Question

In man, kidney is
(A) Pronephros
(B) Mesonephros
(C) Metanephros
(D) None of the above

Answer 1

The kidney, found in vertebrates, is a bean-shaped organ whose main function is to remove metabolic waste from the body. Humans usually have two kidneys. Nephrons form the basic unit of the kidneys. Glomerulus is a part of the nephron which filters out the toxins from the blood and reabsorbs ions, water, etc. Nephrology is a branch of medical science that involves the study of the kidney and its functions.

Complete answer:
In the fourth week of gestation, the development of kidneys begins in the fetus.
Pronephros marks the appearance of pronephric ducts (predecessor of the mesonephric duct). This is the first stage of kidney development. This is known as a primitive kidney that is functional in the adult form of primitive fishes such as hagfish. In most vertebrates, this type of kidney degenerates at some point in the gestational period, usually the early period.
In the mesonephros stage, mesonephric ducts begin developing. This is the second stage of kidney development. Most aquatic animals have this type of kidney. Between six to ten weeks of a developing fetus, this stage occurs. Despite the resemblance in structure and function to a human kidney, mesonephros is not a part of the human kidney. Structures that resemble and function like nephrons are formed in humans, at this stage.
The last stage of kidney development begins around the fifth week of gestation. At this stage, metanephric blastema and ureteric buds are formed. Throughout the gestational period, fully functional nephrons, urinary bladder and urethra develop. The human kidney is metanephros.

The correct answer is Option (C).

Note:
Sometimes, babies are born without either one or both kidneys. This condition is referred to as renal agenesis. The metanephric mesenchyme and the ureteric bud do not develop properly causing this condition. People can survive and function properly with only one functioning kidney. Chronic renal failure is observed when both the kidneys are damaged severely.