Normal volume of adult testis-
**Core Concept**
The testis is a vital component of the male reproductive system, responsible for producing sperm and testosterone. The normal volume of the adult testis is an essential parameter in the evaluation of male fertility and the assessment of potential testicular pathologies.
**Why the Correct Answer is Right**
The normal volume of an adult testis is approximately 15-20 mL, which is roughly the size of a small egg. This volume is crucial in the clinical assessment of testicular function and pathology. The testicular volume is often measured using a Prader orchidometer, a tool that consists of a series of ellipses of increasing size. The correct volume is essential in distinguishing between normal and abnormal testicular development or function.
**Why Each Wrong Option is Incorrect**
* **Option A:** 5 mL is too small for an adult testis, and such a low volume may indicate testicular atrophy or hypoplasia.
* **Option B:** 50 mL is excessively large for an adult testis, and such an oversized volume may suggest a testicular tumor or other pathological conditions.
* **Option C:** 10 mL is below the normal range, and a testis of this volume may indicate testicular hypoplasia or atrophy.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that testicular volume is an important indicator of testicular function and fertility. A low testicular volume may be associated with hypogonadism, infertility, or testicular atrophy, while an excessively large volume may suggest a testicular tumor or other pathological conditions.
**Correct Answer:** D. 20 mL.