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At least 469 records · Page 26Linked to original sources
PubMed1997

Effect of vitamin A excess on germ cell development in prepubertal rat testis.

Vitamin A in graded doses of 125, 250 and 375 U.S.P./kg body wt, po, for 10 days (d 21-30) drastically reduced the testicular weight by 25 to 62% and seminiferous tubular diameter by 14 to 35% in prepubertal rats in lowest and highest doses of the treatment. The treatment induced disproportionate enlargement of nuclei and cytoplasm of the germ cells; predominantly the preleptotene and pachytene spermatocytes. These abnormal germ cells, often with 2 or 3 nuclei displayed vacuolated cytoplasm surrounding pyknotic or granulated or dispersed chromatin granules within the nuclei in a dose proportionate manner. The round spermatids were the most sensitive cell types which completely disappeared in two higher doses of treatment. Vacuolation of Sertoli cell cytoplasm in about 25% of the tubules with associated increase in intertubular space was also observed in rats treated with the highest dose of the vitamin. Circulatory levels of FSH, LH and testosterone remained unaltered following the vitamin excess treatment. Therefore, it is suggested that excess vitamin A even for shorter duration like the present one is detrimental to developing cell types and prevents the progress of the spermatogenic process beyond the round spermatid stage.

Animals↗
PubMed2002

SOX9 has both conserved and novel roles in marsupial sexual differentiation.

In addition to an essential role in chondrogenesis, SOX9 is a highly conserved and integral part of the testis determining pathway in human and mouse. To determine whether SOX9 is involved in sex determination in noneutherian mammals we cloned a marsupial orthologue and studied its expression. The tammar wallaby SOX9 gene proved to be highly conserved, and maps to a region of the tammar genome syntenic to human chromosome 17. Marsupial SOX9 transcripts were detected by RT-PCR in the developing limb buds and both the developing ovary and testis from the first sign of gonadal development through to adulthood. Northern blot, in situ hybridisation, and immunohistochemical analyses showed that SOX9 reaches high levels of expression in the developing testis, where it is confined to the Sertoli cell nuclei, and the brain. This is similar to the expression pattern seen in human and mouse embryos and is consistent with a conserved role for SOX9 in vertebrate brain, skeletal, and gonadal development. In addition, SOX9 was expressed in the developing scrotum and mammary gland primordium regions of the tammar up to the time of birth. SOX9 protein was also detected in the developing Wolffian duct epithelium in the male mesonephros. These previously undescribed locations of SOX9 expression suggest that SOX9 may play additional roles in the differentiation of the marsupial reproductive system.

Amino Acid Sequence↗
PubMed1989

Insulin-like growth factor I in the developing and mature rat testis: immunohistochemical aspects.

The distribution of insulin-like growth factor I (IGF-I; somatomedin C) was mapped in testes of different aged rats by using immunohistochemical techniques. The antiserum used, K 624, has been demonstrated to be specific for human IGF-I, as defined by several criteria. Antibodies to the M1 subunit of ribonucleotide reductase, a key enzyme in DNA synthesis, were used to visualize meiotic and mitotic cells. Cytoplasmic IGF-I-like immunoreactivity as demonstrable during the first two postnatal weeks in spermatogenic cells, in Sertoli cells, and in Leydig cells. The IGF-I-like immunoreactivity decreased in the Sertoli and Leydig cells during the third and fourth postnatal weeks, and in adult rats, only spermatogenic cells showed IGF-I-like immunoreactivity. In mature rat testes, the spermatocytes were strongly immunoreactive. During puberty and adulthood, the spermatogonia expressed subunit M1 ribonucleotide reductase immunoreactivity, whereas no IGF-I-like immunoreactivity could be detected. No extracellular immunoreactivity was observed. We propose that IGF-I and/or IGF-I-like substances, possibly formed by primary spermatocytes, are likely to be involved in differentiation processes, but not in the initiation of cell proliferation in adult testes. The autocrine and/or paracrine action of IGF-I and/or IGF-I-like substances may thus have different action in developing testes than in adult testes. Our results do, however, not allow firm statements about whether IGF-I and related substances exert their actions on Sertoli cells or spermatogenic cells.

Aging↗
PubMed1983

Acid phosphatases in the mouse testis: activity changes during development.

The histology and acid phosphatase activities of the developing testes in the mouse, from 4 days of age until maturity, were analyzed. The specific enzyme activity with p-nitrophenyl phosphate as substrate increased after 3 weeks of age and then reached a plateau. Cobalt and zinc markedly increased the specific activity after the third week. After fractionation the testicular homogenate revealed four acid phosphatases. Enzyme I maintained a high activity during the first 3 weeks but steadily declined thereafter. Enzyme II, present in all age groups, showed a moderate increase after the fourth week. Enzymes III and IV were low and declined further during the first 3 weeks with a subsequent increase. This occurred concomitantly with the appearance of spermatids and mature sperm cells. Changes in enzyme activities seem to reflect the alterations in cellular composition of the testis during the developmental process. Enzymes III and IV were probably associated with spermatids and sperm cells.

Acid Phosphatase↗
PubMed1995

Expression profile of Ldh-a in the developing rat (Rattus norvegicus) testis suggests regulation at the translational level.

Expression of Ldh-a and Ldh-c mRNAs was examined in the rat testis. The mRNA levels of both Ldh-a and Ldh-c increase during testicular maturation. In the adult testis, Ldh-a mRNA is expressed maximally in primary spermatocytes. Comparison of the Ldh-a mRNA expression profile with its translation product suggests that this gene is translationally down-regulated during spermatogenesis.

Animals↗
PubMed1998

Gonad development: assembling the mammalian testis.

Mammalian primordial germ cells migrate into gonads of either sex indiscriminately and may be functional even across a species barrier; but certain somatic cell lineages are attracted specifically into the male gonad and are absolutely required for the construction of the seminiferous cords of the testis.

Animals↗
PubMed1987

Proliferation of Sertoli cells during development of the human testis assessed by stereological methods.

Sertoli cells were studied using stereological methods in testes obtained from five children who were stillborn, and 31 individuals between 3 months and 40 years of age, who had suffered from sudden, unexpected death. The mean nuclear volume of the Sertoli cells, the numerical density of Sertoli cells, and the total number of Sertoli cells per individual were determined by point- and profile-counting of 0.5 micron sections. The nuclear volume of Sertoli cells increased from a median of 120 microns3 (range 53-130) during the period of 3 months to 10 years to 210 microns3 (170-260) in adults (greater than 25 years). The numerical density of Sertoli cells decreased from a median of 1200 X 10(6)/cm3 (870-1400) during childhood (3 months to 10 years) to 140 X 10(6)/cm3 (110-260) in adults (greater than 25 years). The total number of Sertoli cells per individual increased significantly from a median of 260 X 10(6) (130-520) during the late foetal period to 1500 X 10(6) (850-2900) in individuals from 3 months to 10 years of age. A further increase was found during puberty as the number of Sertoli cells in adults (greater than 25 years) was 3700 X 10(6) (2500-5600). These results indicate that significant qualitative and quantitative changes in the population of Sertoli cells take place after birth.

Adolescent↗
PubMed2000

Expression of the leptin receptor during germ cell development in the mouse testis.

Leptin, a recently identified hormonal product of the ob gene, is known to regulate appetite, body metabolism, and reproductive functions. We investigated the expression of the leptin receptor (Ob-R) in testes from different age groups. The messenger RNA for Ob-R was found in testes from all age groups using RT-PCR. Using immunohistochemistry, we observed age- and stage-dependent distribution of the Ob-R in mouse testis. In testis of 5-day-old mice, its expression was mainly in type A spermatogonia. In the 20- and 30-day-old testis, Ob-R expression was in the spermatocytes; in the adult testis, it was specific to spermatocytes in stages IX and X of the cycle of the seminiferous epithelium. Five main immunoreactive proteins were detected using Western blot (220, 120, 90, 66, and 46 kDa). The 120-kDa protein was evident only in 20-day-old and older testes, whereas the 90-kDa band was present only in the 5- and 10-day-old testis. Leptin treatment induced phosphorylation of signal transducer and activator of transcription-3 in cultured seminiferous tubules from adult and 5-day-old testes. Our results show for the first time age- and stage-specific localization of a functional Ob-R in testicular germ cells. We hypothesize a direct role for leptin, through phosphorylation of signal transducer and activator of transcription-3, in proliferation and differentiation of germ cells, which may partially explain the infertility observed in leptin-deficient mice.

Aging↗
PubMed1995

Endocrine control of testicular somatic and premeiotic germ cell development in the immature testis of the primate Macaca mulatta.

Four groups(N = 3 per group) of juvenile rhesus monkeys (Macaca mulatta, 14-20 months old) received either vehicle or highly purified human follicle-stimulating hormone (FSH; 10 IU kg-1 day-1), human chorionic gonadotropin (hCG; 250 IU every alternate day) or both hormones for a period of 4 weeks. Testicular volume and weight increased more than twofold after single and more than sixfold after combined hormone treatment. Serum and intratesticular testosterone were at supraphysiological levels in hCG-treated animals and rose even more after combined treatment; a minor elevation of intratesticular testosterone was also observed after FSH treatment. Serum inhibin was elevated after hCG or FSH treatment and increased more than twofold during the first 3 weeks of combined treatment. Semiquantitative analysis of cell numbers showed a statistically non-significant increase in Sertoli cells and Ad- and Ap-spermatogonia after single hormone treatment. Combined treatment induced a further increase in the number of spermatogonia. Leydig cells were only encountered after hCG treatment; their number was more than threefold higher after combined treatment compared with hCG alone. Follicle-stimulating hormone stimulated Sertoli cell and Ap spermatogonia proliferation but did not induce morphological differentiation of Sertoli cells, peritubular cells or Leydig cells. Human CG treatment, however, induced Sertoli cell proliferation and morphological differentiation. It had effects on spermatogonial proliferation but induced differentiation of peritubular cells. Combined treatment initiated the greatest morphological and functional differentiation of Sertoli cells, peritubular cells, Leydig cells and spermatogonia. Flow cytometric analysis confirms an increase of mitotically active cells. The observations show that FSH and testosterone can induce Sertoli cell proliferation. Morphological differentiation of Sertoli cells may be mediated indirectly by environmental and paracrine stimuli released from peritubular cells, whose differentiation is androgen dependent. Leydig cells are stimulated mainly by hCG. Our present and previous data lead us to propose that FSH contributes to the final number and activity of Leydig cells, which secrete immunoreactive inhibin in response to hCG.(ABSTRACT TRUNCATED AT 400 WORDS)

Actins↗