Enzyme histochemical studies on acid phosphatase in the cerebellum of young Gunn rats.

Cerebella from 20-day-old homozygous (jj) and heterozygous (j+) Gunn rats were tested histochemically for the presence of acid phosphatase. The j+ rat cerebellum as well as the jj rat cerebellum with wet weights over 120 mg showed a strong acid phosphatase activity in the pia mater and in endothelial cells. A strong acid phosphatase activity was also recognized in small cells with a diameter of about 8 micrometers and large cells with a diameter of about 25 micrometers in the hypoplastic cerebellum of jj rats. The small cells were present in the lingula, centralis, culmen, declive, tuber, pyramis, and dorsal part of the uvula of the jj rat cerebellum with wet weight below 120 mg. The large cells were observed only in severely damaged lobes. Neither small cells nor large cells were found in the nodulus even in a cerebellum with a high degree of hypoplasia. Slightly damaged cerebella with wet weight of 100 to 150 mg showed hypoplasia mainly in the anterior lobe including the lingula, centralis, and culmen as well as in the declive and tuber, where no small cells were detected.