Which of the following structure develops from the proctodeum?
Proctodeum or ectoderm lined anal pit is formed by the accumulation of mesodermal cells around the periphery of the anal membrane. This gives rise to lower 1/3rd of the anal canal. Cloaca is the terminal expanded poion of the primitive hindgut. The cloacal chamber is divided into dorsal and ventral cavities. The dorsal division gives rise to rectum and upper half of anal canal. The lower half of anal canal develops from proctodeum. Ref: Essentials Of Human Embryology (Rev. Edn) By Bhatnagar, S.M page 122
Rectum
Sigmoid colon
Upper 2/3rd of anal canal
Lower 1/3rd of anal canal