[Development and differentiation of the rat epididymis. II: histochemical aspects of the peritubular zone]

Development of the contractile peritubular structures of rat testis, from birth to full maturation, was investigated by histochemical evaluation of alkaline phosphatase activity (A.P.A.) at 0, 16, 22 e 35 days of age. A.P.A. appeared at 6 days, age of appearance also of the cytoplasmic microfilaments of peritubular cells. The correlation between cytoplasmic microfilaments and A.P.A. was confirmed by the pattern of A.P.A. positivity at 6 degree day, when the inner peritubular cells layer, in which the microfilaments are present, are more positive than the outer layer in which the microfilaments are not yet present. These findings give further support to the belief that the cytoplasmic microfilaments of peritubular cells are contractile structures.