Shh signalling restricts the expression of Gcm2 and controls the position of the developing parathyroids

► The parathyroid glands originate from the Gcm2-expressing caudal pharyngeal pouches. ► Fish, chick and mouse show highly reduced Shh signalling where Gcm2 is expressed. ► During early development, HH signalling reduction results in the loss of chick Gcm2. ► Later on, it induces ectopic Gcm2 in the second and first pharyngeal epithelium. ► A conserved regulatory mechanism of Gcm2 by HH signalling defines pouch derivatives.