Publisher Summary This chapter describes the anatomy of the development of the foetal small intestine. It explores whether biology or not the foetus is a precursor to the adult, or an adaptive stage of development in its own right. Small intestinal development passes through many phases of growth. During foetal life, the small intestine is very responsive to the presence of growth factors, hormones. Growth and function can be altered by these agents. The capacity for tissues and cells to adapt or change structure and function is also subject to regulatory mechanisms. There are developmental outcomes for/from the developing small intestine that are crucial for neonatal survival. The functional and structural correlates of this biological role are highly conserved across species, irrespective of the later life (adult) digestive specificities. Consistency of the pattern in the embryonic period of development of tissues and cells is also conserved. Future studies in selective breeding/conception, including current and future developments in genetics, are critical in understanding of how the gut has adapted during evolution.