You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Anal opening is formed in which week of embryonic development: and explain in detail?
The hindgut terminates temporarily at an ectodermal-endodermal membrane, the cloacal membrane. This membrane separates the upper pa of the anal canal, derived from endoderm, from the lower pa, called the proctoderm that is formed by an invagination pit lined by ectoderm. The membrane breaks down in the seventh week to create the opening for the anus. Ref: Langman's embryology 11th edition Chapter 7.