Lesson 3: Spermatogenesis

Question 1

Gamete Formation -
Sperm

Answer 1

This process is called
spermatogenesis

Takes place in the testes of
the male

The final product is 4
haploid sperm cells

Each sperm cell has the
same number of
chromosomes and the same
amount of cytoplasm

Question 2

Spermatogenesis

Answer 2

Sperm production and development occurs in the
seminiferous tubules.

Each tubule is enclosed in a basement
membrane beneath which is a layer of
germinal epithelium cells known as
spermatogonia

The germinal epithelium cells are diploid and
divide (mitosis) regularly to produce more
diploid cells which enlarge and are known as
primary spermatocytes.
Primary spermatocytes
divide by meiosis.

The first meiotic division
produces two haploid
cells called secondary
spermatocytes.

The second meiotic
division of the
secondary
spermatocytes produces
four spermatids.

Question 3

Sperm Development

Answer 3

Spermatids attach to Sertoli cells,
also called nurse cells.

Sertoli cells assist in the
differentiation of immature
spermatids into spermatozoa by
providing nourishment.

Once the spermatozoa have
developed their tails, they detach
from the Sertoli cells and are carried
down the lumen of the tubule to the
epididymis.

Sperm maturation and storage occurs
in the epididymis.

Question 4

Hormones and Sperm Production

Answer 4

Sperm production is controlled by three hormones

Follicle – Stimulating Hormone (FSH) – stimulates meiosis in
spermatocytes, to produce haploid cells

Testosterone – stimulates the maturation of secondary spermatocytes into
mature sperm cells

Luteinising Hormone (LH) – stimulates the secretion of testosterone by
the testes.

Question 5

Semen

Answer 5

Sperm cells are released at ejaculation in a nutrient – rich fluid known as
semen.

Semen is produced by the two seminal vesicles and the prostate gland.

70% of semen is fluid from the seminal vesicles. It is rich in fructose to
provide energy for the sperm to swim and contains mucus to protect the
sperm from the acidic environment of the vagina.

The prostate gland produces an alkaline fluid

Semen is mixed with sperm cells as they leave the epididymis and move along
the vas deferens (sperm duct)