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.

[Apoptosis in the male gonad]. / L'apoptose dans la gonade mâle.

Self-destruction of a cell following an internal or exogenous stimulus was a major concept which emerged in the early seventies. Such a phenomena is now reported to influence both embryonic development and tissue growth or renewing. Tumor growth as well as treatment may depend on apoptosis. This phenomena is identified using morphological as well as biochemical criteria. Spermatogenesis is a target for apoptosis which participate in the regulation of sperm production. Endocrine control of apoptosis in the seminiferous tubule was thoroughly studied, and some mechanistical studies dealing with oncogenes involved in apoptosis control have been done. Apoptosis is a key phenomenon in the control of sperm production.

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.

Localization and quantification of melatonin receptors in the diencephalon and posterior telencephalon of the sheep brain.

In an attempt to better understand the mechanisms by which melatonin controls neuroendocrine activity, we tried to define with accuracy the brain areas where the density of melatonin receptors is the highest in sheep and to establish their characteristics. The specific labelling of 125I-melatonin was first revealed by autoradiography on brain sections of the posterior telencephalon and diencephalon in three ewes. The extent and position of the five structures where the binding was found to be the highest (i.e., the pars verticalis and pars horizontalis of the nucleus tractus diagonalis, the septal area, the bed nucleus of the stria terminalis, and the ventromedial hypothalamic area) were then accurately defined by image analysis. In comparison to the landmarks given by image analysis, photographs of coronal sections of another ewe permitted the accurate definition of the limits of the structures to be punched in a second step. In six ewes, each of the five structures previously identified were punched from frozen coronal sections and binding of 125I-melatonin to membrane preparations was studied individually by Scatchard analysis. The correlation coefficient between the B/F ratio and binding (B) was in the range of 0.96-0.98, indicating that a precise quantification was possible in these different structures. The Bmax was the highest in the bed nucleus of the stria terminalis, the septal area, and the ventromedial hypothalamic area (1.38, 1.25, and 0.95 fmol/mg protein, respectively). All Kd values were less than 10 pM and the Hill coefficient was close to 1, indicating the presence of a single class of receptor to 125I-melatonin. These results indicate the reliability of a method used to measure with accuracy low concentrations of melatonin receptors in brain structures. In addition, the ventromedial hypothalamic area was found to be rich in melatonin receptors. This region is known to be involved in the central gonadotrope control in sheep.

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.

Effects of an LH-RH agonist on reproductive responses and endocrinological parameters in landais ganders.

Semen quantitative (sperm production) and qualitative parameters (percentage of live and normal spermatozoa, sperm motility, egg fertility and hatchability), as well as hormonal parameters (LH and testosterone plasma concentrations) were compared for landais ganders, which were treated or not, with an LH-RH agonist prior to being sexually active. Treatment with the LH-RH agonist at this physiological stage delayed the onset of sperm production in some of the treated males. Although, comparable data were obtained during the first half of the reproductive period, treatment with the LH-RH agonist maintained sperm output at higher levels during its second half. Although the percentage of normal and live spermatozoa, sperm motility and true hatchability did not differ, the LH-RH agonist treatment had a positive effect on gosling production because of the higher fertility of the treated birds during the second part of the reproductive period. Treatment induced a large short-term decrease in testosterone levels followed by a rebound, leading to higher levels during the second half of the reproductive period. We conclude that treatment of ganders with an LH-RH agonist partially prevented the naturally occurring decline in sperm production and induced an increase in the rate of fertility rates during the second half of the productive period.

Changes in LHbeta-gene and FSHbeta-gene expression in the ram pars tuberalis according to season and castration.

Luteinizing hormone beta (LHbeta) and follicle stimulating hormone beta (FSHbeta) subunits and their mRNAs were studied in the ram pars tuberalis following different seasonal (winter vs summer) and experimental (intact vs castrated animals) conditions. Hormone-containing cells were identified by immunohistochemistry, using homologous double-stranded 35S-cDNAs. The labelling was quantified by image analysis. Immunohistochemical staining showed that cells containing LHbeta and FSHbeta were localized mainly in the ventral part of the pars tuberalis but that, in the summer, additional LHbeta containing cells were present in the dorsal part in intact rams. On the other hand, LHbeta-mRNA labelling was found in the whole pars tuberalis in wethers but only in the ventral part in intact rams. The magnitude of LHbeta-mRNA labelling was significantly greater in summer than in winter rams, and in castrated than in intact animals (P<0.001). However, the number of labelled cells was found to be the greatest in the winter (P<0.001) and was not affected by castration. FSHbeta-mRNA expression was similar to that of LHbeta-mRNA except that the level and extent were considerably lower. Thus, our results show an increase in the magnitude of gonadotropin beta subunit-mRNA in the summer and following castration; this increase appears to involve the entire pars tuberalis.

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.

Induced moulting in cockerels: effects on sperm production, plasma concentrations of luteinising hormone, testosterone and thyroxine, and on pituitary sensitivity to luteinising hormone-releasing hormone.

1. The ability of a moult-inducing procedure to restore high levels of sperm production was assessed, in two experiments, using cockerels with reduced sperm production. The moulting procedure consisted of a period of food and light restriction for 6 weeks. The moulted birds were compared with control birds for 20 weeks. 2. Moult induction resulted in decreased daily sperm output (DSO) and plasma testosterone concentration, from weeks 3 to 7. In the first experiment, plasma luteinising hormone (LH) concentration in moulted birds was reduced on week 5. 3. No change in pituitary sensitivity to chicken luteinising hormone-releasing hormone-I (cLHRH-I) was detected at week 3 in moulted cockerels. In moulted birds, a transient increase in plasma thyroxine concentration was detected. 4. After the end of moult induction, testosterone concentrations increased, plasma LH showed a rebound at week 7 and the pituitary sensitivity to LHRH was increased at week 9. 5. This increased activity of the pituitary-testicular axis resulted for a short time in an increase in DSO of moulted birds compared with that of controls. Although amelioration was moderate, this result indicates the possibility of improving sperm production in the cockerel by using an induced moulting procedure.

Effect of thyroxine on testicular function, circulating luteinising hormone and pituitary sensitivity to luteinising hormone-releasing hormone in the cockerel (Gallus domesticus).

1. The effect of thyroxine (T4) on reproductive function in the adult cockerel was followed for 11 weeks. Broiler cockerels aged 96 weeks were fed on diets containing either 0, 2 or 5 mg T4/kg for 4 weeks. 2. Daily sperm output (DSO) was significantly reduced (P < 0.01) in the T4-treated groups compared with that of controls at weeks 5 and 7. In the group given 5 mg T4/kg, plasma testosterone concentration was significantly reduced (P < 0.01) compared with that in controls during the T4 treatment, in spite of the fact that there was a decrease in concentration in both control and experimental birds. Plasma luteinising hormone (LH) concentration was significantly decreased (P < 0.05) in both of the groups given T4 treatments after 3 weeks. 3. Plasma testosterone concentrations and DSO had returned to control values at weeks 5 and 11 respectively, while plasma LH showed a transient but significant (P < 0.001) rebound after removal of thyroxine from the food. 4. In contrast to other variables, the pituitary responsivity to cLHRH-I injections, was not decreased during the feeding of the T4 diet but was, on the contrary, significantly increased (P < 0.05) during treatment with 5 mg T4/kg diet, and after the end of the treatment with 2 mg T4/kg diet. 5. These results provide some evidence for an inhibitory effect of large doses of T4 on the reproductive function in the adult cockerel. Although the possibility of a direct effect of T4 on the testes cannot be excluded, T4 is likely to act, at least in part, at the hypothalamo-pituitary level, and not through a reduction in the pituitary sensitivity to LHRH.

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.

Comparison of various characteristics of duration of fertility in hens.

1. Maximum duration (Dm, number of days post-insemination until last fertile egg) and efficient duration (De, number of days post-insemination until first infertile egg) of fertility, number of fertile eggs (F), dead embryos and hatched chicks (H) during the 21 d following the latter of two intravaginal inseminations (with 125 x 10(6) spermatozoa) on two consecutive days were measured in a total of 2549 layer-type hens at three ages (starting at 30, 44 and 55 weeks of age). 2. De and Dm were highly correlated (0.46 less than or equal to r less than or equal to 0.67). Both De and Dm were also well correlated with F (0.45 less than or equal to r less than or equal to 0.80) and H (0.45 less than or equal to r less than or equal to 0.76) whereas correlations between numbers of dead embryos and other variables were very low and often not significant (0.04 less than or equal to r less than or equal to 0.29). 3. The highest repeatabilities between hen ages were observed for F (0.34 less than or equal to r less than or equal to 0.49) and H (0.36 less than or equal to r less than or equal to 0.48) and the lowest for numbers of dead embryos (0.02 less than or equal to r less than or equal to 0.28). 4. Because of low fertility 18 d after insemination, the period over which measurements were made could have been reduced by 3 d without significant differences in the ranking of the females. 5. The number of perivitelline spermatozoa found in eggs laid on day 2 is not a good predictor of duration of fertility but could allow the culling of hens associated with lowest De or Dm.

Effect of different fractions of seminal plasma on the fertilizing ability of fowl spermatozoa stored in vitro.

This paper describes the effects of whole seminal plasma and of dialysed seminal plasma on the fertilizing ability of fowl spermatozoa stored for 24 h at 4 degrees C. The fertilizing ability of fowl semen diluted 1:1 with Beltsville Poultry Semen Extender and stored for 24 h at 4 degrees C was enhanced after replacement of the homologous seminal plasma by the diluent (89 versus 77% fertilization rate). Better results were obtained with seminal plasma dialysed against water before sperm storage to discard the less than 1 kDa or the less than 50 kDa fractions. It was concluded that low molecular weight seminal plasma fractions could damage the fertilizing ability of spermatozoa during storage at 4 degrees C, whereas high molecular weight fractions appeared to enhance fertilizing ability.