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The aim of the present study was to evaluate the signaling pathways involved in the follicle-stimulating hormone (FSH) regulated mitogenic activity. For this purpose, 18-d-old chick embryo testis cells were dissociated and cultured for 60 h on polycarbonate membranes. The culture medium was Dulbecco modified Eagle's medium with or without high pure human FSH (hFSH), human recombinant FSH, or different regulators of tyrosine kinase activity as herbimycin A and genistein, or serine/threonine kinases [cyclic adenosine monophosphate (cAMP)-dependent protein serine kinase and protein kinase C] as cAMP, phorbol myristate, and forskolin. In some experiments the regulators were added simultaneously with hFSH. The [3H]-thymidine incorporation was used as an indicator of DNA synthesis. In addition, fragments of chick embryo testis were cultured in the presence or absence of FSH or herbimycin A, and 5-bromo-2'-deoxy-uridine was added to identify the proliferating cell subpopulations. The effect of hFSH on [3H]-thymidine incorporation began at 24 h, and the increment was significant at 36 and 60 h of culture. The hFSH as well as human recombinant FSH significantly stimulated [3H]-thymidine incorporation to testicular cells. The 5-bromo-2'-deoxy-uridine technique showed a high signal in pericordonal and interstitial cells of the hFSH-treated groups, confirming the results obtained using [3H]-thymidine uptake. The treatment with the tyrosine kinase inhibitor herbimycin A increased the [3H]-thymidine uptake, but genistein did not. Regulators of PKA such as cAMP and forskolin, as well as PKC regulators and the phorbol ester phorbol myristate, did not influence cell proliferation. In summary, an inhibitor of tyrosine kinase, herbimycin A, induced per se an increment in chick embryo testis cell proliferation, a fact that strongly suggests that tyrosine kinase signaling pathway functions by inhibiting the proliferation of these cells. On the other hand, the cAMP-PKA pathway had no significant role during the embryonic stage of chick embryo testis. Our results also showed that the effect of FSH on chick embryo cell proliferation occurs mainly in pericordonal and interstitial testis cells.

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Ramón Zacarías Ponce de León, ¿Cómo se forman las palabras? Claves de combinación, México, Universidad Nacional Autónoma de México, 2018, 90 pp. ISBN: 978 607 300 4992.