pharyngeal groove

https://doi.org/10.1351/goldbook.11084

One of several paired grooves in the embryonic endoderm, lateral to the corresponding pharyngeal pouch in the ectoderm.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 791 [Terms] [Paper]