BIO380H5 Lecture Notes - Lecture 27: Mesonephric Duct, Mesonephros, Ureteric Bud
Document Summary
Urogenital system arises from the intermediate mesoderm of the early embryo. Early forms of the kidney (three successive phases) Pronephros- this type found in the lowest vertebrates. Human embryos- urinary system consists of a few segnentally arranged sets of epithelial cords that differentiate from the anterior intermediate mesoderms at 22 days of gestation- structure called nephrotome. Nephrotome connected laterally with a pair of primary nephric/ pronephric ducts that grow towards the cloaca. Early stages of urinary system development depend on the action of the retinoic acid which sets the expression limits for hox 4-11 which determine the craniocaudal limits of the early urinary system. Mesonephric unit- vascular glomerulus, glomerular capsule wirh mesonephric tubule which empties into the primary nephric duct known as the mesonephric duct. Mesonephric tubules arise as outgrowths from the primary nephric ducts. Ureteric bud developement is an epithelial outgrowth by the mesonephric duct near its attachment site to the cloaca.
