Innervatiuon of steroid-producing cells in the gonads of fish.

用免疫组织化学和超微结构观察了尼罗罗非鱼性腺的神经分布。在睾丸中，许多粗大的神经束分布在传出管周围的壁上。这些神经元似乎终止于传出管壁的平滑肌细胞表面。细神经束穿透含有生精生殖细胞包囊的小叶之间的间隙。这些神经纤维的末端还与包围小叶的平滑肌细胞和类固醇产生细胞的表面接触。这些观察表明，睾丸的神经支配不仅可以控制平滑肌细胞的收缩和松弛，还可以控制类固醇的分泌。在卵巢内，粗大的神经束位于靠近卵巢动、静脉的部位，位于卵巢壁面系膜一侧。从粗大的神经中分出几组轴突，终止于类固醇产生细胞簇的附近，这些类固醇产生细胞分布在卵黄卵母细胞之间的间质区域。轴突终末与类固醇分泌细胞关系密切。终末含有许多透明的小泡、少数致密的核心小泡和一些线粒体。此外，在卵黄卵母细胞周围的类固醇分泌的膜细胞表面也观察到少量的终末。我们对类固醇产生细胞的直接神经支配的观察揭示了调控罗非鱼卵巢类固醇产生的一种可能的新途径。

The innervation of the gonads of Oreochromis niloticus examined immunohistochemically and ultrastructurally. In testis, many thick nerve bundles are distributed in the wall surrounding the efferent duct. The neurons appear to terminate at the surface of smooth muscle cells in the efferent duct wall. Thin nerve bundles penetrate the interstices among lobules containing cysts of spermatogenic germ cells. terminal ends of these nerve fibers also make contact with smooth muscle cells enclosing lobules and with the surface of steroid-producing cells. These observations suggest that innervation of the testis may not only control the contracting and relaxing of smooth muscle cells but also control steroid secretion. In ovary, thick nerve bundles were localized in the area near the ovarian artery and vein in the ovarian wall on the side facing the mesentery. Groups of a few axons ramified from the thick nerves and were terminated in the proximity of clusters of steroid-producing cells which are distributed in the interstitial area among yolky oocytes. The axon terminals were in intimate relation with the steroid-producing cells. The terminals contained many clear vesicles, a few dense-cored vesicles and some mitochondria. Moreover, a few terminals were observed on the surface of steroid-producing theca cells surrounding yolky oocytes. Our observations of direct innervation of steroid-producing cells bring to light a possible new avenue for regulation of steroid production in the tilapia ovary.