Browsing by Subject "Sertoli cells"

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    Effects of hypothyroidism on anti-mullerian hormone expression in the prepubertal rat testis
    (Murcia : F. Hernández, 2008) Chamindrani Mendis-Handagama, S.M.L.; Siril Ariyaratne, H.B.
    Differentiation of adult Leydig cells (ALC) in the prepubertal rat testis is stimulated by thyroid hormone (Thy) and inhibited by the Anti-Mullerian Hormone (AMH) produced by the immature Sertoli cell (SC). As Thy induces SC maturation in the prepubertal rat testis, we hypothesized that Thy stimulation of ALC differentiation is mediated via inhibition of AMH production by the SC with their maturation. If this hypothesis is true, AMH production by the prepubertal Sertoli cells in hypothyroid rats should not decline immediately after birth as in euthyroid rats, but should be maintained throughout the hypothyroid period at a similar or higher level to that of day 1 rats. This concept was tested using control rats of postnatal days (pd) 1, 7 and 14 and hypothyroid (fed 0.1% propyl thiouracil/PTU to lactating mothers) rats of pd7 and pd14. Presence of AMH in SC was examined by immunocytochemistry for AMH. Results demonstrated that testes of pd1 rats had intense AMH positive labeling exclusively in cytoplasm of SC. In testes of pd7 and pd14 control and PTU rats, a positive but weak labeling was also observed in cytoplasm of some SC; Germ cells and testicular interstitial cells were negative for AMH at all tested ages in both experimental groups. These findings suggest that AMH production by the prepubertal SC is independent of Sertoli cell maturation and not regulated by Thy. Therefore, Thy regulation of ALC differentiation in the prepubertal rat testis is unlikely to be mediated via inhibition of AMH produced by the SC with their maturation.
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    The prepubertal testis: a quiescent or a silently active organ?
    (Murcia : F. Hernández, 1999) Rey, R.
    The development of the testis is characterised by dramatic changes between birth and adulthood. The most conspicuous changes take place during puberty, when the seminiferous tubule diameter increases significantly owing to an important proliferation of germ cells, giving rise to spermatozoa, and to the development of a tubular lumen; in the interstitial tissue characteristic Leydig cells appear and secrete high levels of testosterone. These pubertal changes of the testis can be detected clinically since they result in testicular volume and serum androgen level increments. The prepubertal testis has classically been defined as a quiescent organ. However, since adequate stereological methods for microscopic analysis are available, it has been shown that the male gonad triplicates its volume between birth and the onset of puberty. Sertoli cells and spermatogonia proliferate intensely; this is critical for the development of quantitatively normal adult spermatogenesis. Seminiferous tubule volume increases owing to an increment in tubular length, not diameter. Sertoli cells are also functionally active during childhood: they produce high amounts of anti-Miillerian hormone during the whole prepubertal period, and inhibin B until the age of 2-4 years. Anti-Miillerian hormone and inhibin seem to play a role as modulators of the proliferation and differentiation of Leydig cell precursors.