Morphologic Studies On The Development Of Reproductive Systems And Embryogenesis In Moina Macrocopa

Cladocera, or water fleas, are microscopic crustaceans. Moina macrocopa appear in high concentrations in pools, ponds, lakes, ditches, slow-moving streams and swamps where organic material is decomposing. They become especially abundant in temporary water bodies which provide them with suitable conditions for only a brief period. 17-30℃ is the optimum reproductive temperature of Moina macrocopa which have a better fecundity. Moina macrocopa feed on various groups of bacteria, yeast, phytoplankton and detritus (decaying organic matter). Bacterial and fungal cells rank high in food value. Moina macrocopa is a kind of familiar freshwater cladocera in Shanghai belonging to the genera Moina, the family Moinidae. Moina macrocopa appears in summer, which is different from Daphnia carinata. It is convenient to gather and culture this fleas in the lab condition. In this paper, we chose Moina macrocopa, a common species in fresh water, as the experimental animal.Compared with many large-sized cruscateans, studies on small-sized cladocerans were few. So far, the reports on development and the reproduction of cladocerans were very few. A few papers were focused on the spermatogenesis and oogenesis of some species in last century. Recently, many researches have been concerntrated on mechanism of reproductive conversion, while embryogenesis and germ cell genesis are precondition of all the works. Under the background, we hope that morphological study on Moina macrocopa may have both practical and theoretic values.In this paper, methords of histology and electron microscope were used to describe oogenesis and spermatogenesis of Moina macrocopa. We made a preliminary study on the histology of gamogenetic egg, observed external morphological changes of embryogenesis and microstructure of embryos, measured digestive enzyme activities and the contents of protein during embryonic development of Moina macrocopa. The morphological changes were also described in detail in the process of post-embryonic development and larval development. The results and conclusions were listed as following:1. Oogenesis in parthenogonidium of Moina macrocopa Straus (Crustacea, Diplostraca)The features of oogenesis in parthenogenetic Moina macrocopa were observed...