Tanimura A, Iwasawa H
Biological Institute, Faculty of Science, Niigata University, Japan.
Anat Embryol (Berl). 1989;180(2):165-73. doi: 10.1007/BF00309768.
Gonadal development in Rhacophorus arboreus, a sexually semidifferentiated type of tree frog, was observed by means of the electron microscope, and cell proliferation kinetics were examined autoradiographically. The genital ridge consisted of coelomic epithelial cells and primordial germ cells. The gonadal medulla was formed by the segregation of epithelial cells within the primordial gonad. Thereafter, the medullary cell mass was well developed and oogenesis began in the gonadal cortex, irrespective of genetic sex. During metamorphosis, the ovarian cavity was formed in the medullary mass. This ovarian structure developed further in females. In males, on the other hand, a layer of medullary cells comprising the epithelium of the ovarian cavity proliferated rapidly and reformed a large cell mass. The degeneration of ovarian follicles and the formation of cell cords (rudimentary seminiferous tubules) were seen in the cortex. These cell cords were separated from the superficial epithelium and continued to the medullary mass (rudimentary testicular rete). These results clearly indicate that both the cortical and medullary cells are derived from the coelomic epithelium and that the development of the cortex and medulla is not always antagonistic in the course of sexual differentiation.
利用电子显微镜观察了半性分化型树蛙——斑腿泛树蛙的性腺发育，并通过放射自显影术检测了细胞增殖动力学。生殖嵴由体腔上皮细胞和原始生殖细胞组成。性腺髓质由原始性腺内上皮细胞的分离形成。此后，髓质细胞团发育良好，性腺皮质开始卵子发生，与遗传性别无关。在变态过程中，髓质团中形成卵巢腔。这种卵巢结构在雌性中进一步发育。另一方面，在雄性中，构成卵巢腔上皮的一层髓质细胞迅速增殖，重新形成一个大的细胞团。在皮质中可见卵泡退化和细胞索（初级生精小管）形成。这些细胞索与表面上皮分离，并延伸至髓质团（初级睾丸网）。这些结果清楚地表明，皮质和髓质细胞均来源于体腔上皮，并且在性别分化过程中，皮质和髓质的发育并不总是相互拮抗的。
