生长抑素样神经元及其纤维在人胎下丘脑的分布与发育研究

本文用免疫细胞化学技术观察了人胎下丘脑内含生长抑素样神经元及其纤维的分布与发育。胎龄14周,见浅染的生长抑素免疫反应阳性神经元散布于下丘脑前部、室周带、第三脑室壁室管膜上皮深面。15～16周胎龄,含生长抑素样神经元除见于上述部位外,还见于腹内侧基底部、室旁核、视上核和室管膜上皮内,阳性纤维散布于正中隆起,室管膜上皮。17—18周胎龄,含生长抑素样结构在上述部位变化明显,神经元更加密集,分布范围扩大,反应染色加深,阳性突起延长。21周胎龄至足月胎儿,含生长抑素神经元及其纤维在下丘脑的分布变化不明显。生长抑素样神经元以中、小型细胞为主,室旁核内见有少量大细胞。电镜观察21周和29周胎龄正中隆起发现:毛细血管为窗孔型,基底膜外有生长抑素样阳性终末靠近。在阳性终末及非阳性终末内可见分泌囊泡。本结果提示人下丘脑内生长抑素系统在出生前已经发育并可能参与内分泌活动的调节。

A STUDY OF THE DISTRIBUTION AND DEVELOPMENT OF SOMATOSTATINLIKE NEURONS AND FIBERS IN HYPOTHALAMUS OF HUMAN FETUS

The research of the ontogeny of somatostatin-like neuron system in hypothalamus was carried out on three newborn infants and 25 fetuses ranging from 14-34 weeks. The immunocytochemical staining, PAP method, was employed. The results show that SRIF positive neurons were scattered in the anterior hypothalamus, periventricular zone and were deep in the third ventricular floor in the 14 week of fetal life. In 15-16 weeks, SRIF positive neurons were also found in mediobasal area, PVN, SON and in the thickened ependyma, SRIF positive fibers were discovered in the median eminence and ependyma, In 17-18 weeks, a fast increase in number of SRIF positive neurons and darker immunoreactive staining were noticed. In 21 week to newborn, there were no obvious change of SRIF positive neurons both in number and staining. Most SRIF positive neurons were small or medium sized, but a few large cells were observed in PVN. The findings in the median eminence (ME)of 21 week and 29 week by electron microscopy were (1) there were pores or fenestrae on the capillary endothelium in ME. (2) SRIF positive nerve endings were close to the basal membrane of the capillaries. (3) Secretory vesicles were observed in SRIF positive and negative endings.The observations provide evidence supporting that somatostatin system in human hypothalamus has been developed and has begun its functional roles before birth.