标题：Effect of Sublethal Concentrations of Aqueous Extract of Lepidagathis alopecuroides on Spermatogenesis in the Fresh Water Catfish Clarias gariepinus
摘要：The effect on spermatogenesis of sublethal concentrations of Lepidagathis alopecuroides indiscriminately used for capturing fish was evaluated on fresh water catfish Clarias gariepinus using standard Hematoxylin-eosin histological techniques. Matured testes from 15 adult fish exposed to sublethal concentrations of L. alopecuroides for 21 days were processed by Hematoxylin-eosin histological technique and the effect of the leaf extract on testicular somatic and germ cells of the seminiferous epithelium assessed by light microscopy. Spermatogenesis occurred in cysts and proliferating Spermatogonia B were surrounded by extensions of Sertoli cells. The last mitotic division of the B spermatogonia produced the Preleptotene primary spermatocytes which differentiated in clones through Leptotene, Zygotene, Pachytene to Diplotene, secondary spermatocytes, round spermatids and spermatozoa before spermiation. This sequence of events demonstrates the presence of recognizable cycle of spermiation in Clarias gariepinus . Changes in the germinal epithelium during spermatogenesis showed that sublethal concentrations of this extract induced mitotic inhibition in proliferating spermatogonia populations, inhibited the last mitotic division in B-type spermatogonia and reduced the number of spermatogonia population entering meiotic division. This led to germ cell loss and reduction of primary spermatocytes population, consequently, a decrease in sperm production potential. Exposure of this fish species to sublethal concentrations of Lepidagathis alopecuroides even for short periods induced testis structure alterations and functions including inhibition of spermatogonia A renewal after spermiation. It is thus concluded that freshwater catfish Clarias gariepinus exposed to sublethal concentrations of L. alopecuroides would exhibit reduction in sperm production in the subsequent reproduction cycles.
