W. Knabe et Hj. Kuhn, PATTERN OF CELL-DEATH DURING OPTIC CUP FORMATION IN THE TREE SHREW TUPAIA-BELANGERI, Journal of comparative neurology, 401(3), 1998, pp. 352-366
Developmental cell death during optic cup formation was investigated i
n the tree shrew Tupaia belangeri. Twenty-six embryos from days 12 to
16 of prenatal ontogenesis were studied by light microscopy. Prior to
the optic vesicle stage, a dorsal area of cell death surrounded the lu
men of the V-shaped optic evagination (phase 1). A ventral band of dea
d cells, found in the optic vesicle (phase 2), preceded a dorsal focus
of cell death (phase 3) previously described as a characteristic avia
n feature. During further invagination (phase 4), a peak of cell death
was represented by a ventrodorsal band extending from the diencephalo
n over the complete optic anlage. The main areas of cell death found i
n phases 2 to 4 were, topographically, segments of this band. Also, th
e distinct areas of cell death reported in the literature for the vert
ebrate species studied so far fit well into this ventrodorsal band fou
nd in Tupaia. Thus, most probably, a common spatio-temporal sequence o
f cell death exists in all of them. In Tupaia, dead cells concentrated
at the diencephalic insertion of the optic stalk, the suboptic necrot
ic center (SONC) reported by several authors, were part of the early v
entral band of cell death originating from the median floor of the pro
sencephalon (phase 2). During optic cup formation, the SONC was part o
f the ventrodorsal band and, thus, was not secondarily formed by the s
ubdivision of a pre-existing distal ventral area of cell death as repo
rted for several other vertebrates. J. Comp. Neurol. 401:352-366, 1998
. (C) 1998 Wiley-Liss, Inc.