Regarding histology of male reproductive system

Correct Answer: C

Rationale: The correct answer is C because the luminal epithelium of efferent ductules is indeed irregular, which helps in absorption and modification of fluid. A, Leydig cells are located outside the seminiferous tubule. B, Sertoli cells provide nourishment and support to developing sperm cells but do not mature spermatids. D, Contraction of smooth muscle in vas deferens is stimulated by the parasympathetic nervous system, not the sympathetic.

Correct Answer: C

Rationale: The testes originate in the abdominal cavity in a fetus. During development, they descend into the scrotal sac through the inguinal canal. This process is essential for proper sperm production as the scrotal environment provides optimal temperature for sperm development. The other choices are incorrect because the testes do not initially form in the scrotal sac, pelvic cavity, or retroperitoneal space. The correct sequence of descent from the abdominal cavity to the scrotal sac is crucial for normal reproductive function.

Correct Answer: D

Rationale: The correct answer is D because a low sperm count (less than 20 million per ml semen) can lead to infertility as it decreases the chances of successful fertilization. A high sperm count (choice A) is actually beneficial for fertility. Increased acrosomal activity (choice B) can enhance fertilization potential. Normal morphology (choice C) refers to the shape and size of sperm, which is important for fertility but not the primary factor in infertility due to low sperm count. Overall, a low sperm count is the most significant factor in infertility.

Correct Answer: D

Rationale: The correct answer is D: zygote. A zygote is formed when a sperm cell fertilizes an egg cell, resulting in a single cell with a full set of 46 chromosomes. This process is called fertilization and marks the beginning of a new individual. The other choices (A: spermatozoon, B: polar body, C: ovum) are not correct because a spermatozoon is a mature sperm cell with 23 chromosomes, a polar body is a byproduct of meiosis in the female reproductive system and has only 23 chromosomes, and an ovum is an unfertilized egg cell also containing 23 chromosomes.

Correct Answer: A

Rationale: The correct answer is A: labia major. The scrotum in males corresponds to the labia major in females as they both serve as protective structures for the reproductive organs. The labia major in females is analogous to the scrotum in males in terms of function and location. The other choices are incorrect because the labia minor (B) is a smaller structure located inside the labia major, the pudendal cleft (C) refers to the space between the labia major and labia minor, and the mons pubis (D) is a rounded, fatty area located over the pubic bone.