人胚胎视网膜5—羟色胺样免疫反应神经元的发育

本文应用免疫细胞化学技术研究了妊娠第8周至第28周人胚胎视网膜5—羟色胺样免疫反应(5—Hydroxytryptamine like immunoreac-tion,5—HT—LI)神经元的定位和发育,观察了切片和平铺片共40例。结果表明,第10周人胚胎视网膜开始出现5—HT—LI神经元,它们分散在内成神经细胞层,胞体圆形,卵圆形,直径6—7μm。人胎第11至第13周5—HT—LI神经元数量增加,细胞大小比较一致,并处于迁移之中;此时约49.5%的5—HT—LI细胞位于节细胞层,其余位于节细胞层以外。第17至第18周位于节细胞层的5—HT—LI细胞达88.5%,位于内核层约11.5%;其中位于内核层最内缘的细胞约7.3%,这些细胞大致可分为大、中、小3型,其直径分别是8—10μm,6—7μm,和5—6μm,每平方毫米细胞数为8.1±2.19细胞(平均数±标准差)。第21周时为10.7±2.16细胞/mm~2。第14周以前可见5—HT—LI纤维分布在神经纤维层,自此之后,未见5—HT—LI纤维存在,上述结果提示,5—HT—LI神经元是发育中的无长突细胞,这些细胞在第10周人胎视网膜出现,至第17至18周已发育到相当阶段,但未见细胞间的纤维联系,此后神经元继续发育至成熟。

DEVELOPMENT OF 5—HYDROXYTRYPTAMINE LIKE IMMUNOREACTIVE NEURONS IN RETINA OF HUMAN FETUS

Immunocytochemical technique was used to explore the location and development of 5—hydrox- ytryptamine like immunoreactive(5—HT—LI)neurons in retina of human fetus the 8th to 28th week of pregnancy.The sections and flat mounts of 40 cases have been observed.The results show that 5—HT—LI neurons begin to appear in fetal retina in the 10th week and they dispersed in inner nu- clear layer with a round or oval shape of 6—7 μm diameter.5—HT—LI neurons increase in num- ber,become uniform in size,and are in a migrating state during the 11—13th week;at this time 49.5% of the neurons are found in the ganglion cell layer and the rest is out of this layer.In the 16—17th week,5—HT—LI neurons in the ganglion cell layer increase up to 88.5%,11.5% are in the inner nuclear layer,and 7.3% are in the most inner nuclear layer,These neurons are found in three types:large,medium,and small in sizes with diameter of 8—10μm,6—7μm and 5—6μm re- spectively.The cell number is 8.1±2.19/mm~2(mean±SD)in the 17—18th week and 10.74±2.16/ mm~2 in the 21th week.Before the 14th week,there are 5—HT—LI terminals found in the nerve fiber layer,but they disappar afterwards.This result suggests that the 5—HT—LI cells are amacrine cells which appear in retina at the 10th week,continue to develop considerably in the 17—18th week,but no intercellular connections in this period.Thereafter,these neurons continue to develop into the mature stage.