胎儿端脑突触素表达和突触发育的研究

STUDY ON THE EXPRESSION OF SYNAPTOPHYSIN AND THE DEVELOPMENT OF SYNAPSE IN THE TELENCEPHALON OF HUMAN FETUS

为了探讨突触素(SYN)在不同周龄阶段胎儿端脑额叶中的表达与胎儿额叶皮质突触发育的关系,本研究采用免疫组织化学方法观察突触素在不同周龄阶段胎儿额叶的表达水平,利用计算机图像分析技术测量不同周龄阶段胎儿额叶突触素表达的平均光密度;同时取材、常规电镜技术处理、透射电镜观察额叶突触发育的超微结构变化。结果显示:(1)光镜下各组均可见SYN免疫阳性产物主要表达于胎儿的额叶皮层,其表达量随周龄的增加而增强,各组间呈现显著性差异(P<0.05),其中16～24周胎儿额叶的阳性产物位于神经元的胞浆内,呈均匀的浅黄色,神经元突起内未见阳性产物;25～29周额叶的阳性产物呈黄色,在胞浆和突起内均可见,但阳性产物的量却下降;而30～39周额叶的SYN阳性产物呈棕黄色的点状或颗粒状,主要位于神经元的突起内,神经元胞浆内未见阳性产物,阳性产物的量显著增加;(2)透射电镜下19～36周胎儿大脑额叶均可见到突触样结构,随着周龄的增加,突触的数量逐渐增多,结构逐渐清晰和完整。上述结果提示SYN的表达可以反映胎儿神经系统发育的程度,SYN的表达与突触的发育是一致的;SYN在胎儿大脑额叶的表达部位经历由神经元胞浆内表达为主到神经元终末表达为主的这一过程,可能是由于SYN先是在神经元胞浆内合成,再随着神经元的发育而逐步转移到神经元突起的末梢部位。

To investigate the relationship between the expression of synaptophysin （SYN） and the development of synapse in the frontal lobe of different periods of human fetus, this study tried to observe the expression of SYN in frontal lobe at different periods of human fetus by immunohistochemical technique. Computer image analysis system was used to measure the average optical density of SYN in the frontal lobe of different stages of human fetus, meanwhile, the uhrastructural change of synaptic development in the frontal lobes was observed by electron microscope, The results showed that： （1） Under light microscope, the SYN immunoreactive （SYN-IR） products were expressed in the inferior frontal lobe of human fetus in each group. With the age increasing, the SYN-IR products also increased obviously, and there was statistic significantly between different groups （P 〈0.05 ）. Among the 16- 24 weeks group, the SYN-IR products only located in cytoplasm with the color of pale yellow, but no positive products were found in the neurite. For 25 - 29 weeks group the stained yellow positive products could be seen in both the cytoplasm and the neurite with the lowered quantity. For 30 -39 weeks group, the SYN positive products appeared in the form of fine brown grannies and mainly located around the neurite. No positive products were found within the cytoplasm of neurons and the total quantity of positive products increased significantly; （2） Under the transmission electron microscope, the synapse-like structure could be seen in the frontal lobe of 19 -36 weeks old human fetus, The older the age, the more was in the number of the synapse and the more was clear and complete of the structure. The above results suggest that the expression of SYN can reflect the developing degree of the human fetal nervous system and it is synchronous with the development of the synapse. The shifting position of SYN of frontal lobe from the cytoplasm to the terminal may indicate that the SYN may be compounded in the neuronal cytoplasm and then transported to the end of neurite steadily with the development of the neurons.