Male Pelvic Anatomy

Question 1

Scrotum

Answer 1

• External supporting structure for testes
• Consists of loose skin and a subcutaneous layer
• Connected to the root of penis and divided into to compartments to house each teste
• Location and muscle contractions regulate temperature for optimum sperm production

Question 2

Structure of Testes

Answer 2

• Tunica Albuginea - surround each teste, a white fibrous capsule which divides testes into 200+ cone shaped lobules
• Lobules contain: Leydig cells (secrete testosterone), 1-3 seminiferous tubules per lobule, tubules unite to form rete testes - drained by numerous tubules entering the head of the epididymis.
• Tunica vaginalis - derived from the peritoneum, encapsulates the testes and forms during the descent.

Question 3

Spermatogenesis

Answer 3

• Spermatozoa is produced in the seminiferous tubules which are lined with spermatogenic cells.
• Sperm then pass to and are stored in the epididymis

Question 4

Structure of sperm

Answer 4

• Head is nucleus, filled with DNA and enzymes to penetrate ovum.
• Body contains a lot of mitochondria to fuel tail.

Question 5

Horomone Secretion

Answer 5

• Mainly testosterone and some androgen hormone, produced by leydig cells.
• Main function is for the development of secondary sex characteristics
• influence male sexual behaviour, distribution of fat and muscle and of hair.

Question 6

Hormone control and negative feedback

Answer 6

• At onset of puberty, increased secretion of GnRH
• This stimulates secretion of FSH and LH from the pituitary gland
• LH -> testosterone secretion from Leydig cells
• Testosterone act via negative feedback to suppress LH and GnRH.
• At threshold level of spermatogenesis achieved, sertoli cells release inhibin which inhibits FSH secretion

Question 7

Epididymis

Answer 7

• Lies on posterior of each teste
• Approx 4cm long
• Larger head which joing to efferent duct from testes
• Body is narrower
• Tail is smaller and continues as Vas Deferens
• Function: to store and move sperm, provide path for sperm, involved in sperm maturation, secretes some seminal fluid

Question 8

Vas Deferens

Answer 8

• AKA seminal ducts
• posterior to the epididymis and enters pelvic cavity
• 3 muscular layers, outer and innner are longitudinal and middle is circular.
• Function: to convey sperm from epididymis toward urethra during sexual arousal

Question 9

Ejaculatory Ducts

Answer 9

• 2 ducts formed at the union of the vas deferens and ducts of the seminal vesicles
• Enter upper, posterior aspect of the prostate
• Eject sperm and secretions prior to release of semen

Question 10

Seminal Vesicles

Answer 10

• 5cm pouch like structures which secrete an alkaline fluid through seminal vesicle ducts to form 60% of semen.

Question 11

Prostate Structure

Answer 11

• 4cm x 3cm x 2cm
• Size increases slowly until puberty, expands rapidly until 30 sometimes may further enlarge at 45.
• Inf to bladder, surrounds prostatic urethra.
• Composed of 30 small tubule-alveolar glands - a number of ducts open into urethra

Question 12

Prostate Function

Answer 12

• Secretes thin alkaline substance - essentially protects sperm from acidic environments.

Question 13

Bulbourethral Glands

Answer 13

• Inf to prostate
• Pea sized
• Secrete alkaline fluid during sexual arousal

Question 14

Urethra

Answer 14

• 3 Sections
• Prostatic Urethra - passes through the prostate, 2-3cm long, ejaculatory duct enters in this section
• Membranous Urethra - middle section from apex of prostate to bulb of penis - 1cm long

-Spongy (penile) urethra - 10-15cm long

Question 15

Penis

Answer 15

• 3 cylindrical masses of erectile tissue enclosed in fibrous coverings (tunica albuginea)
• Consists of erectile tissue permeated by blood sinuses.