Primary cilia in vertebrate corneal endothelial cells.
The presence of primary cilia in corneal endothelial cells of a range of species from six non-mammalian vertebrate classes (Agnatha, Elasmobranchii, Amphibia, Teleostei, Reptilia and Aves) is examined by scanning and transmission electron microscopy. Our aim is to assess whether these non-motile cilia protruding into the anterior chamber of the eye are a consistent phylogenetic feature of the corneal endothelium and if a quantitative comparison of their morphology is able to shed any new light on their function. The length (0.42-3.80 microm) and width (0.12-0.44 microm) of the primary cilia varied but were closely allied with previous studies in mammals. However, interspecific differences such as the presence of a terminal swelling in the Teleostei and Amphibia suggest there are functional differences. Approximately one-third of the endothelial cells possess cilia but the extent of protrusion above the cell surface varies greatly, supporting a dynamic process of retraction and elongation. The absence of primary cilia in primitive vertebrates (Agnatha and Elasmobranchii) that possess other mechanisms to control corneal hydration suggests an osmoregulatory and/or chemosensory function.
Department of Anatomy and Developmental Biology, School of Biomedical Sciences, The University of Queensland, Brisbane 4072, Queensland, Australia. s.collin@uq.edu.au
Shaun P
SP
Collin
H
H
Barry Collin
D000663:Amphibians / Q000033:anatomy & histology; D000818:Animals; D001717:Birds / Q000033:anatomy & histology; D002923:Cilia / Q000648:ultrastructure*; D003315:Cornea / Q000166:cytology*; D004728:Endothelium, Corneal / Q000648:ultrastructure*; D005399:Fishes / Q000033:anatomy & histology; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D012104:Reptiles / Q000033:anatomy & histology; D014714:Vertebrates / Q000033:anatomy & histology*