Chapter 27, Problem 1TYR

The ductus deferens develops from the _______.of the embryo

a. mesonephric duct

b. paramesonephric duct

c. phallus

d. labioscrotal folds

e. urogenital folds

Summary Introduction

Introduction:

Ductus deferens also called as the vas deferens is a male reproductive unit in humans that helps in transporting the sperm from the epididymis to the ejaculatory duct in the penis. In humans, it is a coiled structure of about 30 cm. The sperm ejaculation is effected through the vas deferens and ejected out by the urethra.

Answer to Problem 1TYR

Correct answer:

The ductus deferens arises from the mesonephric duct of the embryo. Therefore, option (a) is correct.

Explanation of Solution

Justify reasons for the correct statement:

A mesonephric duct or Wolffian structure is a primitive development of the urogenital system in humans. In males, it connects the excretory system to the reproductive system that includes epididymis, vas deferens, and seminal vesicle.  In embryogenesis, these mesonephric ducts bind to the testosterone hormone and activate the androgen receptor, which induces the male sex determinant factor in the developing fetus. In adult males, it functions to store and transport the sperm to the ejaculatory duct.

Option (a) is given as “mesonephric duct”

Mesonephric ducts in the embryonic stage gives rise to the ductus deferens (vas deferens) in the male adult.

Hence, option (a) is correct.

Justify reasons for the incorrect statements:

Option (b) is given as “paramesonephric duct”

Paramesonephric duct is found in both the sexes during the embryonic development. But it develops into the female urogenital sinus of sinus tubercle, whereas in males it is completely lost during later stages of embryonic development. Hence, it is wrong answer.

Option (c) is given as “phallus”

The phallus is a mimetic object that resembles the penis, a male secondary sexual organ. It is an external object and not a natural organ system. So, the phallus has nothing to do with the mesonephric duct. Hence, it is wrong answer.

Option (d) is given as “labioscrotal folds”

The labioscrotal folds are the paired structures in the human embryo that gives rise to the external genitals in both females and males. In females, the labioscrotal folds give rise to labia major in the vagina, and in the males it gives rise to the scrotum to hold the testes. Hence, it is wrong answer.

Option (e) is given as “urogenital fold”

Urogenital folds give rise to labia minor, an external genitalia in females. Hence, it is wrong answer.

Hence, options (b), (c), (d), and (e) are incorrect.

Conclusion

Mesonephric duct gives rise to the ductus deferens in the males, which acts as a carrier transport of semen during an ejaculation.