FERTILIZATION & IMPLANTATION.pptx

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.

4. 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.

5. 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.

6. 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 .

7. 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 S maller one– Second polar body Both the head and tail of spermatozoon enter the cytoplasm of oocyte but membrane is left behind.

8. 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 )

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

10. 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.

11. 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.

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

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

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