R- and B-cadherin expression defines subpopulations of glial cells involved in axonal guidance in the optic nerve head of the chicken.
Glial cells play a crucial role in the organization and function of the nervous system. Cell-cell adhesion receptors of the cadherin family have been shown to participate in distinct morphogenetic processes throughout the development of the CNS, but little is known about glial expression of cadherins. Applying immunofluorescence and confocal laser scanning microscopy, we investigated R- and B-cadherin expression in relation to the glial cell differentiation in the optic nerve head and pecten oculi of developing chicken. Throughout embryonic development, R- and B-cadherin were expressed in distinct cell populations, which differentiated into distinct subtypes of glial cells. R-cadherin was located in the glia limitans perivascularis et superficialis of the optic nerve and in cells bordering the optic nerve head, where it comes in contact with the retina. B-cadherin was located in the glia limitans perivascularis et superficialis of the pecten oculi and in a subset of cells at the retinal border. R-cadherin-expressing cells differentiated unequivocally into a glial fibrillary acidic protein (GFAP)-positive but glutamine synthetase (GS)-negative phenotype, whereas B-cadherin-expressing glia developed into a GS-positive but GFAP-negative phenotype. In addition, the B-cadherin-positive population developed into a highly pigmented cell type, which was consistently associated with pecten-type capillaries. By contrast, the R-cadherin-positive glia remained unpigmented and surrounded normal brain-phenotype capillaries. These data suggest that glial cells, like neurons, may use the expression of different cadherins to segregate and differentiate into distinct subtypes, which goes hand in hand with their involvement in special functions and morphogenetic processes. To address this issue, we selectively lysed both glial subtypes in developing embryos by microinjection of R- and B-cadherin antibodies with complement. First evidence is presented for R-cadherin-positive glial cells as crucial to the organization of the optic nerve and axonal guidance at its lateral margin. B-cadherin-positive cells are involved in the axonal guidance at the pecteneal margin, avoiding the ingrowth of axons into the pecten.
Gerhardt
H
H
Institute of Pathology, University of Tübingen, Tübingen, Germany.
Rascher
G
G
Schuck
J
J
Weigold
U
U
Redies
C
C
Wolburg
H
H
D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D002642:Chick Embryo; D002645:Chickens; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D020439:Growth Cones / Q000378:metabolism* / Q000648:ultrastructure; D009457:Neuroglia / Q000145:classification / Q000378:metabolism* / Q000648:ultrastructure; D009900:Optic Nerve / Q000196:embryology* / Q000254:growth & development* / Q000648:ultrastructure
D015820:Cadherins