Viana Ivana Kerly S, S Gicelle M F, Pantoja Juliana C D, Oliveira Renata S, Mendes Yanne A, Nunes José Leocyvan G, Ferreira Maria Auxiliadora P, Rocha Rossineide M
Laboratory of Cellular Ultrastructure, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, 66075-110, Brazil.
Laboratory of Immunohistochemistry and Developmental Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, 66075-110, Brazil.
BMC Zool. 2022 Jan 4;7(1):3. doi: 10.1186/s40850-021-00106-5.
Hypostominae is a subfamily of the family Loricariidae that has a great diversity of species. Accordingly, testicular studies in fish can contribute to the phylogeny and taxonomy of species and to the comparison of reproductive aspects between species. Thus, this work aimed to characterize the testicular morphology and spermatogenesis of the Hypostominae species Baryancistrus xanthellus, Peckoltia oligospila and Hypancistrus zebra.
B. xanthellus, P. oligospila and H. zebra had an anastomosed tubular type of testis. The germinal epithelium was continuous with unrestricted spermatogonia, and the proliferative, meiotic and spermiogenic phases were defined in all species. In the spermiogenic phase, spermatids were classified as initial, intermediate and final. Only in B. xanthellus in the final phase was there nuclear rotation. The sperm for the three species had a head with an oval shape and a single flagellum composed of the short midpiece, principal piece and end piece. B. xanthellus and P. oligospila showed a cylindrical flagellum and H. zebra showed projections that produced a flattened appearance.
On the basis testicular structure and ultrastructural characteristics of the germ cells, there was a greater relationship between B. xanthelus and P. oligospila, while H. zebra had particular characteristics. These aspects show that despite belonging to the same subfamily, the species have distinct biological characteristics.
下口鲶亚科是骨甲鲶科的一个亚科，物种多样性极高。因此，对鱼类睾丸的研究有助于物种的系统发育和分类，以及物种间生殖方面的比较。因此，本研究旨在描述下口鲶亚科物种黄斑下口鲶、少棘琵琶鼠鱼和斑马下口鲶的睾丸形态和精子发生过程。
黄斑下口鲶、少棘琵琶鼠鱼和斑马下口鲶具有吻合管状睾丸。生殖上皮与无限制的精原细胞连续，所有物种均定义了增殖期、减数分裂期和精子形成期。在精子形成期，精子细胞被分为初始、中间和终末阶段。仅在黄斑下口鲶的终末阶段存在核旋转。这三种物种的精子头部呈椭圆形，有一条由短中段、主段和末段组成的单一鞭毛。黄斑下口鲶和少棘琵琶鼠鱼的鞭毛呈圆柱形，斑马下口鲶的鞭毛有突起，使其外观扁平。
基于睾丸结构和生殖细胞的超微结构特征，黄斑下口鲶和少棘琵琶鼠鱼之间的关系更为密切，而斑马下口鲶具有独特的特征。这些方面表明，尽管属于同一亚科，但这些物种具有不同的生物学特征。
