XB-IMG-81094
Xenbase Image ID: 81094
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FIG. 1. (a) Schematic of the GZ in larval Xenopus eye. The GZ
is a bilayered ring, whose outer pigmented germinal cells (circles)
form a smooth continuous layer with the PRE (squares) proximally
and the iris (IR) distally, and whose inner neuroepithelial layer is
continuous with neural retina. Animals sacrificed immediately following
an injection of 3H-labeled thymidine at any larval stage from
late-30 through metamorphosis show labeled cells only in the GZ
proper. Animals sacrificed many weeks after a pulse of 3H-labeled
thymidine show a "birthdate ring" (BR) of labeled cells displaced
from the GZ by new growth, formed after the pulse, in which the label
has been diluted to background. (b) Three-dimensional pattern of
growth is annular with the GZ sitting on the rim of the retinal
epithelia. Immediately surrounding the optic nerve are the oldest
cells-the "back" of the eye that differentiated in the 2.5- to 4-day
embryo. The rest of the eye can be viewed as the cumulative set of
BRs; the earlier ones are at the back; and the more recent BRs are
ever closer to the front-here visualized as PRE contours in a
chimeric eye reconstructed from serial sections cut approximately
perpendicular to the optic axis. (c) Operative schematics for the
orthotopic transplantation of dorsal (12 or 1 o'clock) or anterior (3
o'clock) germinal cells between right eyes of embryos. Image published in: Hunt RK et al. (1987) Copyright © 1987. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View |