Changes

The small intestine develops from the digestive tube, which exists ventrally in the developing embryo. The digestive tube is endoderm, and therefore the small intestine and it's associated glands develop primarily from endoderm. Splanchnic mesoderm surrounds the digestive tube and gives rise to muscles of the tunica muscularis (for peristalsis), blood vessels in the submucosa and connective tissue of the serosa.  

The small intestine develops from the digestive tube, which exists ventrally in the developing embryo. The digestive tube is endoderm, and therefore the small intestine and it's associated glands develop primarily from endoderm. Splanchnic mesoderm surrounds the digestive tube and gives rise to muscles of the tunica muscularis (for peristalsis), blood vessels in the submucosa and connective tissue of the serosa.  

The intestines begin as a straight tube, suspended by the dorsal mesentry. They then loop ventrally. This slips out of the abdomen into the umbilical cord where growth continues. The cranial loop becomes the small intestine. It elongates and becomes extensively coiled. It then undergoes a 270° rotation about the cranial mesenteric artery so that the caecum ends up on the right.

The intestines begin as a straight tube, suspended by the dorsal mesentry. The midgut and mesentry elongate to form a loop. The descending limb of the loop will form the duodenum, jejunum and ileum. The ascending limb will form the terminal portion of the ileum, caecum and first half of the colon. The midgut loop rotates about the cranial mesenteric artery in a clockwise direction (when viewed dorsoventrally).It undergoes a 270° rotation so that the caecum and ascending colon ends up on the right, and the small intestine ends up on the left.

PICTURE

PICTURE