Embryo Development and Selection of the Embryos for Transfer

In the first days of test-tube-baby technology, culture media developed for body cells were being used. However, since embryos were different from ordinary body cells, they need different nutrients and growth factors throughout developmental stages. Test-tube-baby technology, which is being improved continuously, gives rise to more suitable and more complicated culture media for the development of embryos. Consequently, pregnancy ratios have been improved compared to the ratios of the past years.

There are many factors affecting the development of embryos. The most important of them are:

• Devices called incubators, in which the embryos are placed in
• Hydrogen ion concentration (pH) of the culture media
• Quality control policy of laboratories
• Knowledge and skills of the embryologists

The development of the embryo can be outlined as follows:

Following the microinjection or test-tube-baby procedures;

	Fertilization is observed after 16-18 hours.
	An embryo is observed with 3-4 cells after 48 hours (2nd day).
	An embryo is observed with 6-8 cells and submerging of cells after 72 hours (3rd day).
	An embryo called morula is observed with 16-20 cells after 96 hours (4th day).
	An embryo called blastocyst is observed with cells more than 60 on the 5th day.

Embryo transfer procedure can be performed on 3^rd , 4^th or 5^th days. The day of transfer is determined according to the characteristics of the embryo and of the case. A hole is produced with laser on the outer walls of the embryos before the transfer in order to improve the chance of holding on.

Embryo transfer procedure is painless and anesthesia is not necessary. The mucus found in the cervix ir removed, and embryos are left within the help of a thin catether. Embryo transferring must be carried out under the guidance of ultrasonography when the bladder is full, in order to know where the embryos are put, and not to touch the inner membrane of the uterus. A bed rest for one hour is advisable after embryo transfer procedure. After that, leaving the hospital with any vehicle is possible.