移植视网膜酪氨酸羟化酶免疫反应神经元的发育

DEVELOPMENT OF NEURONS EXHIBITING TYROSINE HYDROXYLASE IMMUNOREACTIVITY IN TRANSPLANTED RETINAS IN RATS

将妊娠１４ｄＳＤ大鼠胚胎视网膜移植至新生大鼠之中脑，应用免疫细胞化学方法，观察了术后１０～３４ｄ的移植视网膜和正常视网膜的酪氨酸羟化酶免疫反应（Ｔｙｒｏｓｉｎｅｈｙｄｒｏｘｙｌａｓｅｉｍｍｕｎｏｒｅａｃｔｉｖｉｔｙ，ＴＨ—ＩＲ）神经元的出现时间、定位分布及其发育过程。结果表明，移植视网膜生长正常，具有与同龄正常视网膜极为相似的结构，ＴＨ—ＩＲ神经元的形态和定位分布与正常视网膜相一致。术后１０ｄ（当于正常大鼠出生当日）的移植视网膜ＴＨ—ＩＲ神经元见于成神经细胞层，生后４ｄ见于节细胞层；６～８ｄ以后位于内核层和节细胞层；至１２ｄ，ＴＨ－ＩＲ阳性细胞数达到高峰，平均９～１０个／ｍｍ２，以后有所下降，逐渐接近正常。按细胞形态特点分为两型，Ⅰ型细胞胞体大，直径１１～２０μｍ，树突较多而粗；Ⅱ型细胞胞体小，直径５～１０μｍ，树突较少。它们的突起分支进入内网层并弥散分布，常见密集于第１亚层，有时见于第１和第３亚层。上述结果提示：移植视网膜和正常视网膜ＴＨ—ＩＲ神经元是无长突细胞，其发育过程与正常视网膜极为相似。这为研究移植视网膜神经元的发育规律，以及神经系统的可塑性和再生，提供有意义的资料。

Fourteenth day embryos retinas from Sprague-Dawley rat were transplanted to the midbrain of newborn recipient rats. The distribution, appearing time and development of neurons exhibiting tyrosine hydroxylase immunoreactivity (TH- IR) in the retina of normal and transplanted rats from 10 to 34th day after transplantation were observed by immunocytochemistry. The results showed that transplanted retina could survive and differentiate continuously. The morphology and the localization of TH - IR neurons were the same of the transplanted and normal retina of the corresponding ages. In the 10th day after transplantation (corresponding of postnatal day 0, P0), the somata of TH-IR neurons in the transplanted retina were located in the neuroblastic layer and then appeared in the ganglion cell layer (GCL) by the P4,from P6 to P8 it was seen in inner neuclear layer (INL) and the GCL. By the postnatal day 12, the numbers of TH - IR cells were in the highest peak, mean value attained to 9-10 cells/mm2. After the peak stage, the number was decreased slightly to the same level as that in the normal rats. TH-IR neurons were of two morphological types: Somata of type ⅠTH-IR cells were larger in size and varied from 11 to 20 μm in diameter, Somata of type Ⅱ cells were smaller and varied from 5 to 10 μm. These cells sent their processes to the inner plexiform layer (IPL) and ramified in the sublayer 1 and 3. These results suggested that TH- IR neurons in the transplanted retina were amacrine cells. The developing procedure of TH-IR neurons in transplanted retina is largely similar to that in normal retina.