Oogenesis is the process where egg cells, or ova, develop in the ovaries. During fetal development, early egg cells known as primary oocytes form but stop dividing until puberty. Just before ovulation, primary oocytes complete the first meiotic division to form secondary oocytes. Upon fertilization by sperm, secondary oocytes complete the second meiotic division to form a single cell called a zygote containing genetic material from both parents. Fertilization involves sperm undergoing changes to penetrate the secondary oocyte, and the union of the sperm and oocyte nuclei to combine their chromosomes and form a new individual.

1. OOGENESIS AND
FERTILIZATION
Santos, Santuyo, Villena and Dao-
ang
Reporters :

2. OOGENESIS

3. OOGENESIS
OOGENESIS:
- is a type of gametogenesis, which ova, or egg cells, develop
within the tissue of the ovary.
Where the egg
cells developed.

4. PRIMARY OVUM:
- cells that are to become mature ova have been multiplying, and
by the time that the female is born, all of the egg cells that the ovaries will
release during the active reproductive years of the female are already
present in the ovaries.
SECONDARY OVUM:
- it grows in the ovary until it reaches maturation; it then breaks
loose and is carried into the fallopian tubes. Once in the fallopian
tubes, the secondary egg cell is suitable for fertilization by the male
sperm cells.

6. MATURATION OF THE
OOCYTES:
Oogonia give rise to oocytes.
Before, the birth, oogonia
multiply by mitosis. During
development of the fetus, many
oogonia begin meiosis, but stop
in prophase I and are now called
PRIMARY OOCYTES. They
remain in this state until puberty.

7. OOGENESIS Just before ovulation the primary
oocyte completes meiosis
I, creating the secondary oocyte
and a nonviable polar body.
The secondary oocytes begins
meiosis II, but stops at
metaphase II.
During, ovulation, the secondary
oocyte is released from the
ovary.
The secondary oocyte only
completes meiosis II if it is
fertilized by a sperm cell. The
completion of meiosis II forms a
secondary oocyte and a second
polar body. Fertilization is
complete when the secondary
oocyte nucleus and the sperm
cell nucleus and the sperm cell
nucleus unite, creating a

8. Follicle Development

9. Primordial Follicle
 A primary oocyte surrounded
by a single layer of flat cells
called granulosa cells.

10. Primary Follicles
 Enlargement of oocyte and
a single layer of granulosa
cells becomes enlarged and
cuboidal.

11. Secondary Follicle
 Forms when a fluid filled vesicles
develop among the granulosa cells
and well developed theca becomes
apparent around the granulosa
cells.

13. If pregnancy occurs, the corpus
luteum enlarges in response to a
hormones secreted by the placenta
called human chorionic gonadotropin
hormone (HCG).
 If pregnancy does not occur, the
corpus luteum lasts for 10-12 days
and then begins to degenerate.

14. FERTILIZATIO
N

15. FERTILIZATI
ON
Fertilization
is the union of sperm cell and oocyte(secondary), along
with their genetic material (chromosomes) to produce a new
individual.
Process of Fertilization :
1. After sperm cell ejaculated into vagina, they are transported to
the cervix and the body of the uterus to the uterine tubes where
the fertilization occurs.
2. Sperms undergo Capacitation.
• Capacitation
-It makes the sperm cells capable of releasing the
concentrated enzymes contained in the acrosome (a
region of the sperm cell head).
3. The enzymes digest a pathway through the cumulus cells and
zona pellucida of the secondary oocyte.

16. FERTILIZATION
4. The enzymes then digest a pathway through the cumulus cells
and the zona pellucida of the secondary oocyte.
5. Only one sperm cell attaches to the oocyte cell membrane and
enters the oocyte.
6. Subsequently, the secondary oocyte completes the second
meiotic division to form 2 cells, each containing 23
chromosomes.
7. After the second meiotic division, the the oocyte nucleus moves
to the center of the cell, where it meets the nucleus of the
sperm cell.
8. The 23 cells chromosomes from the male then joins with the 23
chromosomes of the females(total 0f 46) forming a ZYGOTE.

17. 4. The zygote divides by mitosis to form 2 cells, which divide to form
4 cells and so on.
5. The mass of cells formed will implant in the uterine wall and will
then develop into a new individual.

18. Many sperm cells come in
contact with the cumulus
cells of the secondary oocyte,
but only one sperm cell will
penetrate the oocyte’s cell
membrane.

19. The head of the
sperm, carrying the genetic
material , enters the
oocyte, which completes the
second meiotic division.

20. The two nuclei fuse to
form a single nucleus.
Fertilization is complete
and a zygote results.