A - ZYGOTES - PRONUCLEI QUALITY
 
(17-19h after insemination)
Normal fertilized oocyte displays 2 polar bodies outside of oocyte and 2 pronuclei inside of.
Z1 et Z2 could give the best embryos.
Z-Score (Scott et All)
Nuclei position in pronuclei.
B - EMBRYOS QUALITY
Development timing
- 2 cells* : 24 hours after insemination
insémination (Day 1)
- 4 cells* : 48 hours (Day 2)
- 8 cells* à 72 hours (Day 3)
- Morula* : (Day 4)
- Expansed blastocyst* (Day 5-6)
* approximative time range, cell = blastomere
NORMAL (typic) AND ABNORMAL (atypic) EMBRYOS
 |
 |
 |
 |
 |
| Typic 2 Cells |
Typic3 Cells |
Typic 4 Cells |
Typic 5 Cells |
Typic 6 Cells |
 |
 |
 |
 |
 |
| Typic7 Cells |
Typic 8 Cells |
Atypic 2 cells |
Atypic3 cells |
Atypic4 cells |
| |
|
 |
 |
 |
| |
|
Fragm. < 10% |
Fragm. > 10% |
Fragm. > 50% |
|
Day 5 : Blastocyst formation (1):
Day 6 : Human blastocyst escaps from its zona pellucida (2)
The blastocyst culture and day 5 embryo transfer procedure for in vitro fertilization facilitates selection of the best quality embryos for transfer to the uterus of the mother.
C - BLASTOCYST QUALITY (According Gardner and All.)
Best blastocysts:
1AA : Blastocoel cavity less than half the volume of the embryo
- Many cells, tightly packed - Many cells, forming a cohesive layer
2AA : Blastocoel cavity more than half the volume of the embryo
- Many cells, tightly packed - Many cells, forming a cohesive layer
3AA : Full blastocyst, cavity completely filling the embryo
- Many cells, tightly packed - Many cells, forming a cohesive layer
4AA : Expanded blastocyst, cavity larger than the embryo, with thinning of the shell - Many cells, tightly packed - Many cells, forming a cohesive layer
------------------------------------------------------------------------
4BB : Expanded blastocyst, cavity larger than the embryo, with thinning of the shell - Several cells, loosely grouped - Few cells, forming a loose epithelium
4CC : Expanded blastocyst, cavity larger than the embryo, with thinning of the shell - Very few cells - Very few large cells
-------------------------------------------------------------------------
Legend :
First number : Blastocyst development and stage status.
First letter : Inner cell mass quality
second letter : Trophectoderm quality
D - EMBRYO TRANSFER
With the progress made in the treatments of assisted reproduction, implantation and pregnancy rates have increased. This evolution has led to increase the rates of multiple pregnancies in the general population.
Considering maternal and fetal risks related to multiple pregnancies it seemed necessary to reduce the number of transferred embryos : 1 or 2 for a young woman and 3 for forty year old woman or more.
Embryo transfer is a simple procedure that does not require anaesthesia.It may be done between D2 (4cell), D3 (6-10 cells)
or D5 (blastocyst) under echography control or not.
Abdominal ultrasound can be used simultaneously to watch the catheter tip advance to the good location
The selected embryos are inserted into a catheter and guided towards the woman’s uterus.
Any additional healthy fertilized embryos can be frozen the same day and used later.
Between D1 and D8 after transfer it is not unusual to see vaginal blood spotting prior to the pregnancy test without consequence for the pregnancy. |
