Some functional aspects of the ultrastructure of rat pinealocytes

An analysis of more than 75000 electron micrographs from 84 intact control and 167 experimental male rats divided into 11 groups subjected to various treatments, was performed in the present study, a special attention being paid to the relation of cytoplasmic organelles to the processes of synthesis and secretion of pinealocytes. From these observations the following conclusions have been drawn: 1. specific pineal cells - the pinealocytes - show several attributes of metabolically active endocrine cells; 2. at least two probably intimately related secretory processes are present in the rat pinealocytes; 3. several cytoplasmic structures may be involved in the secretory mechanism of the rat pinealocytes.