Pericentriolar processes of photoreceptor cell basal bodies in the mammalian retina.
Pericentriolar processes (arm-like fibers) of the migrating centrioles (diplosome) in differentiating retinal photoreceptor cells were examined in six mammalian species (hamster, vole, rat, rabbit, ferret, cat). These processes emanate in a radial fashion from one end of the centrioles comprising the photoreceptor diplosome. The pericentriolar processes of the basal body are first observed as the diplosome migrates toward the apical plasmalemma, suggesting that centrioles are committed early-on to developing such processes. One pericentriolar process arises from each set of microtubular triplets comprising the centriole and are apicoexternally oriented at an angle of between 30 and 60 degrees with the centriolar axis. Prior to the arrival of one of the centrioles at the apical plasmalemma these processes connect with an electron-dense portion of a centriole-associated vacuole. The diplosome migrates to the apical plasmalemma where one centriole (the presumptive basal body) orients perpendicularly to the apical plasmalemma. The centriole-associated vacuole appears to fuse with the plasmalemma. The pericentriolar processes appear to attach to this fusion site on the plasmalemma which is a region of the membrane characterized by increased electron density (the basilar plate). Invagination of the apical membrane, which occurs at this same site, is accompanied by a lengthening of the microtubules forming a cilium and is observed as an outpouching of the plasmalemma within the aforementioned invagination. The associated vacuole apparently becomes continuous with the apical plasmalemma. These pericentriolar processes appear to be functionally involved in ciliogenesis and offer structural stability between the basal body, the plasmalemma and indirectly the cilium.
D000818:Animals; D003411:Arvicolinae; D002415:Cats; D002462:Cell Membrane / Q000648:ultrastructure; D002502:Centrioles / Q000648:ultrastructure*; D006224:Cricetinae; D005289:Ferrets; D008322:Mammals / Q000033:anatomy & histology*; D008647:Mesocricetus; D009115:Muridae; D009940:Organoids / Q000648:ultrastructure*; D010786:Photoreceptor Cells / Q000648:ultrastructure*; D011817:Rabbits; D012160:Retina / Q000648:ultrastructure*; D013045:Species Specificity