Embryonic Development of Vertebrates and Formation of Tubules

During the embryonic development of vertebrates, the urinary system undergoes a series of transformations that lead to the formation of a functional kidney. The development of the kidney is divided into three stages, each of which involves the formation of a different type of tubule.

1. Pronephric Tubules:

The first tubules to form during embryonic development are the pronephric tubules. These tubules are formed from the intermediate mesoderm and are responsible for the excretion of waste products during the early stages of embryonic development. However, these tubules are non-functional and are replaced by the mesonephric tubules later on.

2. Mesonephric Tubules:

The mesonephric tubules are the second type of tubules to form during embryonic development. These tubules are formed from the intermediate mesoderm and are responsible for the excretion of waste products during mid-embryonic development. These tubules are also involved in the formation of the male reproductive system.

3. Metanephric Tubules:

The final and most important type of tubules to form during embryonic development are the metanephric tubules. These tubules are formed from the ureteric bud and the metanephric mesoderm and are responsible for the formation of the adult human kidney. The metanephric tubules are the functional units of the kidney and are responsible for the filtration of blood and the excretion of waste products.

Conclusion:

Therefore, the correct answer to the question is option 'D' (Pronephric), as the pronephric tubules are the first tubules to form during embryonic development in vertebrates.

Pronephridic.1 st sequence of kidney formed in verterbral embryo.pronephridic primordium develop from ibtermediate mesoderm.lying btw paraxial mesoderm and lateral plate..i think it might be correct...