中华绒螯蟹窦腺的显微和超微结构

MICROSTRUCTURE AND ULTRASTRUCTURE OF THE SINUS GLAND IN THE EYESTALK OF ERIOCHEIR SINENSIS

借助光学和电子显微镜观察了养殖河蟹 1龄蟹种、早熟蟹种和 2龄成蟹窦腺的形态结构和神经分泌物质释放方式。河蟹窦腺位于眼柄视神经节内髓与终髓交界处背侧 ,活体为乳白色 ,扁球状 ,大小约为 0 5 5mm×0 45mm× 0 2 3mm。窦腺呈囊状 ,腺体壁由膨大的神经分泌细胞末梢和胶质细胞组成 ,神经末梢内充满电子致密的分泌颗粒。根据颗粒的大小、形态和电子致密度等特征 ,区分出 6种不同类型的神经分泌末梢。河蟹窦腺中的神经分泌物质以胞吐作用方式释放 ,一些现象表明 ,神经胶质细胞参与神经分泌颗粒的释放。 1龄蟹种、早熟蟹种和 2龄成蟹窦腺的形态、结构无明显差异 ,但神经激素颗粒释放情况明显不同 ,从形态结构上证实了窦腺对养殖河蟹性腺发育的调控作用。

Cultured larvae, matured and precocious matured Chinese mitten crab ( Eriocheir sineasis ) were obtained from Renfeng farming Co. in Tianjin, kept in recirculated tap water. The sinus glands (SG) were dissected under ice chilled saline at the transition of the medulla interna and medulla terminalia dorso laterally in the eyestalks of the specimens of the three kinds of crabs (2 1～2 3cm, 3 8～4 3, 5 1～5 4cm carapace width of larvae, matured and precocious matured crabs). For a light microscopic overview, SGs were fixed in Bouin fluid and Chrome hematoxylin staining was performed. For fine structural analysis, SGs were immediately fixed in the 4% Glutaraldehyde in 0 7mol/L sucrose and 5mmol/L CaCl 2 for 3～4 h, followed by postfixation in 1% osmic acid in 0 45mol/L sucrose and 5mmol/L CaCl 2 for 1 5h. After dehydration and embedment, ultrathin sections were cut on a LKB Ultrotome V and examined with Philips EM400ST electron microscopic. Our results suggest that the SG of the Chinese mitten crab is a roughly ellipsoid structure which is mainly composed of enlarged axon terminals abutting on the thin basal lamina of a central hemolymph lacuna acting as a storage release centre for the membrane bound neurosecretory material. Also present in the SG are glial cells with cytoplasmic processes which enwrap the terminals. Six types of neurosecretary terminals were distinguished on the basis of size, morphology and electron density of the neurosecretory granules. Each axon terminal contained 1 type of granule despite of type Ⅴ. The mean granule diameter ranged from 97nm(type Ⅳ) to 258nm(type Ⅰ). Type 3 and type 6 axon terminals were, respectively, the most and least frequent. Neurosecretory granules exocytosis from the terminals were observed in the sinus gland of the Chinese mitten crab. Large multilamellate bodes appeared in terminals depleted of neurosecretory granules and maybe involved in the recycling of granules membrane. Some images showed that glial cells were involved in neurosecretion. The comparison between larvae and matured or precocious matured crabs was demonstrated.