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Biomedical subjects

R Santulli

Publications and source records attributed to R Santulli.

At least 19 recordsLinked to original sources
PubMed1992

The effect of testosterone withdrawal and subsequent germ cell depletion on transferrin and sulfated glycoprotein-2 messenger ribonucleic acid levels in the adult rat testis.

We have examined the effects of decreasing intratesticular testosterone concentration and of decreasing germ cell number on levels of transferrin mRNA and sulfated glycoprotein (SGP)-2 mRNA in the adult rat testis. Intact rats received implants of testosterone- and estradiol-filled capsules to suppress LH secretion from the pituitary, thereby suppressing Leydig cell testosterone production. The levels of intratesticular testosterone declined 70% to 20 ng/ml within 3 days, were reduced further to approximately 15 ng/ml by 14 days, and subsequently reached a minimum of about 10 ng/ml. In contrast, the number of elongated spermatids per testis remained unchanged through 14 days, then declined to fewer than 20% of normal between 14 and 28 days, and reached zero by 56 days postimplantation. Likewise, both pachytene spermatocytes and round spermatids declined only after 14 days postimplantation. Northern blots of testicular RNA showed that Sertoli cell transferrin mRNA per testis decreased markedly between 14 and 28 days postimplantation. However, SGP-2 mRNA per testis was unchanged over the time course of the experiment. The decrease in transferrin mRNA, concomitant with germ cell loss, suggests that this mRNA is regulated by the number of germ cells in the testis and not directly by testosterone. In contrast, the constant level of SGP-2 mRNA in the face of reduced intratesticular testosterone and the subsequent loss of germ cells suggests that this mRNA is constitutively maintained in the adult rat testis.

Animals↗
PubMed1992

Temporal gene expression is restored concomitantly with germ cells in the experimentally regressed rat testis.

The present study was designed to examine the effect of hypophysectomy and subsequent testosterone administration on germ cell numbers and germ cell- and Sertoli cell-specific mRNA levels in adult rats. Rats were hypophysectomized and 4 weeks later received 24-cm testosterone-containing polydimethylsiloxane (PDS) implants. Sham-hypophysectomized rats received an empty PDS implant. At 0 and 3 days, and at 1, 2, 4, and 8 weeks, rats were killed. One testis from each rat (n = 4/group) was used to prepare total RNA; the other testis was used to enumerate stage VII-VIII germ cells. cDNA probes for germ cell and Sertoli cell products were used to monitor germ cell- and Sertoli cell-specific mRNAs on Northern blots. Four weeks after hypophysectomy (0 days), preleptotene and pachytene spermatocytes and round and elongating spermatids were reduced in number to 54%, 12%, 1%, and 0%, respectively, of the control values. Testosterone administration caused a time-dependent increase in germ cell numbers; after 8 weeks of testosterone treatment, preleptotene and pachytene spermatocytes and round and elongating spermatids were 75%, 79%, 74%, and 22%, respectively, of control values. Lactate dehydrogenase-C, phosphoglycerate kinase-2, protamine-1, and sulfated glycoprotein-2 mRNA levels (on a per micrograms RNA basis) were 34%, 34%, less than 1%, and 580% of control values, respectively, 4 weeks after hypophysectomy and 79%, 87%, 61%, and 192% of control values, respectively, after 8 weeks of testosterone treatment. Pachytene spermatocyte and round spermatid numbers increased, while Sertoli cell sulfated glycoprotein-2 mRNA levels decreased, with respect to 4 week hypophysectomy values, as early as 3 days after implantation of testosterone capsules. In contrast, germ cell (lactate dehydrogenase-C, phosphoglycerate kinase-2, and protamine-1) mRNA levels increased to the greatest extent between 1-4 weeks after the start of testosterone treatment and, after a short lag period, reflected increases in germ cell type and number. The results indicate that cell-specific mRNAs appear concomitantly with germ cell reappearance in a time-dependent manner in the testes of testosterone-treated hypophysectomized adult rats.

Animals↗
PubMed1991

Regulation of Sertoli cell transferrin and sulfated glycoprotein-2 messenger ribonucleic acid levels during the restoration of spermatogenesis in the adult hypophysectomized rat.

The purpose of this study was to determine whether the levels of sulfated glycoprotein-2 (SGP-2) and/or transferrin mRNA in Sertoli cells responds to testosterone in the adult rat testis and, if so, to distinguish between the effects of testosterone and those of changing populations of germ cells. To this end we have examined changes in the steady state levels of these two mRNAs in relationship to changes in intratesticular testosterone concentration and germ cell numbers after treatment of adult hypophysectomized rats with testosterone. Hypophysectomy for 4 weeks caused intratesticular testosterone concentrations to become reduced from 50 to 3 ng/ml and caused significant reductions in the numbers of testicular spermatozoa (undetectable), round spermatids (nearly undetectable), and pachytene spermatocytes (12% of normal). Intratesticular testosterone concentrations rose to 30 ng/ml within 3 days after implantation of testosterone-containing polydimethylsiloxane capsules into the hypophysectomized rats. Three days after the initiation of testosterone treatment, increases were seen in the numbers of round spermatids (10% of normal) and pachytene spermatocytes (29% of normal). The major increases in the numbers of these cells and of spermatozoa occurred between days 14-56 of testosterone treatment, with pachytene spermatocytes reaching a maximum of 75% of the control level by day 28, and round spermatids and spermatozoa reaching 75% and 21% of the control levels, respectively, by 56 days. The steady state levels of SGP-2 mRNA were not affected by hypophysectomy, testosterone administration, or subsequent increases in germ cell numbers. In contrast, transferrin mRNA levels were reduced by hypophysectomy. As found for SGP-2, transferrin mRNA levels were unresponsive to increased testosterone concentration, but, unlike SGP-2 mRNA, transferrin mRNA increased as germ cells were restored after testosterone administration. These results suggest that SGP-2 mRNA is not regulated by testosterone or germ cells, but that the level of transferrin mRNA is influenced by the interaction of Sertoli and germ cells in the adult rat testis.

Animals↗
PubMed1990

To what extent can spermatogenesis be maintained in the hypophysectomized adult rat testis with exogenously administered testosterone?

In a previous study it was demonstrated that spermatogenesis can be maintained quantitatively with exogenously administered testosterone in adult intact rats that lack LH. The studies described herein were designed to examine the extent to which spermatogenesis can be maintained quantitatively with exogenously administered testosterone in adult rats that lack all pituitary hormones. Adult male rats were hypophysectomized and testosterone was administered at the time of hypophysectomy via sustained release polydimethylsiloxane (PDS) capsules of increasing lengths. We used the PDS capsules to clamp testosterone at defined concentrations within the seminiferous tubule fluid over a 2- to 3-month treatment period. Mean testis weights and advanced spermatid numbers per testis stabilized by 8 weeks of testosterone treatment regardless of testosterone dose. Both testis weight and advanced spermatid number responded to testosterone dose, reaching plateaus of 1.2 g and 170 x 10(6) per testis, respectively. These values were 60% of, and significantly less than, the respective control values. This result was in striking contrast to the results of our previous study of LH-suppressed intact rats, in which exogenously administered testosterone resulted in testis weights and advanced spermatid numbers that plateaued at values not significantly different from those in controls. These different effects of testosterone in intact and hypophysectomized rats occurred despite the fact that the seminiferous tubule fluid testosterone concentrations achieved in the hypophysectomized rats (up to 25 ng/ml) were greater than the minimal testosterone concentration found previously to be required to maintain spermatogenesis quantitatively in LH-suppressed intact rats (13 ng/ml). Taken together, these results demonstrate clearly that intratesticular testosterone doses that are as high as or higher than those that maintain spermatogenesis quantitatively in intact rats lacking LH fail to maintain spermatogenesis quantitatively in rats lacking all pituitary hormones.

Animals↗
PubMed1990

Restoration of spermatogenesis by exogenously administered testosterone in rats made azoospermic by hypophysectomy or withdrawal of luteinizing hormone alone.

The major objective of the studies presented herein was to compare the extent to which exogenously administered testosterone is able to restore spermatogenesis in adult rats made azoospermic by withdrawal of all pituitary hormones (hypophysectomy for 4 weeks) vs. withdrawal of LH alone [testosterone- and estradiol-filled (TE) polydimethylsiloxane implants of 2.5 and 0.1 cm, respectively, for 8 weeks]. In hypophysectornized (Hypox) rats, serum LH and FSH were both undetectable; in the rats that received TE implants, serum LH was undetectable, but FSH was unaffected compared to control values. Seminiferous tubule fluid testosterone concentrations were reduced significantly from their control values of 60-65 to 1.4-1.7 ng/ml in the azoospermic Hypox and TE rats. These rats then received testosterone-filled implants of 4, 12, 18, or 24 cm and were killed 2 months later. In both the Hypox and TE rats, seminiferous tubule fluid testosterone concentrations rose linearly with increasing capsule sizes, and with each of the implant sizes, these concentrations did not differ significantly between the Hypox and TE rats. This made it possible for the first time to examine the effects of comparable intratesticular testosterone concentrations on the numbers of advanced spermatids per testis that could be restored in the azoospermic testes of rats lacking all pituitary factors vs. those lacking only LH. The results that we present demonstrate that the numbers of restored advanced spermatids were consistently and significantly lower in Hypox than in TE rats despite equivalent seminiferous tubule fluid testosterone concentrations. These results provide quantitative conclusive evidence to support the contention that pituitary factors in addition to LH are required for the quantitative restoration of spermatogenesis in the adult rat testis.

Animals↗
PubMed1989

Restoration of advanced spermatogenic cells in the experimentally regressed rat testis: quantitative relationship to testosterone concentration within the testis.

We examined the effect of exogenously administered testosterone (T) on the quantitative restoration of advanced spermatogenic cells in adult rat testes rendered azoospermic by treating rats with polydimethylsiloxane (PDS) implants of T and estradiol (E). Experimental rats received PDS-TE implants for an initial 8-week period; control rats received empty implants. By 8 weeks of PDS-TE treatment, rats became severely oligospermic, and the T concentration within the seminiferous tubule fluid (STF) was reduced approximately 80% (from 57.8 ng/ml in controls to 9.6 ng/ml). After the initial 8-week PDS-TE treatment, PDS-TE implants were removed from one group of rats; a second group of PDS-TE-implanted rats received an additional PDS-T implant of 24 cm. Eight weeks after the removal of PDS-TE implants or the implantation of additional T, testis weight and numbers of advanced spermatogenic cells were restored to those of control rats. The STF T concentration 8 weeks after the removal of PDS-TE implants also was restored to that in control rats. In contrast, the STF T concentration increased to only 40% of control values in the rats that received an additional T implant. Despite this 60% reduction in T concentration compared to the control value, advanced spermatogenic cell number was restored to a value indistinguishable from that of intact controls. These observations indicate that spermatogenesis can be quantitatively restored in PDS-TE-implanted rats with exogenously administered T, and moreover, that this restoration does not require the high T concentration found in the STF of intact control rats.

Animals↗
PubMed1989

Maintenance of advanced spermatogenic cells in the adult rat testis: quantitative relationship to testosterone concentration within the testis.

The studies described herein were designed to examine whether there is a threshold concentration of testosterone (T) within the seminiferous tubules that is required to maintain spermatogenesis in the rat, or alternatively, whether there is a dose-response relationship between the intratesticular T concentration and the maintenance of spermatogenesis. T was administered to intact adult male rats via sustained release polydimethylsiloxane capsules in order to experimentally clamp T at well defined concentrations within the seminiferous tubules. Implantation of T-filled capsules of increasing sizes resulted in linear increases in T concentrations in serum, interstitial fluid, and seminiferous tubule fluid (STF). We examined the effect of step decreases in intratesticular T concentration on the numbers of advanced spermatogenic cells maintained by the testis over a 2-month period. Quantitatively complete spermatogenesis was maintained despite an 80% reduction in the STF T concentration (to approximately 13 ng/ml) from control values. The ability of the testis to maintain complete spermatogenesis was extremely sensitive to further decreases in STF T concentration. Thus, reduction of the STF T concentration from approximately 13 to 9 ng/ml resulted in a reduction in the number of advanced spermatids that were maintained in the testis by approximately 100 x 10(6). Reduction of the STF T concentration to approximately 4 ng/ml resulted in a further reduction in the number of advanced spermatids per testis by 100 x 10(6). Taken together, these data support the contention that there is far more T present within the seminiferous tubules of intact rat testes than is required to maintain quantitatively normal spermatogenesis and reveal for the first time that there is a dose-response relationship between the STF T concentration and the quantitative maintenance of advanced spermatogenic cells in the rat testis.

Animals↗
PubMed1989

Quantitative restoration of advanced spermatogenic cells in adult male rats made azoospermic by active immunization against luteinizing hormone or gonadotropin-releasing hormone.

The ability of testosterone to quantitatively restore spermatogenesis in rats made azoospermic by active immunization against LH or GnRH was examined. Sexually mature adult male rats (n = 15/group) were actively immunized against ovine LH or GnRH-human serum globulin conjugate, while control rats (n = 10) were injected with saline. After 10 weeks of immunization, five rats per group were euthanized. For each rat, trunk blood was collected for determination of LH, FSH, and testosterone by RIA; seminiferous tubule fluid (STF) was collected from one testis per rat, and testosterone concentration was measured by RIA; the number of advanced spermatids per testis was determined from the contralateral testis. The results obtained after 10 weeks of treatment were as follows. 1) Serum LH and FSH were undetectable by RIA in GnRH-immunized rats. 2) Serum testosterone was undetectable in both the LH- and GnRH-immunized groups. 3) The testosterone concentration in STF (STF-T) was reduced from the control value of about 64 ng/ml to about 2 ng/ml in the LH- and GnRH-immunized rats. 4) LH- and GnRH-immunized rats were azoospermic. After the initial 10-week treatment period, five rats in each of the LH- and GnRH-immunized groups received 24-cm testosterone-filled polydimethylsiloxane (PDS-T) capsules (3 x 8 cm long) sc. The remaining immunized rats (n = 5/group) received empty capsules. Two months later, all rats were euthanized. Testis weights, serum testosterone, and STF-T concentrations remained significantly reduced in LH- and GnRH-immunized rats that did not receive testosterone supplementation, and the rats remained azoospermic. STF-T concentrations rose significantly (P less than 0.05) in the LH- and GnRH-immunized rats that received PDS-T, but were still significantly less (by approximately 80%) than the concentration in intact controls. Nonetheless, implantation of PDS-T caused restoration of advanced spermatogenic cells in the testes of both LH- and GnRH-immunized rats to numbers that were not significantly different from the number in controls. These data indicate that 1) testosterone is capable of quantitatively restoring spermatogenesis in rats actively immunized against LH or GnRH, suggesting that FSH may not be required for the restoration of spermatogenesis in adult rats; and 2) quantitatively complete restoration of spermatogenesis can occur at STF-T concentrations that are significantly reduced compared to those in intact controls.

Animals↗
PubMed1987

The effects of proteolytic enzymes on in vitro ovulation in the rabbit.

The involvement of proteolytic enzymes in follicle rupture was assessed by use of the in vitro perfused rabbit ovary. Streptokinase (10 and 100 units/ml) induced ovulation in the absence of gonadotropin. Ovulation failed to occur in contralateral control ovaries. The time of ovulation in streptokinase- and human chorionic gonadotropin--treated ovaries was similar, but significantly more ova from streptokinase-treated ovaries were immature (p less than 0.001). Other ovaries were pretreated with trans-4-(aminomethyl)-cyclohexane-carboxylic acid, an inhibitor of the conversion of plasminogen to plasmin, and then perfused with human chorionic gonadotropin (50 IU). Ovulatory efficiency was significantly reduced by trans-4-(aminomethyl)-cyclohexane-carboxylic acid at 10 or 1 mmol/L (p less than 0.001), but ovum maturity was unaffected. Aprotinin (100 or 10 micrograms/ml), a potent inhibitor of plasmin, significantly inhibited human chorionic gonadotropin-induced ovulation (p less than 0.001) but did not affect oocyte maturation. Scanning electron microscopy of detergent-treated streptokinase-perfused ovaries revealed loosening and decomposition of collagen in the tunica albuginea. These results suggest proteolytic enzyme involvement in follicle rupture.

Animals↗
PubMed1987

Are ovarian steroids required for ovum maturation and fertilization? Effects of cyanoketone on the in vitro perfused rabbit ovary.

An isolated perfused rabbit ovary preparation was used to determine the effects of cyanoketone, a potent inhibitor of 3 beta-hydroxysteroid dehydrogenase, on ovulation, ovum maturation and fertilizability, and steroid production. In the first experiment, cyanoketone (10(-4) M) was added to the perfusate of one ovary. The contralateral control ovary was perfused with medium alone. Thirty minutes after the onset of perfusion, hCG (50 IU) was added to the perfusate of both ovaries. The ovulatory efficiency of ovaries treated with cyanoketone plus hCG (82.3 +/- 4.6%) was similar to that of ovaries treated with hCG alone (84.8 +/- 4.4%). No difference was observed in the degree of ovum maturity or degeneration between control and cyanoketone-treated ovaries. Progesterone and estradiol production were significantly reduced by cyanoketone treatment; concentrations in the perfusate of ovaries treated with cyanoketone were 9.7% and 8.0% of the control values, respectively, 2 h after exposure to hCG. The concentration of 17-hydroxypregnenolone was not affected by cyanoketone treatment. Exposure to cyanoketone resulted in a significant (P less than 0.005) reduction in the fertilizability of ova ovulated and fertilized in vitro. In the second experiment, the percentage of ova that showed evidence of normal fertilization was significantly (P less than 0.025) increased in ovaries perfused with cyanoketone plus estradiol (64.5%) compared to that in ovaries perfused with cyanoketone alone (32.4%). In the third experiment, the addition of progesterone to the perfusate did not affect fertilizability of ovulated ova in ovaries perfused with cyanoketone plus estradiol. These results suggest that the presence of estradiol in the ovarian steroid environment may be essential for fertilizability of ova, but not for the processes of ovulation or meiotic maturation.

3-Hydroxysteroid Dehydrogenases↗
PubMed1987

Estradiol reverses the limiting effects of clomiphene citrate on early embryonic development in the in vitro perfused rabbit ovary.

This study examined whether the addition of estradiol (E2) to the perfused rabbit ovary would reverse the deleterious effects of clomiphene citrate (CC) on early embryonic development. Ovaries were perfused with CC (10(-5) M) or CC + E2 (1 to 1000 ng/ml). Human chorionic gonadotropin (hCG, 50 IU) was added to the perfusate of each ovary. In vitro ovulated ova in cumulus were retrieved and inseminated in vitro. E2 significantly increased the percentage of ovulated ova achieving (1) the 2-cell stage at 36 hours, (2) the morula stage by 84 hours, and (3) the blastocyst stage at 132 hours. The percentage of inseminated ova showing evidence of degeneration was reduced in ovaries treated with E2. These data suggest that CC may exert an antiestrogenic effect on the intrafollicular oocyte, which interferes with postfertilization development.

Animals↗
PubMed1986

The effect of ovarian steroidogenesis on ovulation and fertilizability in the in vitro perfused rabbit ovary.

The effects of aminoglutethimide phosphate (AGP) on ovulation, ovum maturation, fertilizability, and steroid production were studied with the use of an isolated perfused rabbit ovary preparation. AGP (10(-3) or 10(-4) M) was added to the perfusate of one ovary. The contralateral control ovary was perfused in medium alone. Thirty minutes later human chorionic gonadotropin (hCG) (50 IU) was added to the perfusate of all ovaries. No difference was observed in time of ovulation or ovulatory efficiency between controls and AGP-treated ovaries. The degree of ovum maturity and degeneration was also comparable in the two groups. Progesterone and estradiol production were significantly reduced by AGP treatment. A second experiment examined fertilizability of ova ovulated in vitro after perfusion with 10(-3) M AGP. AGP significantly reduced the rate of normal fertilization as observed 12 h after insemination. The percentage of inseminated ova with evidence of degeneration was greater in ova from AGP-treated ovaries than in those from controls, however, this difference was not significant. The study indicates that AGP affects neither hCG-induced ovulation nor meiotic resumption; however, fertilizability of ova from ovaries treated with AGP is impaired. These data suggest that the intrafollicular steroid environment may participate in cytoplasmic maturation of ovulated ova.

Aminoglutethimide↗
PubMed1985

Microvasculature of preovulatory follicles: comparison of in situ and in vitro perfused rabbit ovaries following stimulation of ovulation.

Perifollicular vasculature undergoes significant morphologic changes as ovulation approaches. These vascular changes were observed in in vitro perfused and in situ rabbit ovaries by means of scanning electron microscopy of microcorrosion casts. Casts were made in in situ unstimulated ovaries, in situ ovaries stimulated with human chorionic gonadotropin, in vitro perfused unstimulated ovaries, and in vitro perfused ovaries after an ovulation-inducing dose of human chorionic gonadotropin, prostaglandin F2 alpha, histamine, or norepinephrine. Dilated vessels, extravasation of resin from weakened vessels, and filling defects at the apex of the follicle were observed in in situ ovaries 9 to 12 hours after stimulation and in in vitro perfused ovaries 4 to 6 hours after human chorionic gonadotropin. In vitro perfused ovaries stimulated with prostaglandin F2 alpha or histamine demonstrated dilated capillaries with extravasation of the resin and filling defects at the apex of large follicles. Norepinephrine-stimulated ovaries showed incomplete filling of vessels, although some large follicles showed extravasation of resin. The occurrence of dilated vessels, extravasation of resin, and filling defects is indicative of preovulatory vascular changes in both in situ and in vitro perfused ovaries, regardless of the ovulatory stimulus.

Animals↗
PubMed1985

Examination of the role of calcium in ovulation in the in vitro perfused rabbit ovary with use of ethyleneglycol-bis(beta-aminoethyl ether)-n,n'-tetraacetic acid and verapamil.

The in vitro perfused rabbit ovary preparation was used to examine the role of calcium in the ovulatory process. Two groups of rabbits were studied. In the first group, verapamil hydrochloride (10(-4) mol/L), a calcium channel blocker, was used together with human chorionic gonadotropin (50 IU) in the perfusate. Verapamil had no apparent effect on human chorionic gonadotropin-induced ovulation. Verapamil treatment, however, significantly reduced the percentage of ovulated ova that were mature (68.8%) in comparison to ovulated ova from human chorionic gonadotropin-treated control ovaries (95.0%). In a second experimental group, ethyleneglycol-bis(beta-aminoethyl ether)-n,n'-tetraacetic acid (2.0 mmol/L), a calcium ion chelator, was included in the perfusate with gonadotropin. The ethyleneglycol-bis(beta-aminoethyl ether)-n,n'-tetraacetic acid significantly reduced ovulatory efficiency (16.7% +/- 9.43%) in comparison to that of controls exposed to human chorionic gonadotropin alone (79.5% +/- 11.1%). In addition, ovulation occurred at an earlier time in ovaries perfused with ethyleneglycol-bis(beta-aminoethyl ether)-n,n'-tetraacetic acid; however, only four ovulations occurred in these ovaries. These four ovulated ova were immature, probably reflecting the early time of ovulation. Furthermore, both verapamil and ethyleneglycol-bis(beta-aminoethyl ether)-n,n'-tetraacetic acid blocked ovarian smooth muscle contractions during ovarian perfusion. These data provide additional support for the concept that calcium dynamics influence the processes of ovulation and ovum maturation. Furthermore ovarian smooth muscle contractions do not appear to be essential for ovulation in this model.

Animals↗
PubMed1985

Direct ovarian effect of clomiphene citrate in the rabbit.

The effects of clomiphene citrate (CC) on ovulation and ovum maturation were studied using the isolated perfused rabbit ovary. CC (10(-5) M) added to the perfusate with human chorionic gonadotropin (50 IU) did not affect ovulatory efficiency, ovulation time, oocyte maturation, or degeneration of ovulated ova and follicular oocytes. During perfusion without human chorionic gonadotropin, the percentage of follicular oocytes with germinal vesicle breakdown was significantly increased in response to CC (10(-5) M or 10(-7) M); a greater percentage of follicular oocytes was degenerated. Estradiol (100 ng/ml) added to the perfusate reversed the effect of CC on degeneration of follicular oocytes. Of follicular oocytes from ovaries perfused with CC, 79.3% were degenerated; in contrast, 25% were degenerated in ovaries treated with CC plus estradiol. These data suggest that CC has a direct ovarian effect and that ovum degeneration associated with CC may be related to an antiestrogenic action.

Animals↗
PubMed1985

The relationship between prostaglandins and histamine in the ovulatory process as determined with the in vitro perfused rabbit ovary.

The process of follicle rupture has been described as an inflammatory reaction in which prostaglandins (PGs) and/or histamine may be involved. With an in vitro perfused rabbit ovary preparation, experiments were carried out for determination of whether a relationship exists among PGs, histamine, and ovulation. PGF2 alpha alone was capable of inducing ovulation when added to the perfusion fluid at 1, 10, and 100 ng/ ml. Effectiveness in achieving ovulation varied directly with the dosage; however, the ovulatory efficiency of PGF2 alpha-treated ovaries was lower than that of ovaries exposed to human chorionic gonadotropin (hCG, 100 IU). PGF2 alpha-induced ovulation could not be blocked by the H2 receptor antagonist, cimetidine. The PG synthesis inhibitor, indomethacin, did not prevent histamine-induced ovulation. Ovulation induced by hCG was partially blocked by the administration of indomethacin; however, the concomitant administration of cimetidine was not associated with further reduction in ovulation. In all but one experimental group, the majority of ovulated ova did not progress beyond the intact germinal vesicle stage unless the ovaries had been exposed to hCG. On the basis of these experiments, PGs and histamine do not appear to be interdependent in their effects on the ovulatory process in vitro.

Animals↗
PubMed1984

Ultrastructure of ovarian follicles in in vitro perfused rabbit ovaries: response to human chorionic gonadotropin and comparison with in vivo observations.

Ovulation may be achieved and studied in an isolated perfused rabbit ovary upon inclusion of human chorionic gonadotropin (hCG) in the perfusion fluid. The ultrastructural features of the rabbit ovarian follicle prior to ovulation in vitro were compared with those in vivo. The perifollicular vasculature was also examined in in vitro perfused rabbit ovaries during the preovulatory interval. Granulosa cells of the preovulatory follicle share many ultrastructural features in vivo and in vitro; however, only small amounts of smooth endoplasmic reticulum (sER) were observed in granulosa cells in vitro after hCG. Ovulation after hCG in the in vitro preparation tends to occur earlier (6 hours) than in vivo (12 hours). Thus, there may be insufficient time and/or gonadotropin exposure to permit full functional development of granulosa cells, as reflected by reduced amounts of sER. Degradation of collagen fibrils was less prominent in the theca externa and tunica albuginea in vitro than in in vivo. Perifollicular capillaries became dilated after hCG, but interendothelial gaps were not observed. Disappearance of surface epithelium in the apex of follicles was similar in vitro and in vivo.

Animals↗