Affe und Orang Utan licht-und elektronenmikroskopisch vergleichend untersucht. Die Lamina propria des Tubulus seminiferus besteht a w Basallamina, Grundsubstanz, Kollagenfasern, Fibroblasten und Myofibroblasten. Myofibroblasten sind durch Myofilamente, Dense patches sowie eine Basallamina auf ihrem Plasmalemm gekennzeichnet. Die Myofibroblastenschichten liegen stets in der Nahe des Keimepithels, peripher liegen zirkulare Fibroblastenschichten.Summary: The lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates : Mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan.The lamina propria consists of basal lamina, ground substance, collagen fibers,fibroblasts and myofibroblasts. Myofibroblasts are characterized by myofilaments, dense patches and a basal lamina covering their plasmalemma. The layers of myofibroblasts always lie adjacent to the germinal epithelium, while the surrounding fibroblast layers are located peripherally.