Figure 1. Stages of rodent pituitary development. (a) Oral ectoderm. (b) Rudimentary pouch. (c) Definitive pouch. (d) Adult pituitary gland. I infundibulum; NP neural plate; Nnotochord; PP pituitary placode; OM oral membrane; H heart; F forebrain; MB midbrain; HB hindbrain; RP Rathke’s pouch; AN anterior neural pore; O oral cavity; PL posterior lobe; OC optic chiasm; P pontine flexure; PO pons; IL intermediate lobe; AL anterior lobe; DI diencephalon; SC sphenoid cartilage. Adapted from Sheng and Westphal, Trends in Genetics 1999;15:236-240, with permission (2).