Figure 16.

Stages 33 and 34: Anterior–posterior axis reads left to right in both images. Scale bar = 1 mm. Stage 33 (7 days). Stage 34 (7 ¼ days). Abbreviations: al, alula; cf, choroid fissure; el, eyelid; et, egg tooth; fg, feather germ; fl, forelimb; hal, hallux; hl, hindlimb; ica, internal carotid artery; le, lens vesicle; md, mandibular process; ms, mesencephalon; mt, metencephalon; mx, maxillary process; my, myelencephalon; nar, nares; ot, otic vesicle; pr, pigmented retina of eye; tb, tailbud; te, telencephalon; tmt, tarsometatarsus; v1, lateral ventricle of telencephalon; v4, fourth vesicle of myelencephalon. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]