1-Methyladenine-producing cell in starfish testis☆

Abstract The site of production of 1-methyladenine (1-MeAde) in the testis of the starfish, Asterina pectinifera , was investigated. Incubation of spermatozoa with the gonad-stimulating substance (GSS) revealed that spermatozoa do not have any 1-MeAde-producing activity. After removing most of the spermatozoa, the testis components were divided into testicular wall fraction and free cell fraction. When their 1-MeAde-producing activity was compared, the free cell fraction showed higher activity than the wall fraction. The free cell fraction contained mainly two types of cells: A cells, 7–10 μm in diameter and with granular cytoplasm, and B cells, 4–5 μm and with clear cytoplasm. The purified A cell fraction was found to produce 1-MeAde under the influence of GSS, whereas the B cell fraction failed to produce the substance. It is therefore concluded that the site of production of 1-MeAde in starfish testes is the A cell. Electron microscopic observation of A-cells revealed that these 1-MeAde-producing cells are non-germinal and phagocytotic, and are located along the germinal epithelium of the testis. They are also found among the developing germ cells and spermatozoa in the center of the testis.