On the presence of conspicuous electron dense bodies in the pinealocytes of the pig.

The pinealocytes of the pig contain a large number of aldehydefuchsin positive granules. In order to determine their nature an ultrastructural study was carried out. Numerous bodies having a maximal diameter of about 1,600 nm were found. These elements showed a great variety of internal structure, ranging from a "homogeneous" content and amorphous dense aggregates to lamellate bodies. Although only a few of them displayed a positive reaction for acid phosphatase, their morphological appearance strongly suggests that they belong to the lysosomal system.