Questions & Answers

The ureters of opisthonephric kidneys represent
A. Wolffian ducts in the male
B. Mullerian duct in female
C. Wolffian duct in both sexes
D. Both A and B

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Hint: Opisthonephric kidney is the adult kidney of amniotes - such as the shark and mudpuppy and develops from all or most of the nephric ridge posterior to the pronephros. It is formed from the extended mesonephros along with tubules from the posterior nephric ridge. The functional embryonic kidney in amniotes is the pronephros.

Complete answer: The pronephros undergo apoptosis to form mesonephros. In fishes, the nephron degenerates but the organ remains and becomes a component of the immune system. In mammals, a functional pronephros, in the context of an organ performing waste excretion or osmoregulation, does not develop. However, a kidney primordium that runs along the intermediate mesoderm does form and links up to the cloaca. This duct is known as the pronephric duct, mesonephric duct, or wolffian duct. Wolffian ducts (WDs) are the embryonic structures that form the male internal genitalia. These ducts develop in both the male and female embryos. However, in the female, they subsequently regress, whereas in the male they are stabilized by testosterone. The wolffian duct (also known as the mesonephric duct) is one of the paired embryogenic tubules that drain the primitive kidney (mesonephros) to the cloaca. It also gives off a lateral branch forming the ureteric bud. While this transient primordium never forms functional nephrons, the duct derived from it is essential to the development of the more complex later kidneys.
So, the correct answer is option-A, i.e., Wolffian ducts in male

Note: Pronephros is the most basic of the three excretory organs that develop in vertebrates, corresponding to the first stage of kidney development. It is succeeded by the mesonephros, which in fish and amphibians remains as the adult kidney. In amniotes, the mesonephros is the embryonic kidney and a more complex metanephros acts as the adult kidney. Once more advanced kidney forms, the previous version typically degenerates by apoptosis or becomes part of the male reproductive system.