中国雨蛙精子形成的研究

SPERMIOGENESIS IN HYLA CHINENSIS

中国雨蛙的精子形成过程中 ,细胞核的浓缩经历了 5个时期。从第 1期进入第 2期 ,染色质纤维增粗并聚集成卷曲的柱状结构。从第 2期进入第 3期 ,染色质纤维进一步增粗 ,细胞核逐渐伸直成柱状。进入第 4期 ,染色质紧密聚集 ,纤维之间间隙很小。进入第 5期 ,染色质纤维聚集成均匀的致密结构。伴随着染色质的浓缩 ,核膜数次更新 ,核内不参与浓缩的物质渐次从核中排出 ,核中出现一串核泡。顶体在染色质未浓缩之前 (第 1期 )开始分化 ,由一巨大的囊泡渐次形成锥状的结构 ,套于细胞核的前端。在顶体下腔之中 ,有一由微管聚集成锥状的顶体下锥。伴随着鞭毛的形成 ,线粒体构成了袖套。在精子细胞趋近成熟之时 ,袖套逐渐退缩 ,线粒体移位 ,环绕于远端中心粒和轴丝的近核端外方。

During the process of spermiogenesis of Hyla chinensis,the nucleus of spermatid changes step by step.According to the morphology of the nucleus and the condensation of the chromatin,the spermatid nucleus can be divided into five stages.During the development from the stage 1to the stage 2,the chromatin fibers became thicker and assembled into a cylindrical structure,which curled within the nuclear envelope.Entering stage 3,the thickness of the chromatin fibers increased further,and the winding cylindrical structure elongated progressively.In the stage 4,the chromatin fibers have gathered tightly and the gaps between them are very small.At the stage 5,the chromatin fibers gathered completely and became evenly dense. Accompanying the condensation of the chromatin,the nuclear envelope replicated several times,and the nuclear material,which was not involved in the chromatin condensation,was abandoned from the nucleus.A row of nuclear vacuoles can be seen in the cylindrical nucleus.The acrosome began to differentiate before the chromatin condensation(Stage 1),which started with a large vesicle.The vesicle formed a conelike acrosome progressively and covered the anterior end of the nucleus.Within the subacrosomal space,microtubules assembled to form subacromal cone.As soon as the formation of early flagellum,mitochondria and cytoplasm constituted a sleeve.As the late spermatid tended towards maturation,the sleeve shrank back,and the mitochondria moved towards the proximal end of the flagellum.They surrounded the distal centriole and proximal end of the axonem.At last,the sleeve disappeared completely.