PHOTORECEPTORAL AND SECRETORY STRUCTURES IN AVIAN PINEAL ORGAN

Electron microscopic studies on the pineal organ of the adult Japanese quail and the White Leghorn chicken showed three cell types present within the cell cluster: ependymal, secretory, and photoreceptor cells. Ependymal cells had apical cilia with the 9 + 2 arrangement of the microtubules; secretory cells had numerous membrane-limited secretory granules throughout the cytoplasm; and the photoreceptor cells had synaptic contacts along their basal border and modified cilia connecting the apical portion of the cells to a membranous lamellar complex located in the lumen of the follicle. © 1969 Academic Press, Inc.