南方鲇垂体的超微结构

Ultrastructure of Pituitary in Silurus meridionalis

应用透射电镜技术,对产卵前、后性成熟野生雌性南方鲇垂体的超微结构进行研究.结果表明:南方鲇垂体呈背腹型,由神经垂体和腺垂体两部分组成.神经垂体具A1、A2和B型神经分泌纤维以及两种类型的脑垂体细胞.腺垂体观察到了8种类型分泌细胞即:促肾上腺皮质激素(ACTH)细胞、催乳激素(PRL)细胞、生长激素(GH1、GH2)细胞、促性腺激素(GTH)细胞、促甲状腺激素(TSH)细胞、黑色素细胞刺激激素(MSH)细胞和首次在鱼类报道的大型泡状细胞.产卵前、后ACTH细胞超微结构变化明显,参与促进卵母细胞的最后成熟和排卵活动;GTH细胞产卵前、后均存在激素合成和分泌等不同的生理状态,与卵母细胞的发育、成熟和排卵有关;首次在南方鲇观察到了两种超微结构差异明显的GH细胞,具有不同的生理功能,GH1细胞与卵母细胞的成熟及排卵有关,GH2细胞与生长有关.SL细胞由于数量少,未在垂体中间部观察到.

The ultrastructure of pituitary in wild adult female Silurus meridionalis was studied in prespawning and post-spawning with transmission electron microscopy. The results indicated that pituitary in S. meridionalis is of the dorsoventral type, which consists of neurohypophsis and adenohypophysis. Three types of neurosecretory fibres （A1, A2 and B） and two of pituicytes were recognized in the neurohy- pophysial tissue. Eight types of secretory hormone cells were observed in adenohypophysis, namely, lac- totropes, corticotropes, gonadotropes , two types of somatotropes, thyrotropes, melanotropes and the big froth cells reported in fish pituitary for the first time. Great changes of the ultrastructure of corticotropes and gonadotropes were observed in both pre-spaw- ning and post-spawning, indicating that they are associated with the maturity of ooeytes and ovulation. Producing and releasing hormone gonadotropes were found to be present in pre-spawning and post- spawning, which showed that they are associated with development and maturity of oocytes and ovulation. Two distinct somatotropes were noticed for the first time in the pituitary of adult S. meridionalis, and they seemed to play different roles. GH1 cells were associated with maturity of oocytes and ovulation, while GH2 cells were associated with growth. Somatolactin cells were not observed in pars intermadia due to their scarcity.