Fig. 5. A collection of neural plate markers. At the top of the panels is a schematic drawing of the neural plate when it consists of six rows of cells, with each square representing a neural plate cell. Names of each cell are indicated, and should be prefixed with an `a9.' for a-line cells, `A9.' for A-line cells and `b9.' for b-line cells. I-VI indicate the row number, with Row I the closest to the blastopore, which is at the most caudal position of the neural plate. Colour scheme used is as in Fig. 1. (A-F) For each marker, two stages are shown; when the neural plate has six rows of cells (left) and when the neural plate has seven rows of cells (right). Nuclei are labelled to allow easy identification of individual cells. A schematic drawing of the neural plate with the blastomeres expressing each marker coloured in blue is presented below each embryo.