Behavior of bull spermatozoa in bovine uterine tube epithelial cell co-culture: An in vitro model for studying the cell interactions of reproduction

Sperm-fluid-cell interplays in the bovine oviduct: glycosaminoglycans modulate sperm binding to the isthmic reservoir

When entering the oviduct for fertilisation, spermatozoa come into contact with the oviduct fluid (OF) and can bind to luminal epithelial cells in the isthmus to form a sperm reservoir. The objective of this study was to examine how the OF modulates sperm adhesion to the oviduct reservoir using an in vitro model of oviduct epithelial spheroids (OES). Bovine oviducts from a local slaughterhouse were used to collect OF and isthmic fragments for the in vitro incubation of OES. Compared to a non-capacitating control medium, the pre-ovulatory OF significantly decreased by 80-90% the density of spermatozoa bound to OES without affecting sperm motility, membrane integrity, or sperm-cilia interactions. This effect on sperm binding was reproduced with (1) OF from different cycle stages and anatomical regions of the oviduct; (2) OF fractions of more than 3 kDa; (3) modified OF in which proteins were denatured or digested and (4) heparan sulphate but not hyaluronic acid, two glycosaminoglycans present in the OF. In conclusion, the OF significantly decreased the number of spermatozoa that bind to oviduct epithelial cells without affecting sperm motility and this effect was due to macromolecules, including heparan sulphate.

Steroid hormones regulate sperm-oviduct interactions in the bovine

After insemination in the cow, a sperm reservoir is formed within the oviducts, allowing the storage and then progressive release of spermatozoa toward the ovulated oocyte. In order to investigate the hormonal regulation of these events in vitro, the ovarian steroids 17β-estradiol (E2) and progesterone (P4) were added at various concentrations to monolayers of bovine oviduct epithelial cells (BOEC) before or during co-incubation with spermatozoa. Main findings demonstrate that (1) a 18-h pretreatment of BOEC with 100 pg/mL and 100 ng/mL of E2 decreased by 25% the ability of BOEC to bind spermatozoa after 10 min, and for the highest dose of E2, 60 min of co-incubation; (2) P4 at concentrations of 10, 100 and 1000 ng/mL induced the release within 60 min of 32-47% of bound spermatozoa from BOEC; this sperm-releasing effect was maintained after a 18-h pretreatment of BOEC with 100 pg/mL of E2; (3) E2 in concentrations above 100 pg/mL inhibited the releasing effect of P4 on bound sperm in a dose-dependent manner; (4) spermatozoa bound to BOEC, then released from BOEC by the action of P4-induced higher cleavage and blastocyst rates after in vitro fertilization than the control group. These results support the hypothesis that the dynamic changes in steroid hormones around the time of ovulation regulate the formation of the sperm reservoir and the timed delivery of capacitated spermatozoa to the site of fertilization.

Optimisation of proteomic approaches to study the maternal interaction with gametes in sow's reproductive tract

The applications of 2DE and MS have been successfully used in many studies utilising different biological samples. The complex nature of cellular proteomes is a big challenge for proteomic technologies. Much effort has been applied to develop and improve the preparation techniques for proteomic samples to be able to detect the low abundant proteins. This is one of the major and unsolved challenges facing the proteomic analysis of biological samples. One partial remedy is to deplete the proteomic samples. In this study, we compared two techniques (acetone precipitation and commercial kit) for the cleaning and purification of oviductal and uterine horn secretory proteomes in primary cell culture system. The samples prepared from acetone precipitation and commercial kit 2-D clean up kit were compared by 2-dimentioanl electrophoresis. We found that no significant difference was observed in number of spots detected between the samples prepared by acetone precipitation technique to those prepared by commercial kit. Protein samples were run through strong cation exchange (SCX) liquid chromatography in order to fractionate samples of major proteins. Protein identification by mass spectrometry revealed a significant detection of low abundant proteins in comparing to high abundant proteins. In conclusion, acetone precipitation was found to be more efficient and cost effect technique. Depletion of proteomic samples from the most abundant protein species is strongly recommended to allow the mid and low abundant protein to be detected. A better resolution of the gels will be achieved by removing the major proteins such as albumin and immunoglobulin.

Bovine oviductal epithelial cells: their cell culture and applications in studies for reproductive biology

Epithelial cells of the mammalian oviduct play an important role in reproductive and developmental events that occur there. Oviductal epithelial cells from several mammalian species can be isolated and cultured in serum or serum-free medium in vitro and cell culture of bovine oviductal epithelial cells (BOEC) has been described by many investigators. Cultured BOEC show a wide variety of secretory activities and these secretory factors may influence early embryonic development or sperm function. Monolayer cultures of BOEC have been widely used for in vitro co-culture of bovine preimplantation embryos. The use of BOEC co-culture systems has improved embryonic development in nearly all the studies conducted. In addition, interaction of bovine spermatozoa with BOEC, in a similar manner to that observed for spermatozoa in vivo, induced specific changes in sperm capacitation and consequently improved the fertilizing capacity of bovine spermatozoa in vitro. Thus co-culture systems with BOEC may not only offer an excellent model for studying the mechanisms of capacitation and acrosome reaction of bovine spermatozoa but also provide a useful tool for the improvement of embryo development in vitro.

Oviductal cells and early conception

The ability to bypass the oviduct by fertilizing human oocytes in vitro and then transferring the ensuing embryos into the uterine environment to produce pregnancies that can be carried to term (assisted reproductive technology, ART) has made the real functional significance of the fallopian tube come under debate. The question has been raised as to whether the oviduct is a simple conduit, providing for the transport of gametes and embryos, or whether it has any functional relevance to early conception. In the field of ART, some reports claim that transfer of embryos either to the uterus or to the oviduct yield similar results, while a greater amount of evidence confirms that tubal transfers are associated with higher pregnancy and take home baby rates, suggesting that unknown factors in the oviduct favour fertilization and embryo viability. This review attempts to provide some answers to questions about the role of oviductal cells in vivo during early conception and in vitro in the field of ART.

In vivo versus in vitro fertilization

The complex sequence of biological steps involved in reproduction in vivo is only partially reproduced in current IVF procedures. In fact, events playing a key role in vivo such as male gamete selection can only be partially mimicked in vitro. To understand the role played by the mammalian oviduct in sperm storage and selection several in vitro sperm-oviductal cell co-culture systems have been developed. Particular sperm subpopulations have been reported to be selected by in vitro cultured oviductal cells through cell-cell adhesion, in different species. In the bovine, in vitro selected sperm have been demonstrated to be endowed with a superior zona pellucida binding and fertilization competence. In conclusion, research on in vitro sperm oviduct interaction may provide new basic information about early reproductive events allowing the development of alternative methods for a more physiological sperm selection in assisted reproductive biotechnologies.

Effect of Bovine Oviduct Epithelial Cell Apical Plasma Membranes on Sperm Function Assessed by a Novel Flow Cytometric Approach1

In the bovine, as in many mammalian species, sperm are temporarily stored in the oviduct before fertilization by binding to the oviduct epithelial cell apical plasma membranes. As the oviduct is able to maintain motility and viability of sperm and modulate capacitation, we propose that proteins present on the apical plasma membrane of oviduct epithelial cells contribute to these effects. To verify this hypothesis, the motility of frozen-thawed sperm was determined after incubation for 6 h with purified apical plasma membranes from fresh or cultured oviduct epithelial cells or from bovine mammary gland cells as a control. Analysis of intracellular calcium levels was performed by flow cytometry on sperm incubated with fresh membranes using Indo-1 to assess the membrane effect on intracellular calcium concentration. The coculture of sperm with fresh and cultured apical membranes maintained initial motility for 6 h (65% and 84%, respectively). This effect was significantly different from control sperm incubated without oviduct epithelial cell apical membranes (23%), with mammary gland cell apical membranes (23%), or with boiled epithelial cell apical membranes (21%). Apical membranes from oviduct epithelial cells diminished the percentage of sperm that reached a lethal calcium concentration over a 4-h period (18.7%) compared with the control (53.8%) and maintained lower intracellular calcium levels in viable sperm. These results show that the apical plasma membrane of bovine oviduct epithelial cells contains anchored proteinic factors that contribute to maintaining motility and viability and possibly to modulating capacitation of bovine sperm.

Effects of canine oviduct epithelial cells on movement and capacitation of homologous spermatozoa in vitro

In this study, the interaction between canine sperms and oviduct epithelial cells (OECs) was examined in vitro. The oviducts of eight bitches in the follicular (F-) phase and six bitches in the luteal (L-) phase were removed under halothane inhalation anesthesia. The entire oviduct was opened longitudinally, and the oviductal epithelium of bitches in the F- and L-phases was scraped with a scalpel into tissue culture medium (Eagle's MEM) containing 10% estrous bitch serum and 10% diestrous bitch serum, respectively. The OEC collected were preincubated for 24h and then coincubated with ejaculated canine sperms at 38 degrees C under an atmosphere of 5% CO2 in air. The percentages of sperms exhibiting active tail movement (% TM), hyperactivated sperms (% HA), and acrosome-reacted sperms (% AR) were investigated until 72 h after the start of coincubation. The percentage of sperms labeled with fluoresceinated Ca indicator (% Ca) was evaluated to assess the influx of Ca into sperms cytoplasm during capacitation. Canine sperms attached to both ciliated OEC and non-ciliated OEC. All of the mean % TM of the OEC-binding sperms in the F-OEC and L-OEC media after 24, 48, and 72 h of coincubation were significantly higher than the values of the freely swimming sperms (P< or =0.01). Conversely, the mean % AR and % Ca of the OEC-binding sperms were significantly lower (P<0.01). All of the mean % HA and % AR of the freely swimming sperms in the F-OEC medium after 24, 48, and 72 h of coincubation were significantly higher than the values of the sperms in the L-OEC medium (P< or =0.01). These results indicate that attachment of canine sperms to the OEC prolongs their viability and motility arid inhibits Ca influx into the sperms and sperm capacitation. These phenomena may be responsible for maintaining the active movement and the fertile life of canine sperms in homologous oviducts.

Heparin and Ca2+-free medium can enhance release of bull sperm attached to oviductal epithelial cell monolayers

The success of assisted reproductive techniques, such as IVF, could be enhanced by being able to select the most competent spermatozoa in a sample. Attachment and subsequent release of spermatozoa from oviductal epithelial cells (OEC) could provide populations of functionally superior spermatozoa for use in these protocols. The objective of the present study was to investigate the ability of heparin and Ca2+-free medium to induce spermatozoa release from bovine OEC. Epithelial cells were grown to confluence in 24-well plates and pooled frozen bull semen was added to a final concentration of 1 x 10(6) spermatozoa/well. Spermatozoa were allowed to bind to OEC for 2 h. Medium with unbound spermatozoa was removed and replaced by Sperm-TALP, only (control), with heparin (5, 10, or 15 IU/mL), or Ca2+-free with 2 mM EGTA. Treatments were left on sperm-OEC co-cultures for 0.5, 1, 2, 3, or 5 h. At each time, the media were recovered and spermatozoa from each treatment were counted and evaluated for acrosome integrity and motility. The total number of spermatozoa attached to OEC after 2 h of co-culture was considered 100%. Spermatozoa release is expressed as percentage of the total number of sperm cells bound to OEC after 2 h of co-culture. Data were analyzed by ANOVA and results are expressed as mean +/- SEM from three independent replicates. Beginning at 0.5 h, more sperm cells (P < 0.05) were released from OEC in the heparin groups (10 and 15 IU/mL, 77.3 +/- 6.2% and 84.0 +/- 6.2%, respectively) as compared to the control (46.4 +/- 6.2%). The Ca2+-free medium also induced spermatozoa release when compared with the control, but the effect was not significant until 3 h (38.2 +/- 1.9% vs 59.5 +/- 6.9%; P < 0.05). The percentage of acrosome reacted spermatozoa was not affected by heparin treatment. Heparin at 10 IU/mL increased (P < 0.05) the percentage of motile spermatozoa, whereas Ca2+-free medium caused the opposite effect at 0.5 h after addition of treatments. We conclude that both heparin and Ca2+-free medium are able to promote spermatozoa displacement from OEC attachment. Based on motility and acrosome status data, we predict that released sperm cells may be used for IVF and other assisted reproductive techniques.

Sulfated glycoconjugates are powerful modulators of bovine sperm adhesion and release from the oviductal epithelium in vitro

The mechanisms of sperm adhesion and release within the mammalian oviduct are still poorly understood. In this in vitro study, a previously developed adhesion assay was used to analyze the effects of heparin, N-desulfated heparin, fucoidan, dextran sulfate, and dextran on bovine sperm-oviductal cell adhesion and release. Results showed that 1) all sulfated glycoconjugates were powerful inhibitors of sperm binding to oviductal monolayers in a dose-dependent manner, whereas N-desulfated heparin and dextran had no effect; 2) sperm pretreatment with heparin and fucoidan markedly inhibited adhesion; 3) treatment of oviductal monolayers with heparinase I, II, or sodium chlorate (an inhibitor of sulfation) had no effect on sperm adhesion; 4) sulfated glycoconjugates were also powerful and quick inducers of sperm release from oviductal monolayers; and 5) addition of sulfated glycoconjugates to the cocultures caused a sudden increase of bound-sperm flagellar beat frequencies, followed by a release of highly motile sperm. In conclusion, these data support the hypothesis that sulfated glycoconjugates may act as signals that induce sperm release and migration from the oviductal reservoir.

Contact of dog spermatozoa with homologous uterine tube epithelium prolongs flagellar activity in relation to the stage of the estrous cycle

There is scant information about the storage of spermatozoa within the reproductive tract of the bitch. In several species the uterine tube plays a significant role in sperm storage. The present study was performed to investigate the interaction between spermatozoa and the epithelium of the uterine tube, in particular how this interaction might influence the flagellar activity of spermatozoa in relation to the stage of the estrous cycle. Epithelium was harvested from uterine tubes of 24 bitches at various stages of the estrous cycle (estrus, luteal phase or anestrus), and cultured with pooled spermatozoa collected from 6 dogs. Spermatozoa rapidly bound to the epithelial surface by their heads and the majority of attached spermatozoa were motile. The intimate association between spermatozoa and the uterine tube epithelium maintained motility in a manner that was related to the stage of the estrous cycle. Flagellar activity was significantly greater for spermatozoa bound to estrous epithelium than epithelium from the luteal phase or anestrus. On average, approximately 10% of spermatozoa that were attached to the uterine tube epithelium of estrous bitches retained their flagellar activity for 48 h after innoculation. There was no apparent influence of the region of the uterine tube on this effect. These findings suggest that the uterine tube may form a functional spermatozoal reservoir in the bitch.

In vitro-cultured bovine oviductal cells bind acrosome-intact sperm and retain this ability upon sperm release

The mammalian oviduct plays a key role in sperm storage, capacitation, and selection. Specific oviduct secretions and/or binding to oviductal cells are thought to be responsible for the extension of the fertile life span of sperm. In this in vitro study, a quantitative assay for sperm binding was developed to analyze the mechanisms of sperm-oviductal cell adhesion and release in the bovine species. Distribution and acrosomal status of sperm bound to in vitro-cultured ampullary and isthmic cell monolayers were followed until the time of sperm release by means of fluorescence labeling techniques. In order to understand whether release is due to surface changes of sperm or oviductal cells, double incubation experiments with unlabeled and Hoechst-labeled sperm have been performed. Main findings demonstrate that (1) only acrosome-intact sperm bind specific bovine oviductal epithelial cells; (2) acrosomes of bound sperm are preserved intact over time; and (3) release of unreacted sperm is likely to be due to changes of the sperm surface, probably triggered by capacitation. These findings support the hypothesis that binding to oviductal cells is essential for preserving the sperm fertilization competence during the interval from the onset of estrus to ovulation.

Effects of 17beta-oestradiol or oestrous stage-specific cow serum on the ability of bovine oviductal epithelial cell monolayers to prolong the viability of bull spermatozoa

The effect of 17beta-oestradiol and oestrous stage-specific cow serum on bovine oviductal epithelial cell monolayers to extend the viability of co-cultured bull spermatozoa was examined. Monolayers of cells from ampullary and isthmic segments were pre-treated with medium containing either oestrous cow serum, luteal-phase cow serum, 1 microg/ml 17beta-oestradiol + foetal bovine serum or foetal bovine serum alone (control) before the addition of motile frozen/thawed spermatozoa. Motility was visually assessed throughout a 48 h co-incubation period, while fertilising ability of spermatozoa was evaluated by adding in vitro matured bovine oocytes. Pre-treatment with 17beta-oestradiol or oestrous cow serum resulted in a higher percentage of motile spermatozoa after 18 h in isthmic and after 36 h in ampullary cultures compared with the control, but pre-treatment did not affect fertilisation rates. Only at 42 h in ampullary cultures was motility higher in luteal serum pre-treated cultures compared to the control. Motility was also assessed in medium conditioned by pre-treated monolayers. Pre-treatment with 17beta-oestradiol enhanced the ability of conditioned medium to prolong motility and medium conditioned with oestrous cow serum was superior to medium conditioned by luteal-phase serum at maintaining motility. In conclusion, the ability of oviductal epithelium to prolong the motility of spermatozoa is enhanced by 17beta-oestradiol.

Relationship between bull field fertility and in vitro embryo production using sperm preparation methods with and without somatic cell co-culture

Experiments were designed to compare rates of embryonic development following oocyte exposure to cryopreserved spermatozoa from bulls of varying proven fertility, utilizing 3 different sperm preparation methods prior to oocyte introduction. These included 1) sperm co-culture with bovine oviductal epithelial cells (BOEC); 2) sperm co-culture with buffalo rat liver cells (BRLC); or 3) control culture in a routine, cell-free culture system. Semen from 9 bulls was classified by lifetime 60- to 90-d nonreturn rates as having either (mean +/- SEM) high (n=3) 73.2 +/- 3a, medium (n=3) 70.3 +/- 2b or low (n=3) 65.8 +/- 3c field fertility ((ac)p< 0.01; (bc)p< 0.05). There was no difference in embryo cleavage rates for spermatozoa from the high (58 +/- 18%), medium (57 +/-23%) or low (57 +/- 18%) fertility groups. Development to morula or beyond of oocytes fertilized with high (53 +/- 30%) or low (58 +/- 27%) fertility semen tended (P<0.10) to be higher than of those fertilized with medium fertility (33 +/- 28%) semen. This lack of relationship between in vivo fertility and in vitro embryo outcome was consistent across all sperm preparation methods. Therefore, pooled data were used to evaluate the effect of sperm preparation on embryo outcome. There was no difference in embryo cleavage rates between BOEC monolayers (51 +/- 22%), BRLC monolayers (60 +/- 20%) and the cell-free controls (60 +/- 17%). Subsequent embryonic development to compact morula and beyond was higher (P<0.01) with the BRLC monolayer treatment (61 +/- 28%) than with the BOEC monolayers (42 +/- 33%) or control culture (39 +/- 24%). In conclusion, these studies suggest that there is no predictive relationship between bull field fertility (in the ranges evaluated here) and in vitro embryo cleavage or development rates. However, oocytes inseminated with sperm cells co-cultured on BRLC monolayers develop to the morula stage or beyond at a higher rate than oocytes inseminated with spermatozoa from the BOEC or cell-free system.

Membrane integrity and fertilizing potential of cryopreserved spermatozoa in European mouflon

There is a pressing need to develop and use assisted reproductive techniques in wildlife species living in small and captive groups. We evaluated the effect of freezing on membrane integrity and fertilizing capacity of European mouflon (Ovis gmelini musimon) spermatozoa collected during the breeding season. After thawing, the percentage of live spermatozoa, stained with fluorescein isothiocynate labeled Pisum Sativum agglutinin and propidium iodide, was 47% of which 19% showed intact acrosomal membrane. After culture in TCM 199 + 10% FCS, the number of live spermatozoa was significantly (P < 0.01) lower than in a medium with oviductal epithelial cells. The absence of oviductal cells decreased significantly the fertilization rates (P < 0.05), 24.0 vs. 63.1 with oviductal epithelial cells and 59.1 in vivo of in vitro matured ovine oocytes. Polyspermic fertilization rate of oocytes was lower (P < 0.05) with oviductal epithelial cells (1.6) than in absence of cells (12.8). However, the percentage of embryos that reached blastocyst stage was significantly higher in vivo than in vitro. These results provide interesting preliminary data for the development of genetic resource banks for European mouflon.

Induction of dog sperm capacitation by oviductal fluid

Four estrous beagles were inseminated with 1 x 10(8) sperm into both the right and left uterine horns, and the uterine horn and oviduct on one side were removed under anesthesia after 7 hr and 24 hr, respectively. The lumen of the uterine horns and oviducts was flushed with canine capacitation medium (CCM), and movement of the sperm in CCM was assessed by phase-contrast microscopy. In a second experiment, ejaculated sperm obtained from 5 normal beagles was incubated in CCM supplemented with oviductal flush fluid (OF-CCM) at 38 degrees C with 5% CO2 in air. Motility of sperm, and percentages of hyperactivated sperm (%HA) and acrosome-reacted sperm (%AR) among freely swimming (FS) sperm were investigated until 24 hr after the start of incubation. After 7 hr of incubation the sperm was coincubated with canine oocytes in OF-CCM for 2 hr, and the number of zona pellucida-binding (zona-binding) sperm was then counted. The %HA among the sperm in the oviductal flush fluid both 7 hr (mean +/- S.E.; 15.0 +/- 2.4%) and 24 hr (77.5 +/- 5.2%) after intrauterine insemination were significantly higher than in the uterine flush fluid (P < 0.05, 0.01, respectively). The motility and %HA among FS-sperm in OF-CCM were higher than in the control medium without oviductal fluid. However, there was no difference in the %AR between OF-CCM and control medium. The number of zona-binding sperm in OF-CCM (8 +/- 1) was significantly greater than in control medium (5 +/- 1) (P < 0.05). These results suggest that oviductal fluid in the estrous bitch maintains sperm motility and induces sperm capacitation.

Isolation and characterization of a protein with homology to angiotensin converting enzyme from the periacrosomal plasma membrane of equine spermatozoa

The periacrosomal plasma membrane of spermatozoa is involved in sperm binding to oviductal epithelial cells and to the zona pellucida. A protein of 68-70 kD molecular mass was purified biochemically from the isolated periacrosomal plasma membrane of equine spermatozoa as a possible receptor for adhesion of spermatozoa to oviductal epithelial cells. A polyclonal antibody raised in rabbits against the purified equine sperm membrane protein recognized the 70 kD and an antigenically related to 32 kD protein in preparations of isolated periacrosomal sperm plasma membrane and in detergent extracted ejaculated and epididymal spermatozoa. A larger protein (approximately 110 kD) was detected in equine testis. Two antigenically related proteins (64 and 45 kD) were recognized on the plasma membrane of cynomolgus macaque spermatozoa. In vitro sperm-binding assays were performed in the presence of antigen-binding fragments or IgG purified from the polyclonal antiserum to investigate a possible function to the isolated protein in binding of equine spermatozoa to homologous oviductal epithelial cells or zona pellucida. Incubation with antigen-binding fragments or IgG purified from the antiserum did not inhibit binding of equine spermatozoa either to oviductal epithelial cells or the zona pellucida. On ultrastructural examination, the antibody bound exclusively to the cytoplasmic side of the periacrosomal plasma membrane of equine and macaque spermatozoa. Microsequence analysis of 13 residues of sequence showed strong homology with a number of angiotensin converting enzymes: An 84% identity was identified with testis specific and somatic forms of human and mouse angiotensin-converting enzyme. Immunocytochemistry and immunoblot analysis established that the protein is specific for the periacrosomal membrane of ejaculated, epididymal, and testicular stallion spermatozoa.

Sperm interaction with fallopian tube apical membrane enhances sperm motility and delays capacitation

OBJECTIVE

To understand the effect of sperm contact with the apical plasma membrane of tubal epithelial cells on sperm motility, velocity, and capacitation.

DESIGN

Prospective, controlled in vitro study.

SETTING

University medical center.

PATIENT(S)

Women of reproductive age undergoing hysterectomy for benign gynecologic indications and normozoospermic donors of proved fertility.

MAIN OUTCOME MEASURE(S)

Sperm motility as measured manually, velocity as measured by computer-assisted sperm motility analysis, and capacitation status as measured by the chlortetracycline fluorescence assay.

RESULT(S)

Sperm incubated with apical membrane vesicles had a significantly higher motility at 12 (87.4% +/- 3.4% versus 69.2% +/- 4.8% [mean +/- SEM]), 24 (85.2% +/- 3.1% versus 60.5% +/- 7.2%) and 48 hours (78.9% +/- 5.3% versus 42.4% +/- 11.3%) compared with control (sperm incubated with human tubal fluid media in the absence of apical membrane vesicles) (n = 4). Progressive velocity was significantly higher at 12 (78.2 +/- 1.4 versus 61.7 +/- 16.1 microns/s) and 24 (66.2 +/- 3.9 versus 34.4 +/- 9.8 microns/s) hours (n = 4). Incubation with apical membrane vesicles significantly slowed the transition from uncapacitated to capacitated chlortetracycline fluorescence pattern (n = 5).

CONCLUSION(S)

Contact with the apical plasma membrane of tubal epithelial cells enhances sperm motility and delays sperm capacitation in vitro.

Bovine oviductal epithelial cells (BOEC) and oviducts: I. For embryo culture. II. Using SEM for studying interactions with spermatozoa

The oviduct (uterine tube) plays a major role in reproduction. It is a dynamic organ which selectively permits a few sperm to undergo capacitation and reach the oocyte which has continued to undergo maturation following ovulation. Then following fertilization the embryo undergoes cleavage before arriving in the uterus. Extensive information has become available from in vitro studies on oocytes as well as spermatozoal interactions with oviductal cells. Bovine oviduct epithelial cell (BOEC) monolayers with simple media provide an environment in which zygotes can be cultured to blastocysts in 6 days with cell numbers essentially equivalent to blastocysts grown totally in the donor animal. These yield normal pregnancy rates upon transfer. The simple protein-free media currently under test hold promise for elucidating specific requirements of the preimplantation embryo and these defined conditions facilitate many related studies on in vitro fertilization and genetic engineering of embryos. The second part of this paper is an extensive study on the interaction of fresh and frozen-thawed bull spermatozoa with BOEC and segments of intact oviducts as viewed by SEM. Both types of oviductal cells were incubated at 39 degrees C for 0, 3, 6, and 9 hours, using material obtained from periovulatory cows. Sperm attached immediately to both types of epithelium and reached a peak at 3 hours. They were found primarily in the furrows of the intact oviducts. Secretory droplets appeared rapidly on the anterior portion of the sperm head and acrosomal changes were evident in 3 hours, similar to those reported in vivo. Changes were more rapid with frozen-thawed sperm.

Effect of coculturing spermatozoa with oviductal cells on the incidence of polyspermy in pig in vitro fertilization

It is known that oviductal cells play an important role in fertilization in vivo. We were interested in the effect of those cells on spermatozoa and their influence on the incidence of polyspermy in pig in vitro fertilization (IVF) when cocultured with spermatozoa. Oviductal cells are believed to select a highly fecund population of spermatozoa. By coculturing spermatozoa with oviductal cells it is possible to reduce the number of spermatozoa confronting the eggs at fertilization, reducing the incidence of polyspermy. In our study, spermatozoa were cocultured with oviductal cells for 30 min so that they could bind to the oviductal cells. Both bound and unbound spermatozoa were used for fertilization. The results show that the spermatozoa that were bound to the oviductal cells were capable of fertilizing the eggs, but the nonbound spermatozoa had a reduced penetration incidence. With the bound sperm, polyspermy incidence decreased and the two-pronuclei proportion increased. We also found that with time the spermatozoa released from the cells had better motility than those that did not bind. Therefore, it is our belief that oviductal cells can be used for porcine IVF resulting in a lower polyspermy incidence and higher pronuclei incidence.

Human sperm function after coculture with human fallopian tubal epithelial cell monolayers: in vitro model for studying cell interactions in early human conception

It has been difficult to study the behavior of sperm in the tubal environment in vivo. Human tubal epithelial cells were therefore cultured in vitro to simulate tubal conditions and human sperm function was assessed in the presence of such cells in vitro. Ampullary epithelial cell lines were established from fallopian tubes collected from premenopausal women undergoing hysterectomy. Approximately 1 x 10(5) cells/mL from monolayers of the third passage were seeded with 1 mL of culture medium into each well of 4-well plastic dishes. Sperm from 10 ejaculates of 10 different oligoasthenozoospermic men 30-41 years of age were recovered by the swim-up method and 200,000 sperm from each ejaculate were added into each well at the time of cell seeding. Control wells were treated the same but without cells. All dishes were incubated at 37 degrees C in 5% CO2, and sperm motility, acrosome reaction, and sperm-cell binding assessed at 1, 5, and 24 h. Curvilinear velocity and mean amplitude of lateral head displacement were significantly different in ampullary cultures as compared with controls for all three time periods: 1 h (67 +/- 5.2 vs 58 +/- 4.9 microns/s, p < 0.05; 4.48 +/- 0.4 vs 3.29 +/- 0.3 microns; p < 0.05), 5 h (75 +/- 5.8 vs 64 +/- 5.0 microns/s, p < 0.05; 4.92 +/- 0.5 vs 3.68 +/- 0.3 microns, p < 0.05), and 24 h (70 +/- 4.8 vs 59 +/- 4.2 microns/s, p < 0.05; 4.36 +/- 0.4 vs 3.11 +/- 0.3 microns, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ram spermatozoa cocultured with epithelial cell monolayers: an in vitro model for the study of capacitation and the acrosome reaction

The effects of different epithelial cells, namely, hamster oviduct, sheep oviduct, and pig kidney epithelial cells (IBRS-2), on the viability, percentage of progressive motility (PPM), and acrosome reactions of ejaculated ram spermatozoa were investigated. Sperm aliquots were cultured on cells, cell-conditioned medium 199, or control medium 199. The PPM of unattached spermatozoa was estimated after 0, 3, 6, 9, 12, and 24 hr of incubation at 37 degrees C under 5% CO2 in air. Viability and the occurrence of true acrosome reactions were assessed using a triple-stain technique. Spermatozoa started to attach within 1 hr of coculture with the hamster or sheep oviductal epithelial cell (OEC) monolayers, and these spermatozoa showed vigorous tail motion. No spermatozoa were found to attach to the IBRS-2 monolayer. The PPM of unattached spermatozoa cocultured with the various types of epithelial cell monolayers for 12 hr was significantly higher than that of spermatozoa incubated in conditioned media or medium 199 alone (54% in hamster OEC vs. 40% in conditioned; 68% in sheep OEC vs. 38% in conditioned; 36% in control medium). On the other hand, after 24 hr of incubation, there were no differences in the PPM of spermatozoa cocultured with epithelial cells or incubated in conditioned media. The percentages of cells undergoing a true acrosome reaction reached maximum values (P < 0.05) in spermatozoa incubated for 9 hr in the presence of hamster OEC (22.5%) or for 12 hr on sheep OEC (20.5%) monolayers.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro interaction between oviduct epithelial and equine sperm

Coculture of stallion sperm with monolayers of equine oviductal epithelial cells (OEC) was evaluated. Monolayers were obtained from frozen-thawed OEC. Live sperm attached to the OEC in vitro, whereas sperm killed by heat treatment or glutaraldehyde fixation did not. Sperm attached to OEC showed flagellar motion for 4 d in vitro, during which time they gradually became released. Scanning electron-micrographs showed an intimate association between the sperm and OEC. Incubation of sperm for 4 h with either control, heparinized or OEC-conditioned medium (Tyrode's albumin lactate phosphate) resulted in more incapacitated sperm, as determined by chlortetracycline staining patterns. The OEC-conditioned medium caused similar capacitation-like changes to those seen with heparin. Sperm viability as determined by Hoechst 33258 staining was not significantly affected by media type.

Biochemical changes in bull spermatozoa during capacitation in vitro

To evaluate the metabolic changes of bull spermatozoa (SPZ) during capacitation in vitro, SPZ were incubated for 0, 5 or 10 hours in the presence (co-culture) and absence (control) of monolayers of bovine oviduct epithelial cells, which promote capacitation-like changes in vitro. There was little change in the oxygen uptake of the SPZ after 5 hours, but after 10 hours there was a decrease, particularly in the co-cultured sample. After 5 hours there was little change in the cyclic adenosine monophosphate (cAMP) concentration of the co-culture or control SPZ, but by 10 hours the levels of cAMP decreased in both the co-cultured and control SPZ (P=0.06). The concentration of adenosine triphosphate (ATP) was somewhat decreased after 5 hours in both the co-cultured and control SPZ and the percentage of decline was much higher after 10 hours. Overall, there was no significant change in oxygen uptake or cAMP and ATP levels specifically associated with capacitation of bull SPZ.