Ultrastructural evidence for the existence of steroid synthesizing cells in the ovary of the starfish. Asterias rubens (echinodermata).

The ultrastructure of cells showing characteristic features of steroid producing cells in the ovaries of the starfish. Asterias rubens, is described. The correlation between the appearance of these cells and steroid biosynthesis in ovarian tissue of A. rubens is discussed. The importance of the discovery of these cells in view of the biosynthesis of steroids and the phylogeny of Echinodermata is mentioned.