part of located in develops from has potential to develop into ectoderm proctodeum amnioproctodeal invagination proctodaeum anus porus Wikipedia:Proctodeum Inward fold on the surface of the embryonic ectoderm that develops into an ectodermal terminal part of the digestive tract. TAO:0000066 NCIT:C34278 anal pit AAO:0011087 ZFA:0000066 XAO:0001019 embryonic proctodaeum EMAPA:25038 EHDAA2:0000121 VHOG:0000139 anal region presumptive gut external anal region pit