proctodaeum

enUK

proc·to·de·um

also proc·to·dae·um P0578850 (prŏk′tə-dē′əm)n. pl. proc·to·de·a (-dē′ə) or proc·to·de·ums also proc·to·dae·a (-dē′ə) or proc·to·dae·ums An inward fold on the surface of the embryonic ectoderm that develops into part of the anal passage.
[New Latin prōctodeum : Greek prōktos, anus + New Latin -odeum (probably from Greek hodaion, neuter of hodaios, on the way, from hodos, way).]