1. The Male Reproductive System
Chapter 48

2. Testes (singular: testis)
Seminiferous tubules – coils of hollow tubes inside each
Testes develop within the body cavity during embryological development but should descend into the scrotum about 2 months before birth
Sperm are produced in the seminiferous tubules and then pass into the epididymis to finish maturation
During ejaculation the sperm travel into the ejaculatory duct, then to the vas deferens and into the body cavity
Then sperm travel through the prostate gland and out of the body through the urethra

3. Spermatogenesis Undifferentiated cells – spermatogonia (diploid)
Mitosis  produce additional spermatogonia
Some spermatogonia enlarge and become primary spermatocytes
Primary spermatocytes undergo meiosis
1st meiotic division  2 secondary spermatocytes (haploid)
2nd meiotic division  4 spermatids
Spermatids  develop into mature sperm
Sperm:
Head
Nucleus covered by the acrosome – contains enzymes which will help it penetrate the egg plasma membrane
Midpiece
Contains mitochondria to provide energy for the flagellum
Tail
Flagellum

4. Accessory glands produce semen
Seminal vesicles – paired
Secrete a nutritive fluid rich in fructose (energy for the sperm) and prostaglandins (stimulate contractions in the uterus to help the sperm move up the female reproductive tract)
Prostate gland – single
An alkaline liquid that helps to neutralize the acidic environment of the vagina
Bulbourethral glands – paired
Release a mucous secretion to lubricate the urethra as well as the vagina

5. From male to female The penis
Tip is the glans – covered by the foreskin which is removed during circumcision
The shaft of the penis has 3 parallel columns of erectile tissue which contain numerous blood vessels
Sexual stimulation dilates arteries and compresses veins, increasing blood flow in and preventing blood flow out, thereby causing erection
Ejaculation releases semen

6. Regulatory hormones: Testosterone
Produced by the interstitial cells between the seminiferous tubules in the testes
Controls the male primary sex characteristics – the growth of the reproductive organs and spermatogenesis
It also stimulates the development during puberty of the secondary sex characteristics – facial and body hair, muscle development, deepening of voice

7. Additional hormones needed
Gonadotropin-releasing hormone
Produced by the hypothalamus
Causes the anterior pituitary to make its sex hormones: follicle-stimulating hormone and luteinizing hormone
These are needed for spermatogenesis and testosterone production