Prof. Dr. Saeed Shafi : Blastocyst Implantation Prof. Dr. Saeed Shafi Slide 2: Nadia Suleyman, a 32-year old business executive underwent IVF and embryo transfer procedure to combat her primary infertility.
The consultant in Fertility Center advised her Gonadotropins 5-days prior to embryo transfer (ET) into the uterine cavity. Moreover, the Embryologist took blood sample to check her hormonal level prior to ET.
Explain the embryological reason of using therapy in ART. Learning Objectives? : Learning Objectives? Define Blastocyst
Describe the mechanism of its formation
Describe mechanism of implantation Slide 4: Fertilization is a complex sequence of events that begins with contact between a sperm and a secondary oocyte and ends with the intermingling of the maternal and paternal chromosomes at metaphase of 1st cleavage of Zygote. Oocyte & sperm transport : Oocyte & sperm transport Sperm tail motility
Vesiculase in seminal secretions form vaginal plug & prevents backflow of semen into vagina.
At ovulation , cervical mucous become less viscid.
Uterine contractions due to PG in semen
Acid pH of vagina decreases sperm motility
Alkaline pH of uterus increases sperm motility
Chemotaxis by ovum
Secondary Oocyte move by Tubal peristalsis Phases of fertilization : contd. Phases of fertilization Passage of sperm through corona radiata
Hyaluronidase from acrosome
Tubal mucosal enzymes
Penetration of zona pellucida facilitated by
Lysosomal enzymes of cortical granules Slide 7: contd. Fusion of plasma membranes of secondary oocyte and sperm
Completion of 2nd meiotic division of oocyte and formation of female pronucleus
Formation of male pronucleus.
Fusion of pronuclei to form Zygote Slide 8: FERTILIZATION Slide 9: The secondary oocyte completes the second meiotic division, forming a mature ovum and the second polar body. The nucleus of the ovum is known as the female pronucleus.
Once within the cytoplasm of the ovum the tail of sperm degenerates & its head enlarges to form male pronucleus. Ootid & Zygote : Ootid & Zygote The male and female pronuclei come into contact and loose their nuclear envelopes.
The maternal and paternal chromosomes intermingle at equatorial plate of metaphase of the first mitotic division of the zygote. Slide 11: Restoration of diploid chromosomes
Shuffling of genes.
The zygote contains a new combination of chromosomes, different from the parents.
ALLAH forms the bases of biparental inheritance and results in variation of the human species. Results of Fertilization Slide 12: Cleavage
Series of mitotic cell divisions of zygote to form embryonic cells (blastomeres)
Process during which blastocyst attach to endometrium Slide 13: Blastocyst Morula (mulberry)
A ball of 12 – 32 blastomeres SEQUENCE AFTER FERTILIZATION? : SEQUENCE AFTER FERTILIZATION? 1st cleavage after 30 Hours
Blastocyst formation 4th day
Blastocyst floats in Uterus another 2 days
ZP ruptures 6th day
Blastocyst starts implantation 6th day HATCHING OF THE BLASTOCYST : HATCHING OF THE BLASTOCYST Formation of blastocyst (D4)
Shedding of zona pellucida & hatching of the blastocyst (D6)
Differentiation of trophoblasts into cytotrophoblasts and syncitiotrophoblasts
Formation of hypoblasts from embryoblasts Slide 16: Oocyte
Implantation Slide 17: Implantation of Blastocyst Implantation of Blastocyst : Implantation of Blastocyst Day - 4: Morula reaches in uterine cavity
Day - 6: Blastocyst touches endometrium
Day - 8 &9: Progressive implantation
Day - 10: Superficial implantation
Day – 12: Complete implantation
What is closing plug?
When complete regeneration of epithelium of endometrium occurs? Ectopic Implantation sites? : Ectopic Implantation sites? - Placenta previa?
Inhibition of Diethylstibestrol
implantation Abortion pills
- hCG? TAKE HOME MESSAGE : TAKE HOME MESSAGE Signs & sumptoms of ovulation (Biphasic temperature)
Preselection of embryo and peri-implantation diagnosis of genetic disorders!
Sequence of events from Fertilization to implantation!
What is cleavage, morula & blastula?