Gonadal function in young adults after surgical treatment of cryptorchidism.

In a follow-up study of 48 young men who had been surgically treated for cryptorchidism before puberty testicular function was assessed by examining the genitalia, testicular volume, secondary sex characteristics, semen, plasma luteinising hormone (LH) and follicle-stimulating hormone (FSH) concentrations after luteinising hormone-releasing hormone stimulation, and plasma testosterone concentrations. Clinical androgen effects were normal. The mean testicular volume of both testes was in the low normal range in those who had had unilateral cryptorchidism and below normal in those who had had bilateral cryptorchidism. Of 37 patients whose sperm counts were recorded (14 bilateral) six showed azoospermia (all bilateral), five had severe oligospermia (four bilateral), and 10 had moderate oligospermia (one bilateral). In nearly all those who had had bilateral cryptorchidism and most of those who had had unilateral cryptorchidism plasma gonadotrophin levels were increased. Four cases of possible partial LH deficiency were identified. Plasma testosterone concentrations were normal in all except two patients.     

Serum and semen levels of immunoreactive prolactin, LH and FSH in normospermic, oligospermic and azoospermic men with obstructive infertility prior to and after vasoepididymostomy.

Attempts were made to validate RIA for prolactin (PRL), LH and FSH in semen from normospermic, oligospermic and azoospermic subjects. The RIA used to measure PRL and LH in semen fulfilled the criteria of reliability, whereas low levels of FSH in semen precluded the validation of FSH assay in semen. Semen levels of PRL and LH were significantly (P < 0.05) higher than serum levels in all groups of subjects investigated. Semen levels of FSH in azoospermic men after vasoepididymostomy (VEA), were significantly (P < 0.05) higher compared to azoospermic men prior to surgery. Serum levels of PRL were significantly higher (P < 0.05) in normospermic men compared to oligospermic and azoospermic men prior to and after surgery. Semen levels of PRL in normospermic men were comparable with oligospermic and azoospermic subjects prior to and after surgery. Serum levels of LH in oligospermic and azoospermic men who did not undergo surgery and in men reporting oligospermia after VEA were comparable to normospermic subjects but in men showing azoospermia post surgically, serum LH levels were significantly (P < 0.005) elevated. Semen levels of LH in men reporting azoospermia before surgery and in subjects showing oligospermia or azoospermia post surgically were significantly lower (P < 0.05) compared to men with normal sperm count. Serum levels of FSH were significantly elevated (P < 0.05) compared to semen levels in oligospermic men prior to surgery but this increase was not seen in post VEA subjects. These results were discussed.     

Recueil chirurgical de spermatozoïdes dans un groupe de 50 patients avec un antécédent de cryptorchidie bilatérale: facteurs pronostics d’extraction

Bilateral cryptorchidism is a severe factor of male infertility. We evaluated the results of testicular sperm extraction in 50 men with nonobstructive azoospermia associated with cryptorchidism between 1995 to 2001. We evaluated clinical parameters predictive of successful sperm extraction. Serum follicle stimulating hormone (FSH) was elevated in 67% of cases and testicular volume was decreased in 70% of cases, confirming the secretory origin of the azoospermia. Serum follicle stimulating hormone (FSH), testicular volume and histological parameters were examined as predictive factors for sperm recovery. The positive sperm recovery rate was 68%. As in the population of men with nonobstructive azoospermia, the sperm recovery rate for patients with a history of orchidopexy is approximately 68% and there are currently no clinical parameters predicting successful sperm retrieval in this subpopulation of patients.     

Follicle-stimulating hormone may predict sperm retrieval rate and guide surgical approach in patients with non-obstructive azoospermia

Testicular sperm aspiration- (TESA) or micro-dissection testicular sperm extraction- (MD-TESE) combined intracytoplasmic sperm injection (ICSI) was the only option for non-obstructive azoospermia (NOA) patients to have a biological offspring and they had different success rates in sperm retrieval. Our study aimed to find predictor(s) for predicting the sperm retrieval rate (SRR) in NOAs and guide clinicians in choosing different surgical approaches, TESA or MD-TESE for NOAs. 294 NOAs who had undergone TESA or MD-TESE were divided into TESA group and MD-TESE group. Depending on sperm retrieval, each group was divided into two subgroups: successful subgroups and failure subgroups. They respectively were 24 cases and 131 cases, 53 cases and 86 cases. Clinical data, including body mass index (BMI), testicular volume, and serum hormone levels, were analyzed in a retrospective manner. The results showed that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels and SRR were lower in TESA group as compared to these in MD-TESE group, while testicular volume was higher (P < 0.05). The surgical approach of sperm retrieval significantly affected the SRR (P < 0.05). In TESA subgroups, testicular volume, FSH and LH differed significantly (P < 0.05). In MD-TESE subgroups, the level of FSH and LH differed significantly between both groups (P < 0.05). Using logistics regression, we found a negative correlation (β=-0.083) between FSH and the SRR in TESA group but a positive correlation (β = 0.064) in MD-TESE group (P < 0.05). In conclusion, serum FSH level can predict the SRR of NOAs and guide the clinicians while selecting the suitable surgery approach for NOAs.     

Reproductive toxicity with and without LHRHA administration during adjuvant chemotherapy in patients with germ cell tumors.

In order to evaluate the protective efficacy of an agonist of luteinizing hormone releasing hormone (LHRHA) on spermatogenic stem cells, we undertook a prospective study in patients with germ cell tumors. Following orchiectomy and unilateral lymph node dissection all patients received adjuvant chemotherapy consisting of 2 courses of PVB regimen (cisplatin, vinblastine and bleomycin). Six men were treated with LHRHA (d-Ser-(TBU)6 LHRH ethylamide) before, during and after PVB chemotherapy. Eight patients without LHRHA protection served as controls, receiving the identical chemotherapy. Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone were within normal limits before therapy in all patients. In 6/6 protected patients, serum levels of FSH, LH and testosterone were effectively suppressed during pre-chemotherapeutic LHRHA administration. All protected patients showed elevated serum FSH levels and azoospermia after cessation of chemotherapy and LHRHA treatment due to germ and stem cell loss. Median FSH level and sperm density of the protected group normalized within 24 months after chemotherapy. In all unprotected patients elevated FSH values and azoospermia also occurred after chemotherapy. Likewise, median FSH level and sperm density normalized spontaneously in this group within 24 months after chemotherapy. Our results suggest completely reversible reproductive toxicity two years after 2 courses of adjuvant chemotherapy in all patients. Administration of LHRHA during chemotherapy seems to have no protective effects on germ cells since both groups developed reproductive toxicity. Furthermore, recovery time was identical in the protected and unprotected patients. FSH and LH could be used as diagnostic markers to assess the degree and duration of reproductive and endocrine gonadal toxicity after chemotherapy.     

Immunoactive inhibin as a marker of Sertoli cell function following cytotoxic damage to the human testis

Sertoli and Leydig cell functions were evaluated in men with testicular damage due either to cytotoxic chemotherapy (CCT) or radiotherapy (XRT). Serum immunoactive inhibin, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone concentrations were measured in 15 men (19-50 years) who had received 6-10 courses of combination CCT (mustine, vinblastine, procarbazine and prednisolone) for Hodgkin's disease 1-8 years earlier and 18 men (21-49 years) who had undergone unilateral orchidectomy for testicular seminoma followed by XRT (30 Gy) to the remaining testis, 1-4 years earlier. Normal men (n = 16, 19-36 years) acted as controls. Median inhibin (422 U/l) and testosterone (16.0 nmol/l) levels in the CCT-treated group were not significantly different from controls, whereas median FSH (14.5 IU/l) and LH (10.0 IU/l) levels were higher (p less than 0.0001 and p less than 0.001) than normal (2.9 and 5.5 IU/l). The median inhibin/FSH (I/FSH) ratio in the patients was lower (p less than 0.0001) than in the controls (33.8 vs. 187.0) as was the testosterone/LH (T/LH) ratio (1.7 vs. 3.8, p less than 0.001). In the XRT-treated group, both median inhibin (194.5 U/l) and testosterone (12.7 nmol/l) levels were lower (p less than 0.0001 and p less than 0.01) than normal (532.8 U/l and 20.0 nmol/l) in the presence of greatly elevated FSH (26.0 IU/l) and LH (14.5 IU/l) levels. In conclusion, CCT-induced testicular damage is associated with subtle Sertoli and Leydig cell dysfunction demonstrated by the reduced I/FSH and T/LH ratios; however, compensatory mechanisms maintain normal testosterone and inhibin levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hormone levels in serum and seminal plasma of men with different types of azoospermia

Hormone concentrations in the serum and seminal plasma of 15 normozoospermic, 17 excretory azoospermic and 14 secretory azoospermic men were measured. The results indicate that: (a) serum FSH and LH levels are markedly elevated in secretory azoospermia, as compared with excretory azoospermia and normozoospermia; (b) serum 17 alpha-hydroxyprogesterone levels are somewhat raised in secretory azoospermia as compared with excretory azoospermia and normozoospermia; (c) serum testosterone levels are lower in both types of azoospermia with respect to normozoospermia; (d) in secretory azoospermia the oestradiol serum levels are relatively high and dihydrotestosterone serum levels relatively low, whereas the serum levels of these hormones in excretory azoospermia are similar to those in normozoospermic men; (e) in the seminal plasma of azoospermic patients the levels of prolactin, progesterone, testosterone, dihydrotestosterone and oestradiol were depressed, but only dihydrotestosterone levels could be of value in differentiating types of azoospermia because they are lower in secretory azoospermia. We suggest that the measurement of FSH, LH, 17 alpha-hydroxyprogesterone, dihydrotestosterone and oestradiol in serum and dihydrotestosterone in seminal plasma may be used in the differential diagnosis between secretory and excretory azoospermia when invasive tests are unavailable.     

Fertility after unilateral cryptorchidism. Paternity, time to conception, pretreatment testicular location and size, hormone and sperm parameters.

OBJECTIVE: To further evaluate whether fertility is decreased among a cohort of men with previous unilateral cryptorchidism as compared with a control group of men. SUBJEcTS AND METHODS: Formerly unilateral cryptorchid men who had undergone orchiopexy between the years of 1955 and 1975 at the Children's Hospital of Pittsburgh and a control group of men who were matched for age of an unrelated surgery at the same institution were evaluated by review of medical records and by completion of a questionnaire. 359 previously cryptorchid men were identified as having attempted paternity. Of these men, 320 had information concerning preoperative testicular location and 163 for preoperative testicular size. 106 of these men had levels of testosterone, inhibin B, FSH, and LH measured, while 95 of the men had semen analyses. RESULTS: Among men who had attempted paternity, there was no statistical difference in success of paternity between the previously unilateral group (89.7%) and the control group (93.7%). There was no difference in the mean time to conception (7.1 +/- 0.7 months for the unilateral group vs. 6.9 +/- 2.3 for the control group). Within the unilateral group in regard to success at paternity, no difference was found compared with the age of orchiopexy, preoperative testicular location, or preoperative testicular size. Inhibin B levels were lower among the unilateral group. FSH, LH, testosterone, sperm density, motility and morphology were not different, but considerable variation was noted within the cryptorchid group. CONCLUSIONS: In this continued evaluation of a cohort of previously cryptorchid men who had undergone unilateral orchiopexy, paternity does not appear to be significantly compromised after unilateral cryptorchidism. Unilateral cryptorchidism appears to be one of several factors contributing to infertility, similar to those found in the general population. No correlation was found between success at paternity and the age of orchiopexy, preoperative testicular size or preoperative testicular location. Inhibin B levels were lower while FSH, LH, T and sperm parameters did not differ.     

Inhibin B levels in adolescents and young adults with type 1 diabetes

OBJECTIVE/METHODS: To assess exocrine and endocrine testicular function in subjects with diabetes, we evaluated serum inhibin B, gonadotrophins and testosterone levels in 33 male adolescent and young adult patients affected by type-1 diabetes (age 21.0 +/- 5 years; range 14.2-33.3), with a mean disease duration of 12.7 +/- 5.8 years (range 1.5-25.3) and various metabolic control (HbA1c 7.8 +/- 1.5%; range 5.5-13.2) and compared them with those of an age-matched group of 36 healthy control subjects (age 19.5 +/- 4.1 years; range 13.6-28.1). Both patients and controls had a testicular volume >or=15 ml. Inhibin B was measured by ELISA method. RESULTS/CONCLUSION: Diabetics and controls had comparable inhibin B (203 +/- 74 vs. 221 +/- 69 pg/ml, respectively) and follicle-stimulating hormone (FSH) levels, while luteinizing hormone (LH) and testosterone levels were significantly higher in the diabetic group. Inhibin B was negatively correlated both in patients and controls with FSH, while a negative correlation with LH was found only in the diabetic group. We conclude that our young diabetic males, after a mean disease duration of 12 years and various metabolic control, had inhibin B and FSH levels comparable to those of normal subjects. Therefore, they seem to have a regular testicular function and in particular a normal seminiferous tubule/Sertoli cell activity despite sustained hyperglycemia.     

Meiotic arrest at first spermatocyte level: A new inherited infertility disorder

Summary Three 46,XY phenotypically male, azoospermic brothers out of thirteen sibs from a consanguineous marriage were studied and found to have a unique pattern of testicular histology with arrest of spermatogenesis at the pachytene stage of primary spermatocytes. Endocrinological evaluation showed elevated plasma luteinizing (LH) and normal to elevated follicle-stimulating (FSH) hormones, positive gonadotropin pituitary response to luteinizing hormone-releasing hormone, depletion of LH and FSH levels by exogenous testosterone (T) administration, normal levels of T and dihydrotestosterone hormones, and elevation of T after stimulation with human chorionic gonadotropin hormone. Electrophoretic assay of lactic dehydrogenase isozymes did not reveal band C₄ in semen or testicular tissue. These traits seem to constitute a hitherto undescribed form of infertility in which spermatogenesis arrest at the first spermatocyte level is the main feature. The parental consanguinity suggests autosomal recessive inheritance.     

Relationship between sperm count, serum gonadotropins and testosterone levels in normo-, oligo- and azoospermia

In 92 men with normozoospermia (greater than 40 X 10(6)/ml), 105 with slight oligozoospermia (greater than 10 X 10(6)/ml), 100 with severe oligozoospermia (less than 10 X 10(6)/ml) and 56 with azoospermia, serum testosterone, LH and FSH were measured radioimmunologically. With an increasing degree of reduction of spermatozoa, a decreasing testosterone level and increasing LH and FSH levels could be demonstrated. In normozoospermia, between 40 and 140 X 10(6)/ml, a direct correlation was found between FSH and sperm count, and, in the group between 40 and 100 X 10(6)/ml, a direct correlation between T and sperm count. A disturbed LH:T balance is often observed which beside decreased serum T levels demonstrates a testicular deficiency in androgen production.     

Seasonal changes in plasma concentrations of immunoreactive inhibin and testicular activity in male Japanese monkeys

Seasonal changes in plasma immunoreactive (ir-) inhibin, testosterone, LH, and FSH concentrations were examined in five sexually mature male Japanese monkeys (Macaca fuscata fuscata) housed indoors individually, to explore the reproductive cyclicity in the male. Blood samples were collected monthly throughout one year, and testicular size, semen volume, and number of sperm in the semen were ascertained at the same time in the same animals. Semen samples were obtained by penile electrostimulation. The results showed a clear seasonal increase in all parameters: plasma ir-inhibin, testosterone, testicular size, semen volume, and total number of sperm in the liquid portion of the semen during the autumn and winter months in synchrony with the natural breeding season. In contrast, plasma LH and FSH remained unchanged throughout the year, although plasma FSH tended to increase during the breeding season concomitant with an increase in plasma ir-inhibin. A significant positive correlation between FSH and ir-inhibin was observed in two of five monkeys. The positive correlations between plasma ir-inhibin and testicular activities during both the developing and regressing phases of the testicular cycle indicate that plasma ir-inhibin is a useful indicator of testicular activity as well as an indicator of Sertoli cell function in the Japanese monkey.     

L’Inhibine B sérique, marqueur sensible de la production spermatique chez l’homme

Several recent papers indicate that the blood concentration of inhibin B measured by the dimeric assay is a marker of human spermatogenesis. The aim of the present study was to validate the dimeric assay in our hospital. For this purpose, we studied a population of 106 patients attending our infertility clinic. We found that serum inhibin B levels were positively correlated with the level of sperm production as reflected by the sperm concentration and negatively correlated with serum FSH levels. Serum inhibin B concentrations were found to be superior to FSH levels for discriminating between subgroups of patients with different levels of sperm production. For example, the differences in the inhibin B levels in severe oligozoospermia (< 5×106 sperm/ml) compared to non-obstructive azoospermia were more pronounced than the differences in FSH (p=0.0002 vs p=0.007, respectively). Overall, the results obtained in the present study were similar to those reported in other studies based on the same assay. Serum inhibin B levels in patients with non obstructive azoospermia were ten times lower than in patients with normal sperm concentrations. From a practical point of view, the measurement of serum inhibin B opens up new possibilities for the diagnosis and prognosis of many testicular disorders. Firstly, serum inhibin B determination should be performed whenever reproductive hormones are prescribed. In the particular case of azoospermia, serum inhibin B concentrations appear to be particularly useful to distinguish between obstructive and non-obstructive situations. Finally, according to a recent publication, a serum inhibin B cut-off value (> 40 pg/mL) could predict the success of testicular sperm extraction in patients with non-obstructive azoospermia. Serum inhibin B could therefore represent a unique non-invasive marker of focal hypospermatogenesis in men with non-obstructive azoospermia, who are candidates for intracytoplasmic sperm injection (ICSI) and a useful early marker to monitor possible recovery of spermatogenesis after chemotherapy or radiotherapy.     

Effect of fetal hypothyroidism on MyomiR network and its target gene expression profiles in heart of offspring rats

Currently, azoospermia is one of the most common diseases of male infertility. Stem cell research is the new hope for novel therapy with a higher degree of safety and lower cost. This study aimed to investigate the effect of umbilical cord blood-derived stem cells (” and mesenchymal “UCB-MSCs”) and mono-cell layer implanted into the induced azoospermic mice testis. Stem cells were isolated from umbilical cord blood and CD34+ve cells were separated from negative one by Mini MACs column. At 5th week after single injection of busulfan, stained mesenchymal (CD34-ve), hematopoietic stem cells (CD34+ve) and their conjugate (mono-cell layer) were injected locally into testis. At the end of the study, MSCs group showed that mRNA levels of genes related to meiosis (Vasa, SCP3, and PgK2) were increased with significant decrease of FSH and LH levels, compared to control group. Histologically, most of the tubules restored normal architecture. In contrast, HSCs and mono-cell layer groups showed statically insignificant change of FSH, LH, and gene expression, compared to control group. Histologically, distorted seminiferous tubules, with reduction in sperm content, and interstitial mononuclear cellular infiltration were seen. There was significant increase in the optical density of PCNA immune reaction in MSCs group than azoospermia, HSCs, and mono-cell layer, while there was non-significant difference between MSCs and control group. The present study suggested that injection of MSCs into chemotherapeutic-induced azoospermia in mice improved testicular failure; histologically and functionally, by restoration of spermatogenic gene expression while HSC and mono-cell layer showed no effect on spermatogenesis added to that mono-cell layer may induce testicular tissue damage.     

Testicular and blood steroid levels in aged men

In this study, we have evaluated the hypophyso-gonadal axis in three groups of men aged 60-69, 70-79 and 80-91 years by measuring the intratesticular concentrations of several steroids (pregnenolone, progesterone, DHEA, DHEA-S, testosterone, estradiol) and serum levels of FSH, LH, testosterone, estradiol and sex hormone binding globulin (SHBG). The histological examination of testes revealed normal spermatogenesis in all examined samples. No significant changes in serum hormone and SHBG concentrations as well as in testicular steroid contents among the three groups of patients were found. However, the mean serum SHBG level was three times higher in the oldest men than in other groups and a positive correlation between patient's age and serum SHBG was observed. Therefore, the bioavailability of estradiol in the oldest men was likely diminished. Consequently, the hormonal status in aged men is rather unchanged but great variations observed between patients imply special cautious when the SHBG and estradiol levels are concerned.     

男性不育与Y染色体

目的:观察精子数目异常与小Y染色体及内分泌性腺激素水平。方法:对262名少精及无精症患者检测染色体,并对其中11例小Y染色体及随机抽取的15例Y染色体正常的患者运用磁性分离酶免疫测定法分别检测性腺激素。结果:小Y染色体检出率为4.19%(11/262),其内分泌性腺激素均呈高卵泡刺激素、高黄体生成素和低睾酮水平,与Y染色体正常的无精及少精症患者相比较,差异有显著性(P<0.05)。而小Y染色体不同精子数组各内分泌性腺激素比较,差异无显著性(P>0.05)。结论:精子数目异常可能与小Y染色体有关,小Y染色体基因改变可能是导致其内分泌性腺激素的变化因素。     

Fertility after bilateral cryptorchidism. Evaluation by paternity, hormone, and semen data.

PURPOSE: Evaluation of the fertility of a cohort of formerly bilaterally cryptorchid men in comparison with a group of formerly unilaterally cryptorchid men, and a group of control men. MATERIALS AND METHODS: Using a detailed questionnaire concerning paternity and factors related to paternity, a cohort of formerly bilateral cryptorchid men were studied and compared with men who had undergone orchiopexy for unilateral cryptorchidism, and a group of control men. All study subjects had had surgery at the Children's Hospital of Pittsburgh, Pittsburgh, Pa., between 1955 and 1975. A subset of the full cohort underwent clinical evaluation that included a physical examination, serum hormonal determination and semen analyses. RESULTS: Paternity rates are significantly lower among the formerly bilaterally cryptorchid men who have attempted to father a child (65.3%) as compared to the formerly unilaterally cryptorchid (89.7%; p < 0.001) and control men (93.2%; p < 0.001). Differences in the ability to father children are also apparent when semen and hormone levels are compared between the three groups. The bilateral group has significantly lower sperm density and inhibin B levels, and higher FSH and LH levels, than the unilateral and control groups. CONCLUSIONS: Men born with bilateral cryptorchidism have severely compromised fertility in adulthood. This reduction in fertility is clearly shown in comparisons of both paternity rates, and in semen and hormone analyses, between the formerly bilateral, formerly unilateral, and control groups.     

Photoperiod entrainment of testosterone, luteinizing hormone, follicle-stimulating hormone, and prolactin cycles in rams in relation to testis size and semen quality

Adult rams were exposed to photoperiod treatments over 2 years to study the influence of light regimes on pituitary-testicular activity and semen quality. Initially, all rams (12 per group) were exposed to 3 months of long days (16L:8D). Group 1 was then exposed to a regime of continuous short days (8L:16D) and Groups 2, 3, and 4 were exposed to 4 months of short days alternated with 1, 2, or 4 months, respectively, of long days. Every 2 weeks, serum hormone levels and scrotal circumference were determined and semen quality was evaluated. Regular cycles in pituitary and testicular activities corresponding to the period of the lighting regime resulted in Groups 2, 3, and 4, but not in Group 1. In general, the change from long days to short days induced increases in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels, scrotal size and sperm numbers and a decrease in prolactin. The reverse occurred after subsequent exposure to long days. After 4 months of long days, testicular regression was complete, but when long-day exposure was reduced, less regression occurred. With continuous exposure to short days, FSH and testosterone remained above basal levels, prolactin levels were depressed, scrotal size remained near the maximum, and elevated numbers of motile sperm were sustained.     

Changes in circulating levels of immunoreactive follicle stimulating hormone, luteinizing hormone, and testosterone during sexual development in the rhesus monkey, Macaca mulatta

Basal serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) and the responsiveness of these hormones to a challenge dose of luteinizing hormone releasing hormone (LHRH), were determined in juvenile, pubertal, and adult rhesus monkeys. The monkey gonadotrophins were analyzed using RIA reagents supplied by the World Health Organization (WHO) Special Programme of Human Reproduction. The FSH levels which were near the assay sensitivity in immature monkeys (2.4 +/- 0.8 ng/ml) showed a discernible increase in pubertal animals (6.4 +/- 1.8 ng/ml). Compared to other two age groups, the serum FSH concentration was markedly higher (16.1 +/- 1.8 ng/ml) in adults. Serum LH levels were below the detectable limits of the assay in juvenile monkeys but rose to 16.2 +/- 3.1 ng/ml in pubertal animals. When compared to pubertal animals, a two-fold increase in LH levels paralleled changes in serum LH during the three developmental stages. Response of serum gonadotrophins and T levels to a challenge dose of LHRH (2.5 micrograms; i.v.) was variable in the different age groups. The present data suggest: an asynchronous rise of FSH and LH during the pubertal period and a temporal correlation between the testicular size and FSH concentrations; the challenge dose of LHRH, which induces a significant rise in serum LH and T levels, fails to elicit an FSH response in all the three age groups; and the pubertal as compared to adult monkeys release significantly larger quantities of LH in response to exogenous LHRH.     

Puberty in the male chimpanzee: time-related variations in luteinizing hormone, follicle-stimulating hormone, and testosterone

The onset of pubertal testicular growth (Po) occurred in 12 out of 20 male chimpanzees surveyed monthly for at least 3.7 yr. When animals were synchronized according to Po, the mean weight gain was found to be higher before than after Po, and testicular volume started to rise immediately after Po. The earlier significant hormonal events were a rapid rise in LH and a slight testosterone increase occurring 6 mo before Po. Thereafter, the levels of LH remained elevated while testosterone continued to rise in parallel with the testicular volume. FSH levels increased suddenly at Po, 6 mo after the LH increase. FSH remained elevated for only 9 mo, then dropped to prepubertal levels. The dissociation between onsets of pubertal increases in LH and FSH secretions suggests that the complete reawakening of the hypothalamic-pituitary unit lasts several months. The secondary drop of FSH, occurring at the time of spermarche, may be induced by factor(s) secreted by the testis.