ppt for nursing students to make them easy to understand

1. FERTILIZATION
&
IMPLANTATION
PRESENTED BY:
Ms. Satnam Kaur Mand

2. FERTILIZATION
• Fertilization is the process of fusion of the
spermatozoon with the mature ovum.
• It begins with sperm egg collision and ends
with production of a mononucleated single
cell called the zygote.

3. OBJECTIVES
• To initiate the embryonic development of
the egg.
• To restore the chromosome number of the
species.

5. APPROXIMATION OF GAMETES
• The ovum, immediately following ovulation
is picked up by the tubal fimbriae which
partly envelope the ovary, specially at the
time of ovulation.
• The ovum is rapidly transported to the
ampullary part.

6. CONTI…
• Fertilisable life span of oocyte ranges from 12 to
24 hours whereas that of sperm is 48-72 hours.
• Out of hundreds of millions of sperms deposited
in the vagina at single ejaculation, only thousands
capacitated by muscular contraction and
aspiration action of the uterine tube.
• It takes only few minutes for the sperm to reach
the fallopian tube.

7. CONTACT AND FUSION OF
GAMETES
• Complete dissolution of the cells of the corona
radiata occurs by the action of hyaluronidase .
• Penetration of the zona pellucida is facilitated
by the release of hyaluronidase. More than one
sperm may penetrate the zona pellucida.
• Out of many sperms, one touches the oolema.

8. CONTI..
• Soon after the sperm fusion, penetration of other
sperm is prevented by Zona reaction (hardening).
• Completion of second meiotic division of the
oocyte.
– Bigger one -- female pronucleus
– Smaller one– Second polar body
• Both the head and tail of spermatozoon enter the
cytoplasm of oocyte but membrane is left behind.

9. CONTI..
• Head and neck contains haploid number of
chromosomes (23,X) or (23,Y).
• The male and female pronuclei unite at the
center with restoration of the diploid
chromosomes (46)

11. IMPLANTATION
• Implantation occurs in the endometrium
on the 6th day which corresponds to the 20th
day of a regular menstrual cycle.
• It occurs through 4 stages:
– Apposition (dissolution of zona pellucida)
– Adhesion (attachment between blastocyst and
endometrium)
– Penetration
– Invasion

13. ENDOMETRIUM AT IMPLANTATION
SITE
• Endometrium is in secretory phase
corresponding to 20-21 days of cycle.
• The microvilli on surface interdigitate with
decidual cells to form junctional complexes
• Uterine receptivity and signalling is done
by prostaglandins, progesterone.

14. PENETRATION
• Actual penetration and invasion occurs
through the stromal cells in between the
glands.
• With the lysis of the stromal cells,
blastocyst penetrates inside the decidua
called Intersitial implantation.

15. • .

16. SUMMARIZATION
Today we have discussed about:
• Fertilisation
• Objectives of fertilization
• Fusion of gametes
• Intersitial implantation
• Stages of implantation

17. RECAPTUALIZATION
• What is fertilization?
• What is Fusion of gametes?
• What is zona pellicuda?
• What is Trophoblast?
• What is implantation?
• Stages of Implantation?

18. BIBLIOGRAPHY
• Dutta D.C, Textbook of Obstetrics , 2004,
Sixth Edition, New Central Book Agency(P)
Ltd. Pp 22-27.