NF stage 15

^ http://purl.obolibrary.org/obo/XAO_1000025

Nieuwkoop and Faber stage 15, corresponding to an embryo of age 17 hr 30 min at 22-24 Celsius and having the following external morphological criteria: Early neural fold stage. Presumptive cement gland faintly circumscribed. Anterior part of neural plate roundish. Neural folds distinct, except medio-rostrally; initial formation of sharp inner ridges on neural folds in rhombencephalic region. Length: 1.5 - 1.6 mm. [ https://www.worldcat.org/search?q=bn%3A0815318960 ]