The Research Of The Gametogenesis Of The Bay Scallop

Gamete and gemetogenesis of the bivalve are researched in interior and overseas, but a prelmiary study on gonad development and ultrastructure of sperm of a subspecie of the bay scallop, however the process of the gemetogenesis and oogenesis of the bay scallop remains unknown up to date. As a kind of main commercial molluscan species, research gemetogenesis of bay scallop not only enrich basic knowledge of developmental biology and cell biology, but also have important significance in regard to develop thorough artificial breed and promote increase in value in natural resources. This article report the gametogenesis of the bay scallop by the way of histology and ultructure.1.SpermatogenesisThe ultrastructurce of spermiogenesis of Argopecten irradians was observed with EM and Light miscope.By observation,we can see that theArgopecten irradians was composed of elctal membrance and many repetitious affiliated male gonadcts. From the external to the internal,the small gonaducts sequently divisived to be spermiogensis, primaryspermatocyte, secondary spermatocyte,and spermatrd. The spermatogoniu is the biggest ,and the chromosome in the nuclear is sparse,nucleolus is only one.The primary spermatocyte is a bit smaller than the spermatogoniu,the chromosome in the nuclear condense,mitochondria is distrbuted in the ambience of the nuclear. The secondary spermatocyte is a little smaller than the primary spermatocyte,and the chromosome condensed to be bigger mass, there is no nucleous. The spermatid is circular shape or ellipse,the chromosome go step further concentration,cell organ is mainly disappear. The mature spermatozoon consists of head ,middle piece and tail ,the acrosome is V-shape in upside-down, the nuclear is egg-shaped with high electron-density. Proximal centrioles,distal centriole and four mitochondras form middle piece of sperm.Microtubular structure limitied by the cell membrane.2.OogenesisThe bay scallop include the external membrane and the reproductive tubule, there are oogenium and primary oocyte in reproductive tubule. On the basis of regular pattern of cell's growth and development, process of vitellogenesis ,the processes can be devided into three stages: reproductive stage,growth stage,mature stage. During the growth stage it can be devided into two stage:early vitellogenesis stage and middle vitellogenesis stage on the basis of number of the nutrition (yolk). In the early vitellogenesis ,cell start accumulating yolk, in the middle vitellogenesis stage ,cell have accumulated large quantity yolk granules, the yolk granules is formed by means of mitochondria, endoplasmic reticulum ,golgibody , lipid,Nuclear membrane vacuole and annulate lamellae.