part of preceded by NF stage 28 NF stage 29 and 30 Nieuwkoop and Faber stage 29/30, corresponding to an embryo of age 1 day, 11 hr at 22-24 Celsius and having the following external morphological criteria: Gray eye cup showing through for the first time. Fin transparent up to the base over its whole length. Tail bud distinct. Length: 4.0 - 4.5 mm. XAO:1000045 xenopus_developmental_stage late tailbud stage NF stage