Male Reproductive Anatomy and Function (Lec 3)

Question 1

Ducts of Male Reproductive System

Answer 1

Sperm delivered to exterior through system of ducts:
Seminiferous tubules → Straight tubules → Rete testis → Efferent ductules → Epididymis → Vas deferens → Ejaculatory duct → Urethra

Question 2

The Testes

Answer 2

Contained within the scrotum. Septa divide testes into 250 lobules with each lobule containing 1-4 semineferous tubules

Question 3

Semineferous Tubules

Answer 3

Site of sperm production, lined by complex stratified epithelium

Question 4

Male HPG Axis

Answer 4

Hypothalamus -> GnRH -> Anterior Pituitary -> FSH + LH…

Question 5

Male HPG Axis: FSH Release

Answer 5

FSH -> Sertoli Cells ->

1. Inhibin -> Anterior Pituitary: inhibits further release of FSH
2. Androgen-binding Protein (ABP) -> Testosterone: binding of ABP and Testerosterone keeps Testosterone levels at a high concentration

Question 6

Male HPG Axis: LH Release

Answer 6

LH -> Leydig Cells ->

1. Testosterone (combined with ABP): Maintains Testosterone levels at correct concentration

Question 7

Cells in the Testes: Semineferous Tubules

Answer 7

Sertoli Cells: nourishment and protection for developing sperm, produce ABP/growth factors, contain receptors to bind Testosterone and FSH
Spermatogonia: develop into Sperm

Question 8

Cells in the Testes: Interstitial Space

Answer 8

Leydig Cells: secrete testosterone in response to LH, Testosterone diffuses into Semineferous tubules
Pertitubular Myoid Cells: perstaltic movement
Capillary cells: of blood vessels

Question 9

Blood Testes Barrier

Answer 9

Separates the testes from the normal circulatory systems of the body through tight junctions between sertoli cells. Prevents blood, foreign particles, bodily fluids from entering the Semineferous tubules and protects from body’s immune system

Question 10

Spermatogenesis

Answer 10

Formation of haploid Spermatids from diploid Spermatogonia. Stem cells enter into Spermatogenesis around every 16 days

Question 11

Spermiogenesis

Answer 11

The remodelling and maturing of Spermatids into mature Spermatozoa through differentiation and nutrient delivering by Sertoli Cells

Question 12

4 Phases of Spermiogenesis

Answer 12

1. Golgi phase
2. Cap phase
3. Acrosome phase
4. Maturation phase

Question 13

Spermatozoa (Sperm)

Answer 13

Consists of:

• Head/Acrosome: enzymatic penetration of egg
• Midpiece: contains mitochondria
• Tail: forward propulsion

Question 14

Sexual Response Cycle: Genital Reflexes

- Erection of Penis

Answer 14

Dilation of penile arterioles and filling of erectile tissues, vasocongestion (tissue engorgement)

Question 15

Sexual Response Cycle: Genital Reflexes

- Emission

Answer 15

Movement of semen to posterier urethra by contraction of prostate, seminal vesicles, vas deferens and bulbourethral glands. Mediated by sympathetic fibres via hypogastric n.

Question 16

Sexual Response Cycle: Genital Reflexes

- Ejaculation

Answer 16

Propulsion of semen out of penis by contraction of smooth muscles of urethra and reflex contraction of bulbospongiosus (pulsatile release)

Question 17

Erectile Tissue

Answer 17

During arousal, nerves in penis release Vasoactive Intestinal Peptide (VIP) and Nitric Oxide (NO)

• Corpus Spongoisum: surrounds urethra
• Corpus Cavernosa: paired dorsile erectile bodies

Question 18

Semen

Answer 18

Contains fructose (ATP), protects/activates sperm, and facilitates sperm movement. Alkaline fluid that neutralizes acidity of male urethra/female vagina and enhances motility

Question 19

Accessory Gland Secretion

Answer 19

Seminal Vesicles: ~65% of seminal fluid, alkaline, prostoglandins, clotting proteins and fructose (ATP)

Prostate: ~30% of seminal fluid, contains enzymes and secretes milky, slightly acidic fluid

Bulbourethral Glands: <5% of seminal fluid, thick, clear mucus to lubricate glans penis, alkaline to neutralize

Question 20

Normal Semen Analysis

Answer 20

Colour: white, opalescent
pH: 7.35-7.50
Volume: 2-6mL
Sperm Count: >40million/mL (sterile if <20mil/mL)