A Peculiar Lamellated Body Observed in the Cells of the Pigment Epithelium of the Retina of the Bat, Pipistrellus abramus

During the course of a study of the fine structure of the retinal pigmented epithelium of the bat (1), a peculiar body showing a quite regular texture-like pattern was observed within the constituent pigment cells. The fine structure of this body seems to be noteworthy in several respects and is described here. The eye of the bat was fixed with a modified buffered osmium tetroxide solution (Caulfield (2)). Prior to dissection, the bats were anesthetized with ether under conditions of dark adaption. The tissue was imbedded in n-butyl-methacrylate, and sections were cut with a Porter-Blum or JUM microtome. A JEM-3C microscope was used for the observations. The pigment epithelial cell of the bat retina is flattened and cuboidal in shape. I t shows many cell processes on the free surface. The basal cell border presents complicated plications and rests on the connective tissue layer of the choroid. The cell body is recognized as being filled with a dense network of tubular structures, the greater part of which is free from the particles of Palade. Hence, the structure may correspond to the so called "smooth surfaced endoplasmic reticulum." The rough surfaced endoplasmic reticulum and free particles of Palade are also recognizable in small amounts scattered about in the cytoplasm. In Fig. 1, one can recognize a characteristic body somewhere near the center of the pigment cell. I t presents a quadrangular profile 1 x 3 #. The long axis is almost parallel to that of the outer segment of the adjacent rod. At first glance, its peculiar structural pattern reminds us of a striped cloth or of a Japanese bamboo blind (sudare). Upon closer observation (Figs. 2 to 4), the structures corresponding to the woof appear to be composed of regularly and closely piled flattened membranous sacs. The over-all thickness of each