Health Sciences 4320A/B Chapter Notes - Chapter 11: Lateral Plate Mesoderm, Bile Duct, Cloacal Membrane

• School: Western University
• Department: Health Sciences
• Course: Health Sciences 4320A/B
• Professor: Christine Bell

Document Summary

Primordial gut (pg) develops during week 4 as the head, caudal eminence, and lateral fold incorporate the dorsal part of the umbilical vesicle. Pg is initially closed at the cranial end by the oropharyngeal membrane and at its caudal end by the cloacal membrane. Endoderm of the pg forms most the gut, epithelium and glands. Epithelium of the cranial and caudal ends of the digestive tract is derived from ectoderm of the stomodeum and anal pit (proctodeum) Endoderm specifies temporal and positional information which is essential for the development of the gut. Muscular, connective tissue and other layers of the wall of the digestive tract are derived from the splanchnic mesenchyme surrounding the pg. The pg is divided into the foregut, midgut and hindgut. Derivatives of the foregut are: primordial pharynx and its derivatives, lower respiratory system, esophagus and stomach, duodenum, distal to the opening of the bile duct, liver, biliary apparatus (hepatic ducts, gallbladder and bile duct) and pancreas.