蟹类精荚贮存和裂解研究进展

甲壳动物在海洋中分布广泛，有多种精子传输方式，大部分产生精荚，粘于雌体腹部或通过交接器输送到纳精囊中。研究表明，在蟹类交配，精子转移，贮存和受精等过程中，存在如精子竞争和亲体保护，多次受精等众多复杂事件。这些过程主要是以蟹类纳精囊为核心异型，为此本文综述了纳精囊的结构和功能，精子活力的维持，精荚形态，精子竞争和转移等近年研究进展，旨为相关研究提供参考。

Study on spermatophore storage and dehiscence in crab

In general,crab receives copious quantities of seminal fluid during mating,and stores them in special seminal receptacles,viz.spermatheca,for a prolonged period.The spermatheca of the advanced brachyuran crabs has been described for many species.The spermatheca is a dilation of the proximal region of the oviduct connecting it to the ovary.The vagina leads from the base of the spermatheca and opens outside the ovipore.Some crabs have the special structure,such as valve-like tissue,bursa,intermediate chamber.The seminal secretion delivered during mating has been shown to undergo a kind of solidification inside the spermatheca,giving rise to a structure called "sperm plug".In some species the sperm plug extends into the vagina and even protrudes from the vulva.The role of a sperm plug is not certain,but it has been assumed that it helps to prevent the loss of sperm after copulation.The sperm viability during prolonged storage is an interesting question,the seminal substances,together with spermathecal secretions,could provide nutrients and antibacterial substance for sperm maintenance.The anaerobic environment of spermatheca and the unmature spermatozoa for storage are also the reason for survival in spermatheca.In brachyuran crabs where multiple mating occurs,there is sperm competition for fertilization.Some study revealed the existence of another type spermatophore with smooth and thin spermatophoric walls,so differences in the morphology of the spermatophoric wall were directly related to the degree of dehiscence of spermatophores upon copulation,which supports the hypothesis of different fertilization.So the quantity of ejaculate stored in spermathecae does not necessarily correlate with the mating success of the female,but may also depend on the type of spematophores and their quantity transferred at the previous mating.In the brachyura,sperm transfer and storage mechanisms are related to the type of fertilization.Whether is internal or external needs more research on the fertilization of egg in spermathecae..