part_of part of part of overlaps develops from embryonic structure pharyngeal arch endoderm of foregut pharyngeal pouch EHDAA:1669 The pouches are polarized structures. For example, whereas the rostral half of each pouch expresses Bmp-7, the caudal half expresses FGF-8 and the dorsal aspect of each pouch is marked via its expression of Pax-1. each pouch has an individual sense of identity. Shh expression is a prominent early feature of the caudal endoderm of the second arch, and individual pouches mark the anterior limits of expression of Hox genes within the pharyngeal endoderm; Hox-a2 has a rostral boundary at the second pouch, Hox-a3 at the third pouch and Hox-a4 at the most caudal pouch[PMID:16313389] XAO:0000282 UBERON:0004117 EFO:0003627 ZFA:0001106 EMAPA:32752 visceral pouches pharyngeal pouches EHDAA:1086 NCIT:C34252 Wikipedia:Pharyngeal_pouch_(embryology) EHDAA:579 branchial pouch TAO:0001106 EHDAA:617 SCTID:34674002 An internal pocketing of pharyngeal endoderm that contacts a region of ectoderm (a pharyngeal cleft) and interdigitates in the anterior and posterior directions with the pharyngeal arches. VHOG:0001203 FMA:293063 AAO:0011113 embryonic tissue early pharyngeal endoderm pharyngeal arch system