Testicular feminization in the mouse: studies of Leydig cell structure and function

Abstract

The testes of mice with testicular feminization (tfm/y) are small (10% of normal), cryptorchid, and composed of immature tubular elements surrounded by several layers of peritubular cells and enlarged Leydig cells. Morphometric analyses indicated a normal or slightly reduced number of Leydig cells per tfm/y testis. Electron microscopy revealed that these cells have smooth surfaces devoid of microvilli and contain increased quantities of lipid and mitochondria but relatively little endoplasmic reticulum (SER). Mitochondria occupied the major volume of the cytoplasm. These regularly round organelles with tubular cristae rarely contained dense bodies or lipid globules. SER in tubulovesicular, lamellar, or whorl like complexes were never observed. Testes from tfm/y animals contained elevated levels of several Leydig cell oxidative enzymes. 17 β Hydroxysteroid dehydrogenase activity was normal at birth but significantly reduced in the adult. As a result, testosterone synthesis was reduced 6 to 21 times in testes from tfm/y mice. Collectively these studies suggest that tfm/y Leydig cells are arrested in cytodifferentiation at a stage comparable to the normal animal at birth even though there is adequate gonadotrophin stimulation. Since tissues of the tfm/y mice are insensitive to testosterone it appears that androgen action on the Leydig cell may be necessary for its maturation.