Stages Diameter Time Unfertilized eggs 180 [micro]m 0 sec Sperm attached to egg 185 [micro]m 20-30 sec Sperm acrosome reaction 185 [micro]m ~1 min Sperm-egg membrane fusion 180 [micro]m 2-3 min Appearance of first polar body
185 [micro]m 8-9 min Appearance of second 185 [micro]m 10 min polar body
First cleavage 200 [micro]m 15-20 min Second cleavage 195 [micro]m 35-40 min Morula 200 [micro]m 45-55 min Blastula 192 [micro]m 75-85 min Gastrula 192 [micro]m 85-90 min Trochophore larvae 210 [micro]m 90-250 min Early veliger 225 [micro]m 5-24 h Late veliger 228 [micro]m 28-40 h Early creeping larvae 230 [micro]m 48-72 h Creeping larvae 300 [micro]m 3-6 days Juvenile 2 [micro]m 30 days
Mechanism of polar body formation in the mouse oocyte: an interaction between the chromosomes, the cytoskeleton and the plasma membrane.
Polar body formation: new rules for asymmetric divisions.
Inseminations involving unexposed eggs and irradiated sperm showed significant decreases in acrosomal integrity, sperm incorporation, polar body formation, pronuclear formation, and first cleavage.
Chromosomal separation leading to first polar body formation was effected only at the highest UVB level (Fig.
The position of the metaphase II spindle cannot be predicted by the location of the first polar body in the human oocyte.
Relationship between meiotic spindle location with regard to the polar body position and oocyte developmental potential after ICSI.
At the everyday clinical level, polar body
CGH is likely to have two more important consequences: first, because the analysis is performed on oocytes and not on embryos, countries like Germany which outlaw embryo analysis and freezing will now have at their disposal a reliable method of preimplantation genetic screening; and second, because the chromosomal status of the transferred embryo can be accurately predicted (with no more than a 10 per cent error rate as found in the ESHRE study), the reduction of multiple pregnancies in IVF by single embryo transfer will become more attractive.
Overall polar body
analysis offers many advantages.