Development of the Kidney

The correct answer is D.


Explanation:

The metanephric duct (also known as the ureteric bud) is a diverticulum of the mesonephric duct. It grows to the metanephric mass of the urogenital ridge. It induces the development of the metanephros, which will give rise to the excretory units of the definitive kidney. The metanephros, in turn, induces the metanephric duct to divide into the calyces and the collecting tubules.

The allantois (choice A) is an endodermal diverticulum of the yolk sac. It becomes incorporated into the urogenital sinus and contributes to the formation of the urinary bladder. It is not involved with the formation of the kidney.

The mesonephric duct (choice B) is a mesodermal duct into which the mesonephric tubules drain. The mesonephric duct is the same as the pronephric duct, but at a later stage of development. The mesonephric duct develops into the ductus deferens in the male. The metanephric duct is a diverticulum of the mesonephric duct.

The mesonephros (choice C) is the embryonic kidney, which functions in the embryo before the metanephros (or definitive kidney) develops. The mesonephros develops from the urogenital ridge.

The urogenital ridge (choice E) is a longitudinal elevation of the intermediate mesoderm. The embryonic and adult kidneys, as well as the gonads, develop from this mesoderm.

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