm penetration and fertilization of in vivo matured follicular vs. oviductal hamster ova. Monospermic fertilization in cumulus-intact (C+) and cumulus-free (C-) follicular ova was highest at sperm concentrations of approximately 50 and 1.0 x 10(4) sperm/ml, respectively. The cumulus layer was a barrier to sperm penetration, but penetration of C-follicular ova was still lower than with C-oviductal ova. At 1 h of sperm:egg coincubation, 21% of C- follicular ova was penetrated vs. 77% of C- oviductal ova, while by 4 h these values were 71% and 98%, respectively. In contrast, activation of zona-free follicular and oviductal ova was not different (83-99%). However, at 2 h male pronuclear formation was lower in follicular ova (9%) than in oviductal ova (26%, P < 0.05). To test the hypothesis that lower and slower penetration with follicular ova compared with oviductal ova is due to lack of oviductal exposure, effects of hamster periovulatory oviductal fluid on penetration and fertilization kinetics of C- follicular ova were examined. Adding oviductal fluid did not improve penetration of follicular ova to levels equivalent to oviductal ova, but 3 h preincubation of follicular ova with oviductal fluid improved both zona penetration and male pronucleus formation to levels equivalent to those in oviductal ova. We conclude that kinetics of sperm penetration and fertilization in follicular ova are retarded, that these deficiencies derive from lack of ovum modulation by oviductal secretions, and that prolonged oviductal exposure of ova is essential for achieving full competence.

Animals↗

Meiosis resumption of canine oocytes cultured in the isolated oviduct.

The aim of this study was to investigate the effects of culture in isolated oviducts relative to meiotic maturation, the time required to resume meiosis and the viability of the canine oocytes. For this purpose, cumulus-oocyte complexes and isthmus-ampullar tracts of the oviducts were collected from bitches undergoing ovariohysterectomies and destined to two experiments of culture. In experiment 1, the oocytes were cultured for 24 or 30 h: (1) in 100 micro l drops under oil; (2) on the mucosal epithelium of the open oviducts; (3) in the ligated oviducts. In experiment 2, oocytes were cultured in the ligated oviduct for 24, 30 and 48 h. A group of control oocytes was not cultured (0 h). The results showed that within 30 h of culture, a higher proportion of oocytes (p < 0.001) resumed meiosis in the ligated oviduct (63.8%) than in drop (20.4%) or in the open oviduct (27.1%). Moreover, 24 and 30 h of culture assured higher proportions of meiosis resumption than 48 h (69.2 and 59.1% vs 35.8%, p < 0.005). Oocyte resumption of meiosis was mainly determined by oocytes at meiotic stages preceding metaphase I, while stages between metaphase I and II in the ligated oviduct ranged between 12.5 and 31.9%. The extension of the culture time up to 48 h in the oviduct increased oocyte degeneration significantly (59.3%, p < 0.0001) compared with 24 and 30 h (18.7 and 27.3%, respectively) and the oviductal epithelium showed nuclear picnosis and degeneration following culture. The present study suggests that the close physical interaction between the canine oocytes and the oviductal tract positively affects oocyte maturation, and meiosis is resumed within 30 h of culture. Moreover, the oocyte survival is better preserved within 30 h in the ligated oviduct compared with the conventional culture in drop or to the culture in the open oviduct, but the ligated oviduct does not assure viability of the oocytes up to 48 h of culture.

Animals↗

Regional distribution and hormonal control of estrogen-dependent oviduct-specific glycoprotein messenger ribonucleic acid in the baboon (Papio anubis).

Our objective in this study was to complete the sequence of the baboon oviductal glycoprotein, examine the hormonal regulation of the oviductal glycoprotein mRNA, and determine whether there was a regional variation within the oviduct in the level of oviductal glycoprotein mRNA expression. Finally, because of the structural similarity of the amino terminal end of the oviductal glycoprotein to chitinases, we sought to determine whether the oviductal glycoprotein functions as a glycosyl hydrolase. The total transcript length of the baboon oviductal glycoprotein was determined to be 2228 nucleotides in length plus a poly(A) tail. The largest open reading frame was 623 amino acids, which would produce a protein of 69.3 kDa. The first 420 amino acids were highly homologous to the amino acid sequence of other oviductal glycoproteins, but the remainder of the sequence differed considerably from that of all other species except the human. Although the N-terminal region exhibited sequence similarity to chitinases, the oviductal glycoprotein did not exhibit any activity towards typical chitinase substrates. The oviductal glycoprotein mRNA levels were elevated to approximately the same extent in the fimbria, ampulla, and isthmus of the oviduct after estradiol treatment and in the late follicular stage of the menstrual cycle. The oviductal glycoprotein mRNA levels were lower in the early follicular stage and early luteal stage and were not detectable in the late luteal stage or in progesterone-treated baboons. These results indicate that the oviductal glycoprotein mRNA is induced by estradiol and is present at the highest levels at the time of fertilization. Although there is structural homology with chitinases, no such glycosyl hydrolase activity could be detected. However, the common structure of the N-terminal region of the oviductal glycoproteins implies that it has the same, as yet unknown, function in all species.

Amino Acid Sequence↗

Oestrogen-dependent expression of LH/hCG receptors in pig Fallopian tube and their role in relaxation of the oviduct.

The current studies investigated the concentration and distribution of LH receptors in the oviduct of ovariectomized gilts at various times after administration of oestradiol benzoate (10 micrograms kg-1 body weight) to determine whether LH participates in the regulation of oviductal contractions. Polyclonal antibodies to the LH receptor were used in immunocytochemical and western blot analyses of oviductal tissues. The mechanical activity of the isthmus and ampullar segments of oviduct, collected from 16 cyclic gilts, was recorded for 30 min after LH or hCG treatment. In the oviduct, there was little competition for receptor occupancy between hCG and pig FSH, bovine thyroid-stimulating hormone (TSH), pig growth hormone (GH) and pig prolactin (1.2, 0.1, 0.01 and < 0.001%, respectively) but pig LH could completely inhibit the binding of [125I]hCG. Oestradiol benzoate increased (P < 0.01) the number of LH binding sites in oviduct 24, 48 and 72 h (0.60 +/- 0.08, 1.62 +/- 0.15, 2.48 +/- 0.35 fmol mg-1 protein; n = 4 per treatment, respectively) after injection compared with the control gilts treated with corn oil (0.20 +/- 0.04 fmol mg-1 protein; n = 4). The affinity of oviductal LH/hCG binding sites (Ka) varied from 4.0 to 8.5 x 10(10) l mol-1 and was similar to that of luteal cell binding sites (6.1 x 10(10) l mol-1). Oestradiol benzoate also resulted in more intense LH receptor immunostaining of the tubal mucosal epithelium, smooth muscle cells and blood vessels as compared with controls. Western blotting has revealed that the pig oviduct, similar to the corpus luteum, contains 75, 48 and 45 kDa immunoreactive LH receptor proteins. Treatment with LH in vitro (100 ng ml-1) affected the contractility of oviduct. During the peri-ovulatory stage of the oestrous cycle, the amplitude, frequency and area under curve(s) of the isthmus decreased (P < 0.05), as did the frequency and area under curve (P < 0.05 and P < 0.01, respectively) of the ampulla (n = 4). The frequency and area under curve of the oviductal contractions were also significantly reduced during the early follicular phase of the oestrous cycle (P < 0.05). There was no effect of LH (or hCG) on the frequency and area under curve of the oviductal contractions during luteal stages of the oestrous cycle (n = 8). These data indicate that (1) the pig oviduct possesses immunoreactive and functional LH receptor, (2) oestradiol promotes the synthesis of LH receptor in the epithelium and smooth muscles, and (3) LH causes the relaxation of oviduct, especially during the peri-ovulatory stage of the oestrous cycle. In summary, the results of the present study indicate that LH can control oviductal contractions directly and may be partially responsible for the relaxation of isthmus during fertilization in pigs.

Analysis of Variance↗

Early developing embryos affect the gene expression patterns in the mouse oviduct.

Fertilization and development of mouse embryos occur in the ampullae of oviduct. We hypothesize that fetal-maternal communication exists in the preimplantation period, allowing optimal development of embryos. It is known that embryotrophic factors from oviduct affect the development of embryos. Although embryos affect their own transport in the oviduct, the mechanism of action is unknown. As a step toward understanding the action of embryos on oviductal physiology, we adopted suppression subtractive hybridization (SSH) to compare the gene expression in the mouse oviduct containing early embryos with that of oviduct containing oocytes. Ten to twelve 1-cell mouse embryos were transferred to one oviduct of a foster mother and similar number of oocytes were transferred to the contralateral oviduct. The animals were sacrificed after 48 h and their oviducts were excised for mRNA study. Using SSH, we screened out 250 putative positive clones from the subtracted embryo-containing oviduct library and 97 of them were screened positive by reverse dot-blot analysis. DNA sequence analysis identified genes that shared high homology with sequences in GenBank/EMBL database with unknown functions. Overall, 13 of the 90 high-quality sequences (14%) were homologous to 6 different genes previously described. Reverse Northern analysis confirmed that the expression of these genes were higher in the embryo-containing oviduct than in the oocyte-containing oviduct. About 12% of these clones (11/90) were novel. This article is the first to report identification of genes in the oviduct that are upregulated in the presence of embryos during the preimplantation period.

Animals↗

Effects of age and gonadal steroids on the localization of antigen-presenting cells, and T and B cells in the chicken oviduct.

The effects of age and gonadal steroids on the localization of immunocompetent cells, including antigen-presenting cells that contain the major histocompatibility complex (MHC) class II antigen, and T and B cells in the chicken oviduct were studied. Oviductal tissues were collected from laying and immature hens treated with diethylstilboestrol (an analogue of oestrogen) or progesterone. Cryostat sections of the tissues were immunostained for MHC class II, CD3 (T-cell antigen) and Bu-1 (immature B-cell antigen), and examined under a light microscope and an image analysis system. MHC class II+, CD3+ and Bu-1+ cells were observed in the mucosal epithelium and stromal connective tissue of both the laying and immature hens. MHC class II+ cells in the oviductal stroma appeared in association with oviductal development during sexual maturation and increased with ageing thereafter. The infiltration of CD3+ and Bu-1+ cells into the oviductal tissues increased in young laying hens compared with immature hens and decreased in old laying hens compared with young laying hens. Diethylstilboestrol increased the population of MHC class II+ and CD3+ cells in the stroma of the infundibulum and vagina, but had no significant effect on the population of Bu-1+ cells in the oviduct of immature hens. Progesterone increased the population of CD3+ cells in the stromal tissue of oviductal segments from all hens, and of Bu-1+ cells in the mucosal epithelium of the infundibulum and magnum, but had little effect on the frequency of MHC class II+ cells in the oviduct of immature hens. There were typically more immunocompetent cells in the infundibulum and vagina than in the other oviductal segments in laying hens and immature hens treated with sex steroids. These results suggest that local immunity in the chicken oviduct is enhanced during sexual maturation and possibly decreases during ageing. Gonadal steroids may play a significant role in the regulation of local immunity in the oviduct. The effects of oestrogen and progesterone on the influx of these immunocompetent cells into the oviduct differs among cell types and oviductal segments.

Aging↗

Electrophoretic characterization of equine oviductal fluid.

To characterize further the events involved in fertilization and early embryonic development in the mare, effect of the estrous cycle on oviductal fluid proteins was investigated. Five mares had indwelling cannulas placed in their oviducts so that fluid could be collected throughout the estrous cycle. Daily fluid volumes were recorded and mares were monitored for signs of standing estrus. Oviductal fluid samples were pooled across mares according to stage of cycle (either estrus or nonestrus) for further analysis. Two-dimensional polyacrylamide gel electrophoresis (PAGE) was used to determine proteins present in estrus-associated and nonestrus-associated equine oviductal fluid as compared to blood serum from the same mares. Oviductal fluid volumes increased significantly during estrus to an average of 3.94 ml/24 hr from 1.44 ml/24 hr during nonestrus. Total oviductal protein increased significantly from 24.6 mg/24 hr during nonestrus to 53.9 mg/24 hr during estrus. One-dimensional PAGE demonstrated that the proteins in equine oviductal fluid were present throughout the cycle and also common to equine serum. Reducing conditions revealed one band at 106 kDa detected only in nonestrus-associated oviductal fluid, while nonreducing conditions revealed bands at 48 and 25 kDa that were present in oviductal fluid in general. Two-dimensional PAGE demonstrated three 50 kDa proteins that were detected only in estrus-associated oviductal fluid and several 24 kDa proteins detected only in nonestrus-associated oviductal fluid. Those proteins found only in estrus-associated oviductal fluid may be vital to the fertilization process, while those found only in nonestrus-associated oviductal fluid may be vital to early embryonic development.

Animals↗

Messenger RNA encoding an estrogen-dependent oviduct secretory protein in the sheep is localized in the apical tips and basal compartments of fimbria and ampulla epithelial cells implying translation at unique cytoplasmic foci.

Data from our laboratory have shown that an estrogen (E2)-dependent M(r) 90,000-92,000 protein and its mRNA are synthesized and expressed in abundant amounts at estrus from the fimbria and ampulla, not isthmus, oviduct of the sheep. Immunocytochemical studies have shown that the M(r) 90,000-92,000 protein is contained in apical secretory granules of oviduct epithelial cells. The objective of this study was to determine whether the mRNA for the E2-dependent oviduct protein was localized and compartmentalized in similar manner. Fimbria, ampulla, and isthmus oviducts obtained from estrous ewes were flash frozen in liquid nitrogen, cryosectioned, fixed in 4% paraformaldehyde, hybridized with digoxigenin (DIG)-labeled oviduct-specific riboprobes, incubated in anti-DIG antibodies conjugated with alkaline phosphatase, and developed in color substrate. Oviduct protein-specific transcripts were localized to basal perinuclear compartments and, surprisingly, at sites distant from the nucleus in the apical cytoplasm of epithelial cells in the fimbria and ampulla. No specific reaction product was observed in the underlying mucosa or smooth muscle layers. Oviduct protein mRNA was contained predominantly in the apical cytoplasm of epithelial cells at the free margins of mucosal folds and in the basal regions of cells located at the crypts of longitudinal folds. No reaction product was present when sections of the fimbria and ampulla oviduct of estrous ewes were incubated in sense riboprobe to the oviduct protein. In addition, when sections of the isthmus oviduct obtained from estrous ewes or fimbira and ampulla oviducts from long-term ovariectomized ewes were hybridized with antisense riboprobes no specific reaction product was detected. Electron microscopy of oviduct protein mRNA containing areas revealed the presence of secretory granules, rough endoplasmic reticulum (RER) and Golgi in the apical cytoplasm, and RER in the basal regions of epithelial cells. These data show that the mRNA encoding an E2-dependent oviduct-specific protein is distributed in epithelial cells at perinuclear foci and at sites distant from the nucleus, which are also the sites of protein localization and protein synthesizing organelles, implying translation at unique cytoplasmic foci.

Animals↗

Crustacean cardioactive peptide is a modulator of oviduct contractions in Locusta migratoria.

Crustacean cardioactive peptide (CCAP) stimulates the contractions of locust oviducts. CCAP increased the basal tonus and increased the frequency and amplitude of phasic contractions, as well as the amplitude of neurally-evoked oviduct contractions in a dose-dependent manner. Oviducts from Vth instar larvae and adult locusts aged 10 days or less, were more sensitive to CCAP than oviducts from adult locusts aged 12 days or more. This may be indicative of a differential expression of number or subtypes of CCAP receptors on the oviducts at different ages, and may be related to reproductive functions or to functions of CCAP on the oviducts during ecdysis. The oviducts appear more sensitive to CCAP when compared with previously published reports of CCAP actions on the hindgut. CCAP actions on the amplitude of neurally-evoked contractions of the oviducts are similar to those of proctolin, however, the oviducts are more sensitive to CCAP. No CCAP-like immunoreactive structures were discovered in the nerves innervating the oviducts, or on the oviducts themselves, confirming the previously published suggestion (Dircksen et al., 1991) that CCAP acts as a neurohormone at the oviducts. Cells showing CCAP-like immunoreactivity were discovered in the fat body associated with the oviducts and represent a potential source of CCAP, along with CCAP released from the transverse nerve and perivisceral organs.

Journal Article↗

Early embryonic development in the Djungarian hamster (Phodopus sungorus) is accompanied by alterations in the distribution and intensity of an estrogen (E2)-dependent oviduct glycoprotein in the blastomere membrane and zona pellucida and in its association with F-actin.

The luminal environment of the estrogen (E2)-dominated mammalian oviduct generates and sustains the environment in which the first embryonic cleavages take place. The objective of this study was to determine, by use of an antiserum against an E2-dependent sheep oviduct secretory glycoprotein (M(r) 90,000-92,000), whether the E2-dominated and pregnant oviduct of the Djungarian hamster (Phodopus sungorus) releases an antigenically related protein. If the protein was present, a secondary objective was to define its fate and association with filamentous-actin (f-actin) and chromatin patterns in early cleavage-stage embryos. Oviduct flushings containing embryos (1-cell fertilized, 2-, 4-, and 8-cells), and uterine flushings (> 16 cell embryos) were obtained from pregnant hamsters. Embryos were removed from flushings, and oviduct secretions were analyzed by Western blotting. The zona pellucida was removed with acid Tyrode's solution from approximately half of the 2-, 4-, and 8-cell embryos. Zona-intact and zona-free embryos were then fixed and subjected to triple immunofluorescence staining with an antiserum to the sheep oviduct protein, rhodamine phalloidin, and Hoechst 33258. An antigenically related protein M(r) 200,000) was detected in oviduct secretions of E2-treated, ovariectomized, and pregnant hamsters, and not in secretions from ovariectomized controls. In the zona pellucida of 1- and 2-cell embryos, the oviduct protein displayed an intertwining, reticular organization that was replaced by a diffuse and more intense accumulation in 4-, 8-, and > 16-cell embryos. In 2-cell embryos, punctate foci of the oviduct protein were distributed unevenly over the apical blastomere plasma membrane, forming patches in regions of f-actin exclusion, which were absent at later development stages. At the 4- and 8-cell stage of development, as blastomeres lost their spherical form by minimizing intercellular spaces, the oviduct protein took on a polarized arrangement and was intensely concentrated on membrane areas involved in cell-cell contact that were also the focus of f-actin. These data show that in early cleavage-stage hamster embryos, the intensity and pattern of staining for an E2-dependent oviduct protein (M(r) 200,000) that is released into the oviduct lumen during embryo transport can be distinguished on the basis of membrane f-actin display and blastomere number and shape. These events may mediate cellular processes related to blastomere cleavage, shaping, and/or adhesion that occur in the oviduct.

Actins↗

Angiotensin II and atrial natriuretic peptide in the cow oviductal contraction in vitro: direct effect and local secretion of prostaglandins, endothelin-1, and angiotensin II.

Angiotensin II (Ang II) and atrial natriuretic peptide (ANP) may be involved in local regulation of the oviductal contraction during the estrous cycle. Thus, the in vitro effects of Ang II and ANP on the secretion and contraction of bovine oviduct during the follicular, postovulatory, and luteal phases were investigated. An in vitro microdialysis system (MDS) was utilized to determine the intraluminal release of prostaglandins (PGs), Ang II, and endothelin-1 (ET-1) from the bovine oviducts as well as to observe the effect of Ang II and ANP on the local secretion of these substances. The basal release of PGs, ET-1, and Ang II was higher (P < 0.05) during the follicular and postovulatory phases than during the luteal phase. Stimulation by infusion of Ang II (10(-6) M) or ANP (10(-7) M) into the MDS was carried out for 4 h between 4 and 8 h of incubation. In the oviducts from the follicular and postovulatory phases, the infusion of ANP increased the release of Ang II, but not of ET-1. Infusion of Ang II stimulated the release of ET-1. Both Ang II and ANP increased PGE(2) and PGF(2alpha) release. In the contraction study, direct administration of Ang II (10(-7) M) or ANP (10(-8) M) into the medium during the follicular and postovulatory phases increased the amplitude of oviductal contraction. In contrast, these substances did not show any effect in the contraction and secretion of oviducts from cows during the midluteal phase. These results indicate that during the periovulatory period, Ang II and ANP stimulate the contractile amplitude of the oviduct in vitro. In addition to their direct action on oviductal contraction, Ang II may activate oviductal secretion of ET-1 and PGs. Likewise, ANP stimulates oviductal secretion of PGs and Ang II. Hence, the overall results suggest the existence of a functional endothelin-angiotensin-ANP system in the bovine oviduct during the periovulatory period, which may regulate the oviductal contraction to ensure maximum efficiency of gamete/embryo transport through the oviduct.

Angiotensin II↗

Phospholipid transfer protein (PLTP) mRNA expression is stimulated by developing embryos in the oviduct.

In mammal, fertilization and early preimplantation embryo development occurs in the oviduct. Evidence is accumulating that the oviductal epithelia secrete various biomolecules to the lumen during the secretory phase of the estrus cycle to enhance embryo development. This secretory activity of the oviduct is under the regulation of steroid hormones. Observations also suggested that the gametes and embryos modulate the physiology and gene-expressing pattern of the oviduct. However, the underlying molecular changes remain elusive. We hypothesize that the developing embryos interact with the surrounding environment and affect the gene expression patterns of the oviduct, thereby modulating the oviductal secretory activity conducive to the preimplantation embryo development. To test this hypothesis, suppression subtractive hybridization (SSH) was used to compare the gene expressions in mouse oviduct containing transferred in vitro cultured preimplantation embryos with that of oviduct containing oocytes during the preimplantation period. We reported here the identification and characterization of phospholipids transfer protein (PLTP), which is highly expressed in the embryo-containing oviduct and localized at the oviductal epithelium by in situ hybridization. PLTP contains signal peptide putative for secretory function. More importantly, PLTP mRNA increases in the oviductal epithelia of pregnant, but not pseudo-pregnant mice when assayed by real-time PCR. Taken together, our data suggested that PLTP may play important role(s) during in vivo preimplantation embryo development. This molecule would be a target to delineate the mechanisms and the roles of oviductal secretory proteins on early embryonic development.

Animals↗

The zona pellucida binds the mature form of an oviductal glycoprotein (oviductin).

The use of a monoclonal antibody (MAb) specific for the oviductal zona pellucida (ZP) of the hamster has demonstrated that a new antigen (oviductin) is acquired by the ZP during transit of the oocyte in the oviduct. The epitope that is recognized by the MAb bears a terminal N-acetyl-D-galactosamine residue. We conducted a study in order to determine whether this immunoreactivity of the oviductal ZP results from the addition of the terminal sugar residue to a preformed ZP protein or from the transfer of the mature glycoprotein produced by oviductal secretory cells. We measured the incorporation of [35S]methionine into proteins using four different incubation systems: cumulus oophorus (CO) alone, CO in the presence of oviductal fluid, CO co-incubated with empty oviducts, and CO within intact oviducts. At the end of the incubation period, the ZP, vitelli, dispersed cumulus without oocyte, oviducts, and culture medium were isolated and analyzed for their protein content by sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), autoradiography, and immunodetection. The cumulus cells synthesized several proteins, independently of the oviductal environment; however, none of these proteins corresponded to oviductin. The ZP and the vitelli of cumulus oophorus that were incubated either alone or in the presence of oviductal fluid did not contain radioactive oviductin. When the oviduct (empty or intact) was present in the incubation system, radiolabeled oviductin was synthesized and secreted into the incubation medium. The ZP picked up a detectable amount of radioactive antigen only in the system in which intact oviducts were incubated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Demonstration, localization, and development of galanin receptors in the quail oviduct.

We recently isolated an oviposition-inducing peptide that was identified as avian galanin from the oviducts of the Japanese quail. Avian galanin was localized in neural fibers distributed in muscle layers in the uterine and vaginal oviduct regions, and potentiated spontaneous contractions of the uterus and vagina. To elucidate whether an oviposition-inducing effect of avian galanin is due to the direct action on the oviduct, therefore, a specific binding site for avian galanin was determined in the functional quail oviduct in this study. The binding of [125I]iodoavian galanin was primarily located in the oviduct as well as the brain. The galanin binding was specifically inhibited as a function of the concentrations of both avian and rat galanins. The specific binding of avian galanin to the quail oviduct was temperature dependent and reached the maximum level for 1 h at 20 degrees C. In several regions of the oviduct, a higher level of specific galanin binding was observed only in the uterus and vagina. In contrast, the specific binding was low in the isthmus and negligible in the magnum. A similar localization was evident in the functional chicken oviduct. The Scatchard plot analysis of the binding of avian galanin to the uterine preparation revealed that the dissociation constant (Kd) was 0.249 (95% confidence interval, 0.192-0.356) nM, and the number of binding sites was 1.13 (0.99-1.36) fmol per mg tissue, respectively. During development, the galanin-binding sites were apparent in the quail oviduct at 3 weeks of age and the number of binding sites markedly increased between 3 weeks and 3 months of age. However, there was no significant change in the Kd value in the developing quail oviduct. This is the first demonstration of the presence of galanin receptors in the reproductive tract, such as the uterine and vaginal oviduct. The present results suggest that the number of galanin receptors in the oviduct increases during development and that galanin acts directly on the mature uterus and vagina to induce their contractions. This mechanism may be essential to the avian oviposition.

Aging↗

Composition and morphology of lipid droplets from oviduct epithelial cells.

This study was undertaken to determine the composition and morphology of lipid droplets in situ and isolated from oviductal epithelial cells and oviductal fluid. Oviductal epithelial cells were harvested enzymatically from oviducts of cows in either the luteal or the follicular stages of the ovarian cycle. Lipid droplets were isolated from cellular homogenates and characterized biochemically using thin layer chromatography. The morphology of lipid droplets in oviductal epithelial cells and in fractions isolated by ultracentrifugation from cellular homogenates was examined by electron microscopy. Lipid droplets isolated from oviduct epithelial cells varied in composition with the ovarian cycle and the oviductal region. There was more total lipid in droplets isolated from cows in the luteal than follicular phase of the ovarian cycle. Most of this difference was due to large amounts of esterified cholesterol present in the samples from luteal-stage animals. The most esterified cholesterol was found in droplets isolated from the oviductal isthmus of luteal cows. Droplets similar in lipid composition to those isolated from epithelial cells were found in oviductal fluid. Four distinct types of lipid inclusions were evident in electron micrographs of oviductal epithelia and characterized as osmiophilic droplets, lipofuscin-like clusters, lamellar structures, and composite bodies. All of the lipid inclusions were found in droplet isolates except for the extracted lipid portion of the composite body. The presence and diversity of oviduct epithelial lipid inclusions suggest that the oviductal epithelium may be very active in lipid metabolism, particularly cholesterol dynamics.

Animals↗

Co-culture of ovine eggs with oviductal cells and trophoblastic vesicles.

Three experiments were conducted to determine whether coculture of early sheep eggs with oviductal cells would improve the ability of eggs to survive in culture. Eggs recovered from superovulated ewes were cultured in Ham's F-10 medium supplemented with 10% fetal calf serum (F10FCS) at 37.5 degrees C in 95% air:5% CO(2). In Experiment 1, eggs with one to eight cells were either transferred into recipient ewes immediately after collection or were cultured for 24 h in 5 ml Ham's F10 medium supplemented with 10% fetal calf serum (F10FCS), 5 ml F10FCS on a confluent monolayer of oviductal cells; in 25 ml of fresh F10FCS; or in 25 ml of F10FCS removed cultures of oviductal cells, 25 mul of fresh F10FCS or 25 mul of F10FCS removed from cultures of oviductal cells. After 24 h, the cultured eggs were transferred to recipient ewes synchronous with donors and subsequently recovered at necropsy on Day 8 post estrus. Coculture of sheep eggs with oviductal cells improved (P < 0.05) the development of transferred eggs compared to culture in F10FCS alone. In Experiment 2, eggs recovered from superovulated ewes on Days 3 to 6 after estrus had undergone 1.8 cleavages by Day 3 and 4.1 cleavages by Day 6. In Experiment 3, single-cell eggs were cultured for 3 d in 5 ml F10FCS, cocultured with ovine trophoblastic vesicles or cultured on a confluent monolayer of oviductal cells. Coculture of eggs in F10FCS on a monolayer of oviductal cells supported in vitro egg cleavage to a greater degree than did F10FCS alone or F10FCS with trophoblastic vesicles (P < 0.05). In Experiment 4, single-cell eggs were cultured for 3 d then transferred to recipients. Eggs were cultured in 5 ml F10FCS on confluent monolayers of oviductal cells from luteal or estrous ewes or on cells that had been frozen after recovery from a culture of oviductal cells. After culture, the eggs were transferred to oviducts of recipients and recovered 3 d later at necropsy. Coculture of eggs for 72 h with oviductal cell monolayers did not increase the in vitro, or subsequent in vivo, cleavage rate regardless of the type of oviductal cells.

Journal Article↗