CD44 EXPRESSION IN THE DEVELOPING HUMAN RETINA

Background: CD44, the transmembrane adhesion molecule, is expressed in the fetal brain and supposed to mediate neuroglial interactions. We e valuated the expression and distribution of CD44 in the developing hum an retina. Methods: Four developing human eyes were evaluated at 6, 10 , 16, and 21 weeks of gestation, as well as the eyes of one infant and four adults. Frozen sections were immunohistochemically stained with monoclonal antibodies to three human CD44 clones (BU52, F10-44-2, and DF1485) and to vimentin, and antiserum to glial fibrillary acidic prot ein (GFAP). Specimens were evaluated by light and electron microscopy. Results: Positive immunostaining for CD44 was first detected at 21 we eks of gestation in the longitudinal fibers that extended from the inn er to the outer limiting membrane and around capillary vessels with th e simultaneous expression of vimentin and GFAP. Immunoelectron microsc opy demonstrated the presence of CD44 on the surface of Muller cells a nd astrocytes. CD44 was faintly seen in the Muller cells in the periph ery and definitely present in the astrocytes in the infant and adult r etinas Conclusion: CD44 was expressed in Muller cells at a late stage of fetal development and in the fetal, infant, and adult astrocytes, w hich suggests that it is important in the morphogenesis and homeostasi s of the neural retina.