Gametogenesis is the process by which organisms produce gametes (reproductive cells). In humans, gametogenesis occurs through meiosis in the gonads to produce either sperm or eggs with half the number of chromosomes. Spermatogenesis is the process where special somatic cells in the testes undergo meiosis and maturation to form sperm. During oogenesis in females, follicles in the ovaries develop through the ovarian cycle, with one follicle undergoing maturation and ovulation to release an egg. If fertilization occurs, the remaining follicle forms the corpus luteum to secrete progesterone. The uterine cycle is regulated by hormones and involves the menstrual, proliferative, and secretory phases. It prepares the uterus for potential implantation

1. Gametogenesis
Physiology of reproductive system
Ms. Beatriz Duro 3º ESO

2. Human genetic material
• DNA is a large molecule
which coils up into a
structure called
chromosome when the
cell is about to divide.
– When the cell is not
dividing it is loose in the
nucleus in the form of
chromatin.
• DNA contains the genetic
information which
controls cell processes.

3. Human genetic material
• All human somatic
cells have 46
chromosomes (23
pairs).
– Diploid cells: cells with
pairs of chromosomes.
• Gamets have 23
chromosomes in total.
– Haploid cells: cells with
only one chromosome
of each type.
This is the
human
karyotype

4. Human cell division
Somatic cells (2n) divide
to form two identical cells
(2n) of the same kind
through mitosis
A special somatic cell (2n)
divides to form four cells
with half the genetic
material (n) through
meiosis
2 types of cell
division:

5. Spermatogenesis
Growth and
replication of DNA
Meiosis
Maturation

6. Spermatogenesis
• Maturation
– Takes place in the
epididymis.
– The cell elongates.
– The cytoplasm is reduced.
– The nucleus is set at the
front of the cell together
with the acrosome.
– The flagellum is formed.

7. Male gamet: sperm

9. Female gamet: ovum

10. Oogenesis

11. Ovarian cycle
Follicular
phase
Caused by the secretion of FSH by the pituitary gland.
Lasts 14 days
Various follicles begin to develop, however only one matures
Ovulation The ovum is released by the ovary.
Cause by the presence of LH
The body temperature increases 0.5ºC
Luteal
phase
The area where the ovum was, tranforms into a mass of cells: corpus luteum.
Corpus luteum secretes progesterone for 10-12 days.
When it stops secreting hormone the cycle begins again.

12. Begining of the
cycle.
Sharp decrease in
the amount of
hormones secreted
by the ovaries.
Vascularized uterine
wall is shed and
expelled from the
body: period.
Lasts 4-5 days
Menstrual
phase (Period)
Uterine wall is rebuilt
thanks to estrogens
produced by the
ovaries.
Lasts 11 days.
Proliferative
phase
Uterine lining is at its
maximum thickness,
ready to receive
fertilised egg.
Due to the
progesterone
secreted by the
ovaries.
Lasts 12 days if
fertilization does not
occur
Secretory
phase (Luteal)
Uterine cycle

13. Menstrual and Ovarian cycles