Characterization of the fertility of Kit haplodeficient male mice.

The role of the proto-oncogene Kit expression during gonadal development, then in differentiated spermatogonia has been thoroughly established. The present study was designed to investigate the consequences of a partial defect in Kit gene expression on sperm fertilizing ability, using Kit haplodeficient mice (kitW-lacZ/+). Same inbred mice (kit+/+) were used as controls. Epididymal sperm characteristics and in vivo fertility were assessed, then in vitro-fertilization experiments were carried out for mice of both genotypes. Epididymal sperm count was drastically reduced, and sperm motility was also decreased in kitW-lacZ/+ compared with kit+/+ males. Both in vivo or in vitro fertility were greatly reduced in kitW-lacZ/+ compared with kit+/+ males. By contrast, the fertility of kitW-lacZ/+ females was apparently unaffected. Additionally, a higher number of spermatozoa with undetected acrosomal contents was revealed by fluorescein isothiocyanate-labelled Pisum sativum agglutinin acrosomal staining after epididymal sperm retrieval in kitW-lacZ/+ mice, whereas no difference was observed after induction of acrosomal reaction in mice of either genotype. Ultra-structural data confirmed the higher frequency of abnormal acrosome in spermatozoa of kitW-lacZ/+ mice. Thus, sperm production is impaired in Kit haplodeficient mice both on a quantitative and a qualitative basis. Finally, we show that one single copy of Kit gene is not sufficient to maintain genuine fertility in male mice.

Anti-Müllerian hormone (AMH) secretion in prepubertal and adult rams.

The aim of the present analysis was to determine whether anti-Müllerian hormone concentrations in prepubertal plasma or adult rete testis fluid are related to the number or function of Sertoli cells in rams or to the presence of the FecB Booroola gene. Twenty rams from two Booroola crosses, differing in their testicular masses were analysed; in each cross, half of the animals were heterozygous carriers of the FecB gene. The data from rams, during prepuberty and at adulthood during the non-sexual season, were analysed by two-way ANOVA and residual correlations. In 4-week-old intact male lambs, the mean anti-Müllerian hormone plasma concentration was 15 ng ml-1, irrespective of cross, genotype or eCG stimulation; it was significantly negatively correlated with FSH (r = -0.51; P = 0.02; n = 19). In adults, anti-Müllerian hormone was not detectable in plasma and was 0.5 ng ml-1 in rete testis fluid, irrespective of cross or genotype. The total number of Sertoli cells per testis was not related to anti-Müllerian hormone concentration in lamb prepubertal plasma or in adult rete testis fluid. The concentration of anti-Müllerian hormone in adult rete testis fluid was significantly and negatively correlated with the daily production of leptotene primary spermatocytes per testis (r = -0.56; P = 0.02; n = 16). The mean oestrogen concentration in the adult testicular vein was 2 pg ml-1 and was correlated negatively with the rete testis fluid concentration of anti-Müllerian hormone (r = -0.60; P = 0.02; n = 15) and correlated positively with the daily production of leptotene primary spermatocytes per testis (r = 0.53; P < 0.05; n = 19). In conclusion, anti-Müllerian hormone secretion was not correlated with the total numbers of Sertoli cells per testis and cannot be used as a predictor of the number of Sertoli cells. Anti-Müllerian hormone secretions were not affected by the presence of FecB gene. However, anti-Müllerian hormone secretion could be considered to be inversely related to the daily production of primary spermatocytes by the testis.

Proliferation and differentiation of porcine inner cell mass and epiblast in vitro.

The proliferation rate and differentiation state were investigated in porcine inner cell masses (ICMs) and epiblasts in vitro. ICMs isolated from early blastocysts (Day 7 of pregnancy) and epiblasts isolated from preelongated blastocysts (Day 11 of pregnancy) were cultured for up to 5 days in the presence of human leukemia inhibitory factor (hLIF) (1000 U/ml). The proliferation rate was evaluated by determination of the percentage of cells in S-phase. The differentiation state was determined by studying the expression of the stage-specific embryonic antigen-1 (SSEA-1), a marker for undifferentiated murine embryonic stem (ES) cells, and the expression of laminin and cytokeratins 8/18, markers of ES cell differentiation. The staining pattern showed that freshly collected Day 11 epiblasts appeared undifferentiated but rapidly lost this characteristic in vitro. A decrease in the proliferation rate was also observed during culture. This decrease was reduced in the presence of high concentrations of hLIF (optimal concentrations: 5000 U/ml). Conversely, treatment of Day 11 epiblast cells with retinoic acid, an agent known to induce differentiation in murine ES cells, caused a dramatic decrease in the proliferation rate in vitro. In contrast to Day 11 epiblasts, Day 7 ICMs expressed SSEA-1 in vitro and showed a higher proliferation rate (p < 0.01). However, their proliferation rate also decreased during culture and following trypsinization. These results indicate that the undifferentiated characteristics of Day 7 ICMs are more likely to be maintained in vitro than are those of Day 11 epiblasts, which are rapidly committed into early differentiation.

Induced differentiation of ovine foetal gonocytes after grafting in the scrotum of nude mice.

This work was designed to elucidate, in foetal ovine testis, whether the reason why gonocytes do not differentiate into spermatogonia and do not initiate spermatogenesis is due to inadequate foetal environment (temperature and/or hormonal balance) or if somatic testicular cell proliferation is a prerequisite for initiation of male meiosis. The development and differentiation of gonocytes were analysed by grafting 60-day-old foetal ovine tests into the scrotum of immunotolerant adult Nude mice. Forty days after grafting, nine of the ten grafted testes had survived but had not increased in weight as compared to 60-day-old tests. Moreover, only one third of the graft was occupied by testicular tissue, in which the relative proportions of intertubular tissue and sex cords were not altered when compared with those of normal foetal testes. The remainder of the graft was occupied by teratoma. The total number of Leydig (-80%) cells, Sertoli (-66%) cells, gonocytes (-90%) and the total length of sex cords (-63%) per grafted testis were always significantly reduced (P < 0.02), whereas the sex cords were significantly increased in diameter (+36%; P = 0.02) as compared to those of non-grafted 60-day-old foetuses. However, in seven out of the nine testes, type A spermatogonia were obtained and in two of the seven a few type B or leptotene primary spermatocytes could be observed. The grafting of foetal testis in an adult scrotum induces differentiation of gonocytes into spermatogonia, independently of proliferation of Sertoli and Leydig cells.

Effects of the Booroola gene FecBB on somatic and germ cells of the fetal testis.

The present study was conducted to compare in homozygous FecBBFecBB(BB) Booroola and ++ male fetuses, the body and the testicular growths and the tissular and cellular compositions of the testis between 60 and 140 days of gestation. To eliminate differences in growth due to uterine environment, single embryos have been transferred in recipient Mérinos d' Arles ewes. At 60 and 100 days of gestation, the body masses of BB fetuses were significantly lower than those of ++ foetuses (11 and 13%; P = 0.05); but their testis masses of their total contents of somatic (Leydig or Sertoli) cells did not differ significantly whatever the fetal age. At 100 and 140 days of gestation, testis and body masses were significantly correlated without difference between BB and ++ genotypes. In conclusion, the presence or absence of homozygous gene FecBB does not induce significant differences in somatic or germ cell composition of the testis between 60 and 140 days of gestation.

Evidence for germ cell control of Sertoli cell function in three models of germ cell depletion in adult rat.

In order to clarify the role of germ cells in the regulation of Sertoli cell secretions, three experimental models of germ cell depletion were used: hypodactyl rat mutation (testis weight [TW]: 55% less than controls), in utero busulfan treatment (TW: 88% less than controls), and neonatal experimental cryptorchidism (TW: 72% less than controls). The aim of this work was to compare the numbers of Leydig and Sertoli cells and the production of germ cells in each experimental model to the in vitro secretions of Leydig and Sertoli cells in conditioned media and to the hormonal serum profiles of the same animal in vivo. In the three models, serum levels of hypophyseal and testosterone hormones were significantly increased and decreased, respectively. In the absence of germ cells, the total length of seminiferous tubules, the total numbers of Sertoli and Leydig cells, and the daily production of germ cells were significantly diminished. The addition of both control and damaged seminiferous tubule culture media (STM: media conditioned by 10 cm of seminiferous tubules) to 10(6) control or damaged Leydig cells led to a further increase of testosterone production after ovine LH stimulation. However, expressed per Sertoli cell, testosterone production by control Leydig cells was reduced by addition of damaged STM as compared to addition of control STM, and similarly, the addition of control STM to damaged Leydig cells enhanced testosterone production more than did the addition of damaged STM. Secretions of transferrin per Sertoli cell in STM were reduced as compared to controls by the absence of germ cells but to a lesser extent than was production of spermatocytes and of spermatids. In conclusion, secretions by Sertoli cells of the paracrine factor involved in the control of testosterone production by Leydig cells and of transferrin are modified by germ cells.

Evolution of somatic and germ cell populations after busulfan treatment in utero or neonatal cryptorchidism in the rat.

In order to elucidate the respective effects of depletion of germ cells and of increase in testicular temperature, rats of the same Wistar strain were rendered experimentally bicryptorchid or sterilized by a busulfan injection in utero and compared to control animals. In both models, germ cells were depleted but numeric evolution and functions of somatic cells differed. The aim of that work was to compare the numeric evolutions of testicular somatic and germ cells to their respective functions in each model before puberty and in adult rats of the same strain. Serum concentrations of FSH, LH and testosterone were compared at 20, 40 and 110 days of age. Histological analyses of Sertoli and germ cells in the seminiferous tubules and of Leydig cells in the intertubular tissue were performed before puberty and at adulthood. Testosterone serum concentrations were depleted in both models starting at 40 days of age and more in busulfan-treated rats. Both FSH and LH levels were increased from 20 days onwards in experimental rats. Additional cryptorchidism in busulfan-treated rats depressed the serum testosterone concentration. At 17 days of age, the cryptorchidism do not modify somatic or germ cell populations while busulfan treatment has induced a decrease of both these populations. Conversely, the cross sectional area of the somatic testicular cells was not affected whatever the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogenesis of somatic and germ cells in sheep fetal testis.

Testicular development of sheep fetuses was studied between day 42 of gestation and birth. Testis mass and the total number of testicular cells increased curvilinearly with fetal age and a positive linear relationship was established between the logarithmic values of age and testis mass, sex cord total length, total number of Sertoli cells, germ cells and Leydig cells per testis. The mean number of gonocytes per unit length of sex cord, the Sertoli cell nuclear cross-sectional area and the Leydig cell cross-sectional area decreased linearly with age between day 42 of gestation and birth. Hypophysectomy and hemicastration were performed to study the regulation of testicular cell divisions during fetal life and to determine whether they were under pituitary control and whether a feedback mechanism was present. Hypophysectomy at day 100 or 110 of gestation nonsignificantly decreased (0.05 < P < 0.01) the testis mass, total length of sex cords and total number of Sertoli cells and significantly decreased (P < 0.05) the cross-sectional area of Leydig cells and nuclei of Sertoli cells. Sex cord diameter and total number of gonocytes were unaltered. Hemicastration at day 110 of gestation significantly increased (P < 0.05) the total number of Leydig cells per testis without changing any other testicular parameter. In male sheep fetuses, the proliferation of testicular somatic and germ cells occurs throughout testicular fetal growth at a higher rate before day 100 of gestation than later, but without any differentiation. Mitotic divisions of Sertoli cells are more numerous before birth than afterwards. Before birth, the proliferation of gonocytes is not under pituitary control.

Effect of short photoperiodic cycles on male genital tract and testicular parameters in male goats (Capra hircus).

This study was performed in adult male goats in which seasonal variations were abolished by rapid alternations of long days and short days. These treatments have been shown previously to prevent seasonal changes in the hypothalamo-pituitary axis and to maintain testis weight and sperm production at a high level. The experimental groups were exposed for 3 years to an alternation of either a 1 month short (16 h dark; 8 h light) and 1 month long (16 L; 8 D) photoperiod (2 month cycle; n = 5) or of a 2 month short and 2 month long photoperiod (4 month cycle; n = 4). The control groups were maintained in natural photoperiodic conditions (45 degrees N) and goats were slaughtered in the non-breeding season (end of April RS; n = 5) at the same period as light-treated bucks, or in the breeding season (end of September BS; n = 6). The total weight of the testes, the length and mean diameter of the seminiferous tubules of light-treated goats were similar to those in the breeding season, and higher than those in the non-breeding season. The total number of A0 spermatogonia was increased by light treatments as compared to control goats in the breeding and non-breeding season. The daily production of A1 spermatogonia, leptonene primary spermatocytes and round spermatids in light-treated goats was maintained at the peak breeding season level. The intra-testicular concentration of testosterone, total volumes of intertubular tissue and of Leydig cells, and the number of Leydig cells per testis did not differ between groups. Although the mean cross-sectional area of Leydig cells in light-treated goats was similar to this area in non-breeding season goats, it was significantly lower than that of breeding season goats. In conclusion, the rapid alternation of short and long days allowed an increase in all the germ cells from the A0 spermatogonia onwards, which was responsible for the maintenance of high spermatogenetic activity of light-treated goats.

Effects of a single brief period of moderate heating of the testes on seminiferous tubules in hypophysectomized rams treated with pituitary extract.

An experiment was conducted to examine the appearance of the seminiferous tubule 20 days after a single exposure of the testes of rams to a scrotal temperature of about 42 degrees C for 45 min. Ten of the animals were surgically hypophysectomized and five were simultaneously heated; these rams were treated twice a day with ovine pituitary extract to avoid modifications in the negative feedback from the testes to the pituitary and consequent changes in gonadotrophin secretion. Six intact rams (three heated and three unheated) were also studied. The pituitary extract significantly increased the testis weight and spermatogonial multiplications from A1 spermatogonia onwards. Twenty days after the heat treatment, testis weight was significantly reduced by heating; both tubular and intertubular tissues were affected. The total length of seminiferous tubules per testis was not modified, whereas the mean seminiferous tubule diameter was significantly reduced after heating. The total number of Sertoli cells per testis was not significantly modified, while their mean cross-sectional nuclear area was significantly reduced by heat treatment. A decrease in the number of all germ cells except A0 spermatogonia, from A1 spermatogonia onwards, was observed. The number of round spermatids decreased by 95 and 90%, slightly more than the diplotene primary spermatocytes (76 and 77%) and elongated spermatids (79 and 85%) in hypophysectomized pituitary extract-treated and intact rams, respectively. Round and elongated spermatids would be derived from germ cells that were respectively leptotene and young pachytene primary spermatocytes at the time of heating, whereas diplotene primary spermatocytes would have been type B spermatogonia.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro culture of embryonic disc cells from porcine blastocysts.

The aim of the present study was to define the conditions of preparation and in vitro culture of embryonic discs allowing proliferation of ES-like cells. G5-6 porcine blastocysts (G0 = day of AI) were cultured in toto; in G10-11 blastocysts, trophectoderm and primitive endoderm were microsurgically removed from embryonic discs (ED) which were cultured either on plastic or on a feeder layer. Feeder cells were foetal G30 porcine fibroblasts which had been previously irradiated. Culture medium was DMEM supplemented with 0.1 mM beta-mercaptoethanol, 5% foetal calf serum, 5% Ultroser G and 10(3) IU LIF; cultures were performed at 38 degrees C. Colonies were reseeded weekly. Few embryonic discs from G5-6 and no elongating blastocysts gave rise to ES-like cells. At least 50% G10-11 ED attached and developed multilayered colonies (100 cells) of small ovoid ES-like cells. Colonies from 4 sows were maintained in culture for at least 8 wk. Addition of PDGF, insulin or both, induced a transitory stimulation of growth in G6 or G10-11 ED; TGF beta did not modify growth of G6 ICM. Uterine G10-11 flushing medium or retinol induced differentiation of ES-like cells. These cells introduced in nude mice induced teratoma.

[Pathogenic effects of Trypanosoma congolense on the testis of Baoulé bulls: quantitative and morphometric histology]. / Effets pathogènes de Trypanosoma congolense sur le testicule des taurins Baoulé: histologie quantitative et morphométrique.

The effect of Trypanosoma congolense on testis was studied in 53 trypano-resistant "Baoulé" bulls by quantitative histology and morphometry. The daily spermatozoa production per testis of control groups (n = 45) was 382 +/- 334 x 10(6) (m +/- sd) and the epididymis contained 0.6 +/- 1 x 10(9) spermatozoa in the caput, 0.3 +/- 0.3 x 10(9) in the corpus and 1.2 +/- 1.8 x 10(9) in the cauda. The infected bulls (n = 8) showed no significant difference (P > 0.05) when compared to the control despite their average low value. The morphometric analysis during infection revealed a significant (P < 0.05) decrease (32%) of total Leydig cell volume per testis, 4.4 +/- 0.9 cm3 for the control (n = 5) and 3.0 +/- 0.8 cm3 for infected bulls (n = 8). The number of round spermatids per Sertoli cell and the daily round spermatid production (DRSP) per testis were also significantly reduced in infected bulls when compared to controls (P < 0.05), 5.2 +/- 0.7 and 2.8 +/- 2 for round spermatid per Sertoli cell and 6.1 +/- 2.0 and 3.1 +/- 1.9 x 10(8) for DRSP. These observations indicate that Trypanosoma congolense infection alters the interstitial tissue and meotic divisions of germinal cells leading to low daily round spermatid production per gram of testis in "Baoulé" bulls.

Germ cell-Sertoli cell interactions and production of testosterone by purified Leydig cells from mature rat.

The addition of seminiferous tubule (ST) culture medium (STM) prepared from testes of either busulfan-treated (Bus) or cryptorchid (Cryp) or genetically sterile (hd) rats, to Percoll purified Leydig cells leads to a further increase of LH-stimulated testosterone (T) output (26, 43 and 14%, respectively). Taking into account that the Sertoli cell number per cm of ST is 2.6, 1.8 and 1.4-fold greater in Bus, Cryp and hd rats than in controls, the above STM effects on T output, expressed per 10(6) Sertoli cells are in fact lower (63, 44 and 43%, respectively) that those of control STM. Similar results have been obtained for the STM transferrin levels which are decreased, 74, 67 and 45%, respectively in Bus, Cryp and hd animals. So, it is likely that the Sertoli cell secretion of both the paracrine factor involved on Leydig cell T production and the transferrin is influenced mainly by spermatids and to a lesser extent by spermatocytes of mature rat testis.

Effect of a 2-month light cycle regimen on testicular parameters of adult Ile-de-France rams.

This experiment was conducted in Ile-de-France adult rams to examine the target point of a 2-month light cycle regimen on seminiferous tubule functions, on intertubular compartment and on Leydig cell parameters. Eight rams were subjected to a 2-month light cycle regimen and were compared to sexually active or inactive rams. In light-treated rams, testis weight was maintained equal or was higher than that of sexually active rams. Both tubular and intertubular tissues were found significantly higher in light-treated than in sexually active rams. The mean ratio of basement membrane area of the seminiferous tubules per Sertoli cells and the daily productions of A1 spermatogonia and of leptotene primary spermatocytes were significantly increased in light-treated rams as compared with sexually active or inactive rams. Meanwhile, the dairy productions of diplotene primary spermatocytes, of round spermatids, of spermatozoa and of the rete testis fluid were not significantly increased in light-treated as compared with sexually active rams but significantly greater than those of sexually inactive rams. Total volume, total numbers, and individual volumes of Leydig cells were at least equal or higher in light-treated than in sexually active rams.

The form and function of the Leydig cells in hypophysectomized rams treated with pituitary extract when spermatogenesis is disrupted by heating the testes.

The morphology and in-vivo function of the Leydig cells were studied in rams when spermatogenesis had been disrupted by a single exposure of the testes 20 days earlier to a temperature of about 42 degrees C for 45 min. To avoid complications due to changed negative feedback from the testes to the pituitary with consequent changes in the degree of gonadotrophic stimulation, ten of the animals (five heated and five unheated) were surgically hypophysectomized when the testes were heated and then treated twice daily with pituitary extract. Six intact rams (three heated and three unheated) were also studied. The heat-affected testes were about half the size of the unheated testes, and blood plasma flow was closely related to testis weight. There were no differences in the testosterone concentrations in spermatic venous blood, testicular lymph or rete testis fluid, or in oestradiol in spermatic venous plasma from heated or unheated testes. Consequently, testosterone secretion by the heat-affected testes was markedly reduced, and the concentrations in jugular blood were also lower in the heat-affected rams than in controls. The volume of the interstitial tissue was less in absolute terms in the heat-affected rams, but it made up a greater fraction of the testes. The absolute volume of the blood plus lymph vessels, and their fraction of the interstitial tissue were lower in the heat-affected testes, although there was no effect on their volume as a fraction of the whole testis. The heat-affected testes of the hormone-treated rams had fewer Leydig cells, but each cell was larger; no equivalent difference was found in the intact rams. However, the dose of pituitary extract chosen was somewhat excessive, as there were higher than normal concentrations of FSH, LH and testosterone in jugular blood plasma, of testosterone and oestradiol in testicular venous blood plasma and of testosterone in rete testis fluid in the hormone-treated hypophysectomized rams. The testes of the unheated hypophysectomized rams increased in size by about 20% during treatment with pituitary extract, although testicular blood plasma flow was lower per unit weight of testis. The absolute volume of each Leydig cell and the total volume in absolute terms and as a fraction of the interstitial tissue was greater in the hormone-treated than in the untreated rams, but not the volume as a fraction of the whole testis. The total number of Leydig cells was higher in the hormone-treated unheated rams than in all the other rams taken together.(ABSTRACT TRUNCATED AT 400 WORDS)

Age-related changes in the function of the pituitary-gonadal axis in a sterile male rat mutant (hd/hd).

Testicular growth is depressed in the genetically sterile male rat (hd/hd) relative to its LE phenotype littermates (by 50% and 73% at 27 and 90 days of age, respectively). Within the hd/hd testis, both the tubular and seminiferous tubule tissues are affected by the mutation. In addition, there is significantly less germ cell production from the primary spermatocyte stage of spermatogenesis onwards and the total number of Sertoli cells observed is less. In the intertubular tissue, the total volume and the total number of Leydig cells per testis is significantly less, but the mean volume of an average Leydig cell is not modified. The serum gonadotropin levels are higher in the hd/hd rat, whereas from 40 days of age onwards the level of testosterone is lower. The FSH and LH binding affinity constants are unchanged by the mutation; however, the total number of FSH binding sites per 10(6) Sertoli cells is lower while that of LH per 10(6) Leydig cells is greater. Indeed, it is likely that the lesser concentration of serum testosterone in the hd/hd rat is a result of a smaller number of Leydig cells since their individual function is not modified. The testicular androgen binding protein (ABP) content and the ABP output towards the epididymis are lower as a consequence of both a lesser number and an altered function of the Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for LH-inhibiting activity in ovine peripheral and testicular blood.

Intracellular cyclic AMP and testosterone productions by purified mature rat Leydig cells were stimulated by oLH (25 micrograms/l) 18- and 12-fold, respectively, after a 5-h incubation period. The replacement of the incubation medium by charcoal-treated testicular venous plasma (40%, v/v) from adult rams in the breeding season induced an inhibition of cyclic AMP and testosterone productions (82 and 66%, respectively, of oLH-stimulated values). Testicular arterial plasma is less effective than testicular venous plasma, even when it originates from non-breeding season rams; in that case, testicular venous and arterial plasma strongly inhibit testosterone productions (84 and 67%, respectively of oLH-stimulated values), which probably indicates that the inhibitory activity is higher in the non-breeding season. The addition of peripheral plasma leads to a testosterone production equal to 35 and 65% of the oLH-stimulated values, respectively, for ram blood collected in non-breeding and breeding seasons. The same concentration of ovine testicular lymph or rete testis fluid is without significant effect on cyclic AMP production; however, testosterone is slightly decreased by lymph but enhanced by rete testis fluid. Increasing amounts of venous or arterial testicular blood induce a dose-related decrease of the specific binding of labelled hCG in both rat and ram testicular membranes. This inhibiting factor is present in peripheral and testicular blood of either control or hypophysectomized or castrated rams, is a protein in nature, heat-sensitive, and has an apparent molecular weight higher than 10,000 daltons.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparisons of endocrinological and testis parameters in 18-month-old Ile de France and Romanov rams.

Endocrinological and testis parameters of adult 18-month-old Ile de France (IF) and Romanov (Ro) rams were compared during sexual season. Testis weights, total volumes of intertubular tissue, and of blood and lymph vessels, total seminiferous tubule length, rete testis flow rate and daily production of germ cells were significantly higher in IF than in Ro rams. These variations originated from differences in Sertoli cell numbers, which were established before puberty. When daily productions of germ cells, of ABP or of RTF were expressed per Sertoli cell, they were higher in Ro than in IF rams. Quality of spermatids, as measured by their cellular size prior to elongation, was lower in Ro than in IF. The number of FSH-binding sites per Sertoli did not differ between the two breeds but FSH plasma levels were higher in Ro than in IF rams. Total numbers of Leydig cells per testis, their individual size or their LH-binding capacity did not differ significantly between the two breeds. However, the ratio of mean testosterone upon mean LH plasma levels were greater in Ro than in IF rams while both breeds had identical LH mean plasma levels.

[Demonstration of LH inhibitor(s) in sheep and human sera]. / Mise en évidence d'un (ou des) inhibiteur(s) de LH dans les sérums ovin et humain.

In mature rat Leydig cells, the testosterone output (24 ng/10(6) Leydig cells/4hrs.) is increased 10 fold by LH; the addition of serum from either control or castrated or hypophysectomized rams inhibits (60%) the LH-stimulated testosterone production. Similarly, the incubation of immature rat Leydig cells with sera from hypophysectomized patients leads to a diminution (70 and 30% respectively) of both basal (0.98 ng) and LH stimulated (3.44 ng) testosterone biosynthesis. These data suggest the existence of an LH inhibitor (or inhibitors) in blood from ram and human; in addition, this substance is not only of testicular origin and is not an LH-related molecule.