Three-dimensional analysis for neural network of photosensory pineal organ

在日本七鳃鳗的松果体中，有两种类型的松果体光感受器，典型的和改良的，分别被认为是视网膜中的纯感光细胞样视细胞和分泌褪黑素的光神经内分泌细胞。我们用荧光标记技术和激光共聚焦扫描显微镜对松果体感光细胞和神经节细胞及其神经网络的结构和亚型进行了三维研究。研究结果总结如下：1.显示5-羟色胺免疫反应的光神经内分泌细胞具有一个基本突起，该突起似乎不会分支。这些突起在末端小泡的基底部相互接触，2.大部分5-羟色胺免疫反应细胞呈碘五肽免疫反应阳性，但不是全部。这些结果表明，在松果体器官的末端囊泡中，碘蛋白免疫反应阳性细胞作为神经内分泌细胞占主导地位。一些视黄素(视锥细胞特异的钙结合蛋白)免疫反应细胞不显示碘视黄素免疫反应。许多Visinin免疫反应细胞呈视紫红质免疫反应。这些结果表明，松果体复合体中除Ioopsin免疫反应细胞外，还存在另一种锥体型感光细胞。球状和大的神经节细胞主要分布在末端小泡的周边区。与Visinin免疫反应阳性细胞相连的神经节细胞呈球形，体积较大。

In the pineal organ of river lamprey, Lampetra japonica, there are two types pineal photoreccptors, typical and modified, which are regarded as the pure photoreceptor cell like visual cells in retina and the photoneuroendocrine cell secreting the melatonin, respectively. We investigate for the structure and the subtype of pineal photoreceptors and ganglion cells and their neural network three-dimensionally by use of a fluorescent labeling technique and a confocal laser-scanning microscope. The results are summarized below.1. The photoneuroendocrine cell, which shows serotonin immunoreactivity, possesses a basal process, and it appears that the process does not branch out. These processes contact each other at the basal region of the end vesicle, .2. Most of serotonin-immunoreactive cells showed iodopsin immunoreactivity, but not all. The results suggest that the iodopsin (red-cone visual pigment)-immunoreactive cells are predominant in the end-vesicle of lamprey pineal organ as neuroendocrine cells.3. Some visinin (cone-specific Ca2+binding protein)-immunoreactive cells show no iodopsin immunoreactivity. Many visinin-immunoreactive cells showed rhodopsin immunoreactivity. The results suggest that another cone-type photoreceptor exits in the pineal complex besides iodopsin immunoreactive cells.4. Globular and large ganglion cells were mainly located at peripheral region of the end vesicle. The ganglion cells connecting with the visinin-immunoreactive cells were globular in shape and large in size.