At approximately day 1

Normal fetal weight: 630 gm

Reference

Moore KL, Persaud TVN. 1998. The Developing Human: Clinically Oriented Embryology. 6th ed. Philadelphia: WB Saunders Co.

At approximately day 1

The absorptive epithelial cells resemble those of the adult intestine.

Reference [PubMed Link]

Montgomery RK, Mulberg AE, Grand RJ. 1999. Development of the human gastrointestinal tract: twenty years of progress. Gastroenterology 116(3):702-731.