长吻鮠不同时期脑垂体的超微结构

采用组织学方法和透射电镜技术对性周期内不同阶段和不同季节的雌性长吻鮠(Leiocassis longirostris)脑垂体的超微结构进行较详细的研究，结果表明：长吻鮠脑垂体包括腺垂体和神经垂体两个部分，腺垂体组织中有6种分泌细胞，即促性腺激素(GTH)分泌细胞、生长激素(STH)分泌细胞、促甲状腺激素(TSH)分泌细胞、促黑色素细胞刺激激素(MSH)分泌细胞、催乳激素(PRL)分泌细胞、促肾上腺皮质激素(ACTH)分泌细胞。神经垂体组织中存在A型(A1、T2)和B型神经分泌纤维，A型分泌纤维轴突中具有不同类型的分泌颗粒，B型分泌纤维轴突中含有许多透明小囊泡。产卵前GTH细胞胞质中充满了电子密度较高的大、小两种分泌颗粒；TSH细胞胞质中分泌颗粒排空，电子密度降低，出现大空泡；STH细胞处于活跃的合成和分泌状态；MSH细胞粗面内质网相当发达，成层围核分布，分泌颗粒极少；PRL细胞电子密度高，具圆球形被膜的分泌颗粒；ACTH细胞分泌物颗粒数量少。产卵后GTH细胞中的分泌颗粒排空；TSH细胞出现空泡；STH细胞中的粗面内质网围核环状排列；MSH细胞分泌颗粒多但比较小，粗面内质网呈扁状或网状；PRL细胞分泌颗粒极少，分布不均匀；ACTH细胞内质网近核分布。秋季GTH细胞中发现GTH1和GTH2两种细胞，GTH1细胞具有大量围核分布的分泌颗粒，GTH2细胞胞质中分泌颗粒数量较少；STH细胞胞质中粗面内质网极发达，围核分布，线粒体数量增加；TSH细胞内质网膨大成泡状；MSH细胞有明显的双核结构，其中一核具核仁，胞质内分泌颗粒较产后增多；PRL细胞具有呈不均匀分布的圆球形分泌颗粒；ACTH细胞线粒体与内质网围核分布，分泌颗粒较少，不均匀分布于细胞质中。冬季GTH细胞内有少量分泌颗粒散布在核周围；TSH细胞含有较多的小型分泌颗粒，胞核外周有大量长条形的粗面内质网；STH细胞中分泌颗粒数量较少，合成和分泌活动微弱；MSH细胞粗面内质网呈泡化状，绕核排列；PRL细胞、ACTH细胞和秋季时的超微结构无明显差异。神经垂体中的分泌纤维各阶段也有一定的变化，产前阶段具有较多球形的无被膜分泌颗粒，产后阶段分泌颗粒呈现排空，秋季部分可见到分泌颗粒，但数量相对较少，冬季变化不明显。

Ultra-structure of pituitary in different periods of long-snout catfish

With the method of histological section and electronic microscope, the ultra-structure in different periods of pituitary of female long-snout catfish(Leiocassis longirostris) were studied at different development stages and physiological conditions. The results were as follows.The pituitary of long-snout catfish has adenohypophysis and neurohypophysis. The adenohypophysis have six cell types, i.e,gonadotrophs(GTH), thyrotrophs(TSH), somatotrophs(STH), melanotroph (MSH),lactotrophs(PRL) and adrenocorticotrophs(ACTH) cells. In neurohypophysis, there are three types of neurosecretory fibres, types A_(1), A_(2) and B. There are different types' granules in type A neurosecretory fibres axone. In type B neurosecretory fibres axone, there are many small transparent vesicles.Before spawning, GTH cytoplast are full of high density electron secretory granules,big and small. TSH cells cytoplast evacuate secretory granules; electron density decreases and large vacuoles appeare. STH cells are in activitive synthesis and secretion. MSH cells have few secretory granules, of which the quite developed oplasmic reticulums distribute around nucleus. The electric density of PRL cells with secretory granules is high. There are a few secretory granules in ACTH cells. After spawning, GTH cells evacuate secretory granules. Vacuoles appeare in TSH cells. Rough endoplasmic reticulum in STH cells are circumnuclear. Secretory granules are more but small, in MSH cells, rough endoplasmic reticulum is flat or reticulate. Few secretory granules in PRL cells distribute inequably. In ACTH cells endoplasmic reticulum distribute near nucleus. In autumn, there are GTH_(1)cells and GTH_(2) cells in GTH cells. More secretory granules distribute around nucleus in GTH_(1)cells, and less in GTH_(2) cells. Rough endoplasmic reticulum around nucleus in STH cells is very developed. Its mitochondrias increase. Endoplasmic reticulum in TSH cells expands to froth. There are apparent diploid nucleus in MSH cells. There is a nucleolus in one of nucleus. Secretory granules in cytoplast increase mere than in the period of post-spawn. Circle secretory granules in PRL cells distribute inequably. Mitochondria and endoplasmic reticulum in ACTH cells distribute around nucleus, less secretory granules in cytoplast distributing inequably. In winter, there is a small number of secretory granules scattering around nucleolus in GTH cells. There are more minitype secretory granules in TSH cells, andmany long rough endoplasmic reticulum in nucleus periphery. The numbers of secretory granules in STH cells is relatively small. The activity of synthesis and secretion decreases. The spumescent rough endoplasmic reticulum in MSH cells ranks around nucleus. The ultra-structure of ACTH and PRL cells hare no obvious changes from autumn.During all stages, the neurosecretory fibres in eurohypophysis shows some varieties. There are global and no envelopes secretory granules before propagation. It evacuates secretory granules after propagation. Secretory granules can be seen in some of it in autumn, but the number is relatively small. In winter, it has no apparent changes.