Question

In Fishes, the kidney is
A. Pronephros
B. Mesonephros
C. Metanephros
D. Holonephros

Answer 1

Hint: Kidneys play an important role called excretion, which is necessary to excrete out unnecessary metabolite or toxic products from the blood through filtration process. The product which is excreted out is known as urine, Urine is composed of different kind of compound which is depend on different kind of animal species in animal kingdom, such compound name as uric acid (uricotelism), ammonia (ammonotelic), urea (ureotelism) and guanine (arachnida).

Complete answer:
Different kinds of animals possess different kinds of kidneys in the animal kingdom, which perform excretion processes. In fishes the mesonephric type kidney found it also present in amphibians. Mesonephros forms the anterior portion of permanent kidney. Mesonephric nephrons do not form any mature kidney.

Hence, the correct answer is option (B).

Additional information:
> Option A: Pronephros is the first stage of development of the kidney in invertebrates which act as the most basic of the excretory organs. It is developed from intermediate mesoderm, lying between the paraxial mesoderm and lateral plate. Glomerulus is projected into the coelom, in the proneuron case.

> Option C: Metanephros is a permanent kidney in reptiles, birds and mammals that is developing by the 10th week in human embryos of the lower part of the wolffian duct and replaces the embryonic structure known as mesonephros.

> Option D: Holonephros is a type of kidney found in the larvae of cyclostomes and the gymnophiona. This kidney arises for the whole mass of nephrogenic tissue and forms a simple single tubule in each segment.

Note: The development process of kidney is known as nephrogenesis, which describes the embryologic origin of kidney. The development process kidney marked by four phases and moving from simple to more advanced kidney:- archinephros, pronephros, mesonephros and metanephros.