This MCQ module is based on: Male Reproductive System
Male Reproductive System
This assessment will be based on: Male Reproductive System
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Chapter 2 — Human Reproduction (Part 1): The Male Reproductive System
Humans are and . Reproductive events in human male and female include the formation of gametes (gametogenesis), insemination, fertilisation, implantation, embryonic development, and parturition (childbirth). In this part, we explore the structure and function of the male reproductive system.
3.1 The Male Reproductive System
The male reproductive system is located in the pelvis region. It consists of a pair of , accessory ducts, accessory glands, and the external genitalia.
3.1.1 The Testes
The testes are situated outside the abdominal cavity within a pouch called the . The scrotum maintains the temperature of the testes at about 2-2.5 °C lower than the normal internal body temperature, which is necessary for .
Each testis is oval in shape, about 4-5 cm long and 2-3 cm wide. It is covered by a dense covering. Internally, each testis is divided into about 250 compartments called testicular lobules. Each lobule contains one to three highly coiled in which sperms are produced.
3.1.2 Inside the Seminiferous Tubule
Each seminiferous tubule is lined on its inside by two types of cells:
- Male germ cells (): These divide and differentiate to form sperms.
- : These provide nutrition to the developing germ cells.
The regions outside the seminiferous tubules, called interstitial spaces, contain small blood vessels and groups of . Leydig cells synthesise and secrete testicular hormones called androgens, principally . Other immunologically competent cells are also present in the interstitial space.
3.1.3 Accessory Ducts
The male sex accessory ducts include the rete testis, vasa efferentia, epididymis and vas deferens. The seminiferous tubules of the testis open into the through rete testis. The vasa efferentia leave the testis and open into the located along the posterior surface of each testis.
The epididymis leads to the that ascends into the abdomen and loops over the urinary bladder. It receives a duct from the and opens into the urethra as the ejaculatory duct. These ducts store and transport the sperms from the testis to the outside through the urethral opening.
The originates from the urinary bladder, extends through the penis to its external opening called the urethral meatus.
3.1.4 The Penis
The is the male external genitalia. It is made up of special tissue (erectile tissue) that helps in erection of the penis to facilitate insemination. The enlarged end of the penis called the glans penis is covered by a loose fold of skin called the foreskin.
3.1.5 Accessory Glands
The male accessory glands include paired seminal vesicles, a single prostate, and paired bulbourethral glands. Their secretions together with sperms form the . The secretion of the bulbourethral glands also helps in the lubrication of the penis.
| Accessory Gland | Number | Secretion / Function |
|---|---|---|
| Seminal vesicles | Pair | Fructose-rich fluid for sperm energy; contributes ~60% of semen volume. |
| Prostate gland | Single | Slightly alkaline secretion that activates sperm and neutralises vaginal acidity. |
| Bulbourethral (Cowper's) glands | Pair | Lubricating mucus secretion; aids penile lubrication during coitus. |
3.1.6 Hormonal Regulation
Hormonal regulation of the male reproductive system involves the hypothalamus, anterior pituitary and the testis. The hypothalamus releases GnRH (Gonadotropin Releasing Hormone) which acts on the anterior pituitary to release two gonadotropins:
- : acts on Sertoli cells and stimulates secretion of factors that help in spermiogenesis.
- : acts on Leydig cells and stimulates synthesis and secretion of androgens (mainly testosterone).
Androgens then stimulate the process of spermatogenesis. They also regulate the development, maturation and functions of the male accessory sex organs and the expression of male secondary sexual characters (deepening of voice, growth of facial and body hair, muscle development, etc.).
Interactive: Male Hormone Pathway Explorer
Click each pathway step to see the hormone and its target.
3.1.7 Worked Examples
Example 1 — Why are testes located outside the abdominal cavity?
Answer: The scrotum maintains the testes at about 2-2.5 °C below normal body temperature. This lower temperature is essential for the normal process of spermatogenesis. At core body temperature, sperm production is impaired, which is why retention of testes inside the abdomen (cryptorchidism) leads to sterility.
Example 2 — Function of Sertoli cells vs Leydig cells
Answer: Sertoli cells lie inside the seminiferous tubules and provide nutrition to developing germ cells; they are stimulated by FSH and secrete inhibin. Leydig cells (interstitial cells) lie outside the seminiferous tubules in the interstitium; stimulated by LH, they secrete androgens (mainly testosterone) responsible for spermatogenesis and male secondary sexual characters.
Example 3 — Trace the path of sperm from formation to release
Answer: Seminiferous tubule → Rete testis → Vasa efferentia → Epididymis (maturation/storage) → Vas deferens → joins duct of seminal vesicle to form Ejaculatory duct → Urethra → Urethral meatus.
Activity 3.1 — Build the Male Reproductive Pathway
Predict: Arrange the following structures in the correct order from sperm formation to release: Vas deferens, Urethra, Seminiferous tubule, Epididymis, Ejaculatory duct, Rete testis, Vasa efferentia.
Observe: Seminiferous tubule → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra.
Explain: Sperms are formed in the seminiferous tubules, mature in the epididymis (giving them motility), and are propelled through the vas deferens during ejaculation. The vas deferens joins the seminal vesicle duct to form the ejaculatory duct, which empties into the urethra for delivery via the penis.
Competency-Based Questions
(a) Sertoli cells (b) Spermatogonia (c) Leydig cells (d) Mast cells
Assertion–Reason Questions
Choose: (A) Both A and R are true and R is the correct explanation of A. (B) Both A and R are true but R is NOT the correct explanation of A. (C) A is true, R is false. (D) A is false, R is true.
Reason (R): Spermatogenesis requires a temperature 2-2.5 °C below normal body temperature.
Reason (R): Leydig cells are found inside the seminiferous tubules.
Reason (R): Cutting the vas deferens prevents sperms from entering the ejaculate.