Fertilization (General Embryology)

Fertilization

1. First Week of
Development

2. FERTILIZATION
•It is the process by which a sperm
units with the ovum.
•Site: It occurs at ampullary part
of uterine tube (outer 1/3 of
uterine tube)
Dr. Sherif Fahmy

3. Sperm & Oocyte
Dr. Sherif Fahmy
Corona
radiata
Zona pellucida
Cell
membrane
Secondary oocyte arrested in
2
nd
meiotic division
Head
Neck
Middle
piece
Tail

4. Mechanism of Fertilization
•1-Capacitation of the sperms.
•2-First acrosomal reaction.
•3-Second acrosomal reaction.
•4- Cortical & zona reaction.
•5- Nucleus of sperm enters the cytoplasm of
ovum.
•6- Secondary oocyte completes 2
nd
meiotic
division
•7- Union between male and female pronuclei
to Form zygote.
Dr. Sherif Fahmy

5. FERTILIZATION
Dr. Sherif Fahmy

6. Dr. Sherif Fahmy
Corona
radiata
Zona
pellucida

7. Dr. Sherif Fahmy

8. Start of cortical reaction when the head of sperm starts penetration
of ovum cell membrane
Dr. Sherif Fahmy

9. Dr. Sherif Fahmy

10. Results of Fertilization
•Formation of zygot.
•Restoration of diploid number (46
chromosomes).
•Determination of sex.
•Cleavage (segmentation) starts, during
which the zygote travels through
uterine tube by help of cilia and
contraction of uterine tube.
Dr. Sherif Fahmy

11. Dr. Sherif Fahmy

12. Dr. Sherif Fahmy

13. 2- Cell Stage
Dr. Sherif Fahmy
Zona
pellucida

14. Artificial Fertilization:
- In vitro fertilization: Outside uterus
in culture media.
- Intracytoplasmic sperm injection.

15. Cleavage &
Migration
(Page 14)

16. START OF CLEAVAGE
•Fertilization leads to formation of a zygote which is
a fertilized ovum surrounded with zona pellucida.
•Zygote divides by mitotic division to form 2-cell
stage----- 4-cell stage -------- 8-cell stage ------- 16-
cell stage --------- 32-cell stage ------ 64-cell stage
(morula).
•Cells of morula are called blastomeres.
•Formation of morula takes 3 days through which it
is transmitted through the uterine tube.
•Zona pellucida prevents adhesion of zygote to
uterine tube and prevents separation of cells.
Dr. Sherif Fahmy

17. Dr. Sherif Fahmy

18. Dr. Sherif Fahmy

19. Dr. Sherif Fahmy

20. Dr. Sherif Fahmy

21. Dr. Sherif Fahmy

22. Dr. Sherif Fahmy