Ben Ahmed Raja, Tekaya Saïda, Urbisz Anna Z, Świątek Piotr
Université Tunis El Manar, Faculté des Sciences de Tunis, UR 11ES12 Biologie de la Reproduction et du Développement Animal, 2092 EL-Manar Tunis, Tunisia.
Department of Animal Histology and Embryology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland.
Tissue Cell. 2015 Jun;47(3):242-53. doi: 10.1016/j.tice.2015.03.002. Epub 2015 Mar 11.
This paper presents the process of spermatogenesis in the leech Hirudo troctina Johnson, 1816 using light, fluorescent and transmission electron microscopy. At the onset of spermatogenesis in testes, the pear-shaped spermatogonia divide mitotically without full cytokinesis and as a result isogenic groups are formed (clusters, clones) with 2, 4, 8, 16, 32, 64, 128 spermatogonia and, finally, 256 primary spermatocytes occur. The final meiotic divisions of spermatocytes give rise to clones with 1024 spermatids. There are hundreds of developing germ-line clones in each testis. In each clone, the male germ cells divide in full synchrony and they are in the same phase of spermatogenesis. During complex spermiogenesis each spermatid becomes a filiform spermatozoon with a helicoid nucleus, which is characterized by the presence of a long acrosome with two regions - anterior and posterior, which are followed by a helicoid nucleus, a midpiece with only one mitochondrion and a long flagellum. Our results were compared to those on other clitellate annelids that have been studied to date, especially to sperm formation in Hirudo medicinalis Linnaeus, 1785. Only minor differences were found in the length and the diameter of different organelles and the number of spermatids in germ-line clones.
本文利用光学显微镜、荧光显微镜和透射电子显微镜展示了1816年命名的水蛭Hirudo troctina Johnson的精子发生过程。在睾丸精子发生开始时，梨形精原细胞进行有丝分裂，但胞质分裂不完全，结果形成了同基因群体（簇、克隆），其中有2、4、8、16、32、64、128个精原细胞，最终产生256个初级精母细胞。精母细胞的最终减数分裂产生了含有1024个精子细胞的克隆。每个睾丸中有数百个正在发育的生殖系克隆。在每个克隆中，雄性生殖细胞完全同步分裂，且处于精子发生的同一阶段。在复杂的精子形成过程中，每个精子细胞都会变成一个丝状精子，其具有螺旋状细胞核，其特征是存在一个长顶体，顶体有两个区域——前部和后部，后面跟着一个螺旋状细胞核、一个只有一个线粒体的中段和一条长鞭毛。我们将结果与迄今为止已研究的其他寡毛纲环节动物的结果进行了比较，特别是与1785年命名的医用水蛭Hirudo medicinalis的精子形成结果进行了比较。在不同细胞器的长度和直径以及生殖系克隆中精子细胞的数量方面，仅发现了微小差异。
