CELLS OF THE PHOTORECEPTOR LINE IN THE PINEAL ORGAN OF AN ADULT MARSUPIAL, DIDELPHIS-ALBIVENTRIS

We report the presence of atypical pinealocytes as components of epiph yseal follicles in the adult South American opossum Didelphis albivent ris. Their main characteristic is a bulbous-shaped apical cytoplasmic extension which protrudes towards the follicular lumen among the micro villi and cilia of neighbouring ependymal cells. They resemble the pho toreceptor-like pinealocytes of sauropsids and developing photorecepto rs in the retina of newborn mammals. Morphological characteristics ena ble us to classify them as cells of the receptor line.