عنوان مقاله [English]
In general, the testes in the Hynobiidae Family are slender. In urodela, the testis is organized in lobes increasing throughout the cephalocaudal axis during maturity. The anuran testis is organized in tubules. Spermatogenesis occurs in cysts composed by Sertoli cells enveloping germ cells at synchronous stages. Moreover, in numerous species, germ cell progression lasts a year, defining the sexual cycle. Due to the above quoted features, research on factors regulating germ cell progression in amphibians may reach greater insight compared to the mammalian animal models. In the present research, stages in spermatogenesis in Paradactylodon are identified and structurally described for the first time. To this end, 16 specimens of Paradactylodon gorganensis were captured and transferred to laboratory. The species is only found in the Shir-Abad Cave and the stream flowing from it, 60 km east of Gorgan (36 57' N, 55 01' E), in the eastern part of Alborz Mountains, in Golestan Province, northern Iran. After macroscopic analyses and obtaining the testicular fragments, the material was submitted to the histological routine to be included in paraffin and staining with haematoxylin/eosin. Anatomical studies showed that, in this species testis is slender and milk-white; and average length and diameter of active testis were 32.76 mm and 4.77 mm, respectively. Microscopic analyses studies showed that, in this species testis is ampullar and spermatogenesis occurs in cysts developed within seminiferous lobules. Each of these units clusters cells in the same stage of differentiation and with a synchronism development, common characteristic in the amphibians. In the germ tissue, the primary spermatocytes (mean 5.511 ± 0.537 μm) are the biggest spermatogenetic cells. With the cellular differentiation and proliferation, succeeded the other cellular types (spermatogonia, spermatocytes II, spermatids I and II, and spermatozoa) with a cystic organization, that is, groups of cells associated with Sertoli cells, forming the spermatogenetic cysts or spermatocysts. The spermatogenetic lineage cells were differentiated and identified according to the cellular and cystic morphology.