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Compared to a blastocyst biopsy, a polar body biopsy can potentially be of lower costs, less harmful side-effects, and more sensitive in detecting abnormalities. [38] The main advantage of the use of polar bodies in PGD is that they are not necessary for successful fertilisation or normal embryonic development, thus ensuring no deleterious ...
In current state of the art, early embryos having undergone cryopreservation implant at the same rate as equivalent fresh counterparts. [2] The outcome from using cryopreserved embryos has uniformly been positive with no increase in birth defects or development abnormalities, [3] [8] also between fresh versus frozen eggs used for intracytoplasmic sperm injection (ICSI). [9]
After the somatic cell transfers, the cytoplasmic factors affect the nucleus to become a zygote. The blastocyst stage is developed by the egg to help create embryonic stem cells from the inner cell mass of the blastocyst. [3] The first mammal to be developed by this technique was Dolly the sheep, in 1996. [4]
The duration of embryo culture can be varied, conferring different stages of embryogenesis at embryo transfer.The main stages at which embryo transfer is performed are cleavage stage (day 2 to 4 after co-incubation) or the blastocyst stage (day 5 or 6 after co-incubation).
Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. [5] Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. [1]
This would mean that for a typical rate of 31% in clinics that use early cleavage stage cycles, the rate would increase to 32% to 41% live births if clinics used blastocyst transfer. [47] Recent systematic review showed that along with selection of embryo, the techniques followed during transfer procedure may result in successful pregnancy outcome.
The blastocyst is still enclosed in the egg-coat known as the zona pellucida, and for it to be able to implant into the uterine wall it must rid itself of this covering. This stage is known as zona hatching, and when there is sufficient dissolution the blastocyst is able to initiate the apposition stage of implantation.
To begin transcription of zygotic genes, the embryo must first overcome the silencing that has been established. The cause of this silencing could be due to several factors: chromatin modifications leading to repression, lack of adequate transcription machinery, or lack of time in which significant transcription can occur due to the shortened cell cycles. [7]