Cadherins are homophilic cell adhesion molecules that control
development of a variety of tissues and maintenance of adult
structures. Although cadherins have been implicated in the
development of the brain, including the visual system, in several
vertebrate species, little is known of their role in zebrafish.
In this study, we examined distribution of cadherin-2 (Cdh2,
N-cadherin) in the visual system of developing and adult zebrafish
using both immunocytochemical and in situ hybridization
methods, and we compared Cdh2 distribution to that of the
previously reported and closely related cadherin-4 (Cdh4,
R-cadherin). As in other vertebrates, in zebrafish embryos Cdh2
was widely expressed in the early nervous system, but its
expression became more restricted as development proceeded.
Cdh4 was not detectable until later in development, at about
the time when the first ganglion cells are generated. Cdh2 and
Cdh4 were expressed in distinct regions of developing visual
structures, including the lens. We hypothesize that the
differential expression of these two cadherins in developing
zebrafish visual structures reflects functionally different
roles in the development of the vertebrate visual system.