LOCALIZATION AND IDENTIFICATION OF TESTICULAR ESTERASES IN THE RAT

Both the Leydig and Sertoli cells of the rat testis have been shown to be rich in non-specific esterase, but lacking in cholinesterase and "true" lipase. No esterolytic activity has been observed in other elements of testicular tissue. The enzyme activity of the Sertoli cells is mainly localized to the long cytoplasmic processes of these cells, where the sperm heads are embedded. The distribution of esterase activity inside the seminiferous tubules undergoes cyclic variations corresponding to those seen in the morphology of the Sertoli cells. An essentially similar distribution of esterase activity was noticed when α-naphthyl acetate, naphthol-AS acetate, o-indoxyl acetate or Tweens 20 to 60 were used as substrates. Indoxyl acetate was, however, hydrolysed even in an acid medium and this activity was, furthermore, resistant to an organophosphorus inhibitor (E600). It is therefore concluded that the testicular Leydig and Sertoli cells have both A-type and B-type esterase activity, of which the former behaves much like an intracellular peptidase. Demonstration of the activity of electrophoretically separated enzyme proteins have further shown that the histochemically demonstrated non-specific esterase activity in the testis is composed of about eight different enzyme proteins, whose behavior towards inhibitors corresponds to that of tissue sections.