A 30-year-old man consults a gynecologist for the cause of his infeility. On questioning, he informs the doctor that he never suffered from any major illness in the past and also got married 5 years back. However, his physical examination reveals failure of testes to descend down in the scrotum. The semen analysis shows absence of spermatozoa. The blood lab repo shows plasma gonadotrophins, 12 Ru/24 hrs; Plasma testosterone, 7 ug/l and semen 2 ml. The factor responsible for the absence of spermatozoa in this patient is?

**Core Concept**
Testicular descent is a crucial process in male fetal development, and its failure can lead to undescended testes (cryptorchidism). This condition can result in hypogonadism, characterized by low testosterone levels and elevated gonadotropin levels, as the body attempts to compensate for the lack of negative feedback from sex hormones.

**Why the Correct Answer is Right**
In this patient, the failure of testes to descend down into the scrotum (cryptorchidism) is likely responsible for the absence of spermatozoa. This is because the undescended testes are exposed to higher temperatures, which can impair spermatogenesis, the process of sperm production. The elevated plasma gonadotropin levels (12 RU/24 hrs) and low plasma testosterone levels (7 ug/l) further support this diagnosis, as the body attempts to stimulate the testes to produce hormones. The absence of spermatozoa in the semen analysis is a direct consequence of impaired spermatogenesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the underlying cause of the patient's condition. While it may be a possible diagnosis, it does not explain the failure of testes to descend down into the scrotum.

**Option B:** This option is incorrect because it is not directly related to the patient's condition. While it may be a possible cause of infertility, it does not explain the failure of testes to descend down into the scrotum or the absence of spermatozoa.

**Option D:** This option is incorrect because it is not supported by the patient's laboratory results. While it may be a possible cause of infertility, it does not explain the elevated plasma gonadotropin levels or the low plasma testosterone levels.

**Clinical Pearl / High-Yield Fact**
Undescended testes (cryptorchidism) can lead to impaired spermatogenesis, resulting in infertility. It is essential to diagnose and treat cryptorchidism early to prevent long-term complications, including testicular cancer and infertility.

**Correct Answer:** C.

✓ Correct Answer: A. Degeneration of the epithelium of seminiferous tubules