Question

Write an account of the succession of kidney in vertebrates

Answer 1

Although all kidneys are fundamentally nephridial tubes that extract liquid waste from the blood, the kidneys of different animals are by no means homologous structures.

Among vertebrates there are three kinds of nephridial structures serving as kidneys that differ from each other not only in structure and position in relation to the blood system and the excretory tubes, but also in their embryonic history.

The three kinds of kidneys, as named by the English embryologist, Balfour, are the pronephros of a few cyclostomes; the mesonephros of fishes and amphibians; and the metanephros of reptiles, birds, and mammals.

The higher vertebrates, whose kidneys are of the metanephric type, pass through preliminary pronephric and mesonephric stages before the permanent metanephric stage is reached. As is frequently the case, comparative anatomy and embryology have supplementary and confirmatory stories to tell from different angles about the same thing.

Answer 2

Hey Dear,

◆ Development of kidney in vertebrates -

• In vertebrates, kidneys develop from intermediate mesoderm.
• Succession of kidneys in vertebrates takes place in three stages -

1. Pronephros
2. Mesonephros
3. Metanephros

(I) Pronephros -

• nephric tubules arise in the anterior region of kidney.
• it is transitory and completely degenerates in adults

(II) Mesonephros -

• nephric tubules arise in the middle region of kidney.
• functions for the short time during early development

(III) Metanephros -

• nephric tubules arise in the posterior region of kidney.
• it the definitive & permanent working kidney in humans.

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