caa a22 4500 477117112 CHVBK 20180405111625.0 cr unu---uuuuu 170330e19960601xx s 000 0 eng 10.1007/BF01875575 doi (NATIONALLICENCE)springer-10.1007/BF01875575 Testicular responsiveness to gonadotropic hormone in vitro and Leydig and Sertoli cell ultrastructure during pubertal development of male African catfish ( Clarias gariepinus ) [Elektronische Daten] [W. Schulz, Karlien Lubberink, Matthijs Zandbergen, Coby Janssen-Dommerholt, Jan Peute, Henk Goos] The gonadotropin (GTH)-stimulated testicular androgen secretionin vitro and the ultrastructure of Leydig and Sertoli cells was studied during the pubertal development in male African catfish. Testicular weight increased from less than 1 mg in the ninth week of age to nearly 600 mg in the 28th week. Immature testes (stage I: spermatogonia) were highly sensitive to GTH and secreted very high amounts of androgens per mg of tissue. The secretion per mg tissue decreased gradually in stages II (spermatogonia and spermatocytes) and III (spermatogonia, spermatocytes, and spermatids), but precipitously in stage IV (all germ cell stages, including spermatozoa). However, due to the testicular weight gain, the total androgen output per pair of testes increased slightly in stage III and strongly in stage IV. The sensitivity to GTH decreased with the appearance of haploid germ cells in stage III. Leydig cells but not Sertoli cells showed the ultrastructural characteristics of steroid producing cells. Leydig cell morphology did not change in stages I-III, while in stage IV, more smooth endoplasmic reticulum was present. The ultrastructural characteristics of Sertoli cells did not change prominently. Thus, spermatogonial multiplication and spermatocyte formation takes place when the testicular steroidogenic system is highly active and responsive to GTH; whereas the differentiation of haploid germ cells is accompanied by a reduced responsiveness to GTH and by the secretion of several-fold lower androgen amounts per mg of tissue. Kugler Publication, 1996 African catfish ( Clarias gariepinus ) nationallicence puberty nationallicence gonadotropin responsiveness nationallicence androgen secretion nationallicence ultrastructure nationallicence testis nationallicence Schulz W. Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Lubberink Karlien Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Zandbergen Matthijs Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Janssen-Dommerholt Coby Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Peute Jan Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Goos Henk Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut Fish Physiology and Biochemistry Kluwer Academic Publishers 15/3(1996-06-01), 243-254 0920-1742 15:3<243 1996 15 10695 https://doi.org/10.1007/BF01875575 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01875575 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Schulz W. Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Lubberink Karlien Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Zandbergen Matthijs Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Janssen-Dommerholt Coby Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Peute Jan Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Goos Henk Department of Experimental Zoology, Research Group Comparative Endocrinology, University of Utrecht, Faculty Biology, Padualaan 8, 3584 CH, Utrecht, The Netherlands aut NATIONALLICENCE 773 0- Fish Physiology and Biochemistry Kluwer Academic Publishers 15/3(1996-06-01), 243-254 0920-1742 15:3<243 1996 15 10695 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer