Physiology: Male reproductive organs

Question 1

Why do testes lie in scortum?

Answer 1

Because testicular temperature has to be lower than body temperature to facilitate sperm production

Question 2

Describe the structure and function of testis

Answer 2

Has fibrous capsule called tunica albuginea surrounding the seminiferous tubules (site of sperm production)

Seminiferous tubules:

• Germ cells = produce sperm
• Sertoli/sustentacular cells = support sperm producing cell + produce inhibin
• Interstitial cells = make testosterone

Testes:
- Testosterone -> sexual char + control spermatogenesis

Question 3

Describe the endocrine control of testicular function?

Answer 3

• GnRH -> produced from hypothalamus
• Gonadotrophins -> FSH and LH from ant pituitary
• Testosterone -> released from testicles

Question 4

Describe spermatogenesis

Answer 4

• Sperm production from primordial germ cells
• Cycle is 64 days
• two phases
  > spermatocytogenesis = clonal expansion and maturation through mitotic and meiotic process
  > Spermiogenesis = differentiation into mature sperm cells
• process starts at puberty

Question 5

Describe the chromosomal division during spermatogenesis

Answer 5

One mitotic division -> spermatogonium to primary (46)
First meiotic divison -> primary spermatocyte to secondary. 2 cells with haploid (23)
Second -> secondary to spermatid (23)
Spermiogenesis -> mature into functional sperm cells

Question 6

What are factors affecting spermatogenesis?

Answer 6

> Medical:

1. Pretesticular: Problem with hormonal control
   - Functional- excessive weight loss, gain
   - Intracranial tumours, cysts, bleed
   - Prolactinoma
   - Medications- opiates, external testosterone, steroids(body building)
   - Genetic- Kallmann’s syndrome
2. Testicular: Problem at site of production
   - Surgery- orchidectomy, orchidopexy
   - STI
   - Mumps orchitis
   - Testicular trauma or torsion
   - Radiotherapy or chemotherapy
   - Genetic- Klinefelter’s (46 XXY), Y-chromosome microdeletion

> Lifestyle/environment

• obesity
• traffic smoke
• use of creams