Fig. 7
The floor plate is abnormally broad and cell-rich in ntl mutants. Comparisons of expression of col2a1 in wild types (upper panels) and ntl mutants (lower) at rostral (left) and caudal (right) axial levels. Left side views of whole-mounted 24-hr embryos, with anterior to the left and dorsal to the top. RNA in situ hybridization with a col2a1 probe (Yan et al., 1995). Within the spinal cord the wild-type floor plate is a 1-cell-wide row (A, B, white arrowhead). Notochord (dark arrowhead) and hypochord (hy) also express the marker. Often the floor plate in the ntl mutant trunk appears irregular (C, D), in a row several cells wide. In addition, ventral projections of cells with the col2a1 expression characteristic of hypochord (arrow) are often seen in the ntl mutant caudal trunk (D). However, expression of radar, a marker characteristic of the hypochord in wild-type embryos, was not detected in ntl mutants by Rissi et al. (1995). Scale bar, 25 um. |
Reprinted from Developmental Biology, 187(2), Halpern, M.E., Hatta, K., Amacher, S.L., Talbot, W.S., Yan, Y.-L., Thisse, B., Thisse, C., Postlethwait, J.H., and Kimmel, C.B., Genetic interactions in zebrafish midline development, 154-170, Copyright (1997) with permission from Elsevier. Full text @ Dev. Biol.