Snout formation. Descriptions of the three stages of the snout-formation period, along with examples for each stage. (A) S. abaster embryo (dechorionated) with ventrally developing jaws. (B) H. abdominalis larva with jaws rising frontally. (C) S. abaster larva with an elongated snout. Scale bars are 1 mm.
Sommer et al. BMC Developmental Biology 2012 12:39 doi:10.1186/1471-213X-12-39