Fertilization and embryo transfer
Embryo cultivating
For oocyte fertilization the fresh husband's sperm is required on the day of the egg retrieval. Sperm is delivered by means of masturbation. Sometimes sperm may be collected in advance and kept in the laboratory at a very low temperature (sperm cryopreservation). It is not always possible to deliver sperm "on request" due to emotional stress. Such issues can be identified, discussed and resolved in advance.
The sperm must be processed by the laboratory before fertilization to optimize the fertilization capacity of the spermatozoa. The oocytes and spermatozoa are cultivated in a-nutrient medium for the next 24 hours.
The morning after the oocytes have been collected our specialists in the IVF laboratory check to see if fertilization has occurred. There are two pronuclei in a fertilized ovum, one is from the sperm and one is from the oocyte. Within a few hours, the pronuclei join together and form the nucleus of the cell. The nucleus contains the chromosomes, which contain the genes that determine the genotype.
The fertilized oocytes continue to be cultivated in an incubator where the temperature and amount of carbon dioxide are carefully regulated. By the following morning the oocytes have divided and they are now referred to as embryos. The embryos are classified based on the amount of cells they have and the quality of their structure. The best embryos are chosen to be transplanted and the rest of the good embryos may be frozen.
Fig. 1. Embryo transfer
Embryo transfer is a simple and painless procedure implemented on the 3rd day after the oocyte retrieval. In some cases the
procedure is made on the 5th day. The embryo is transfered using a very thin soft plastic catheter which is introduced into the uterus
via the vagina and cervical canal. In our practice we transfer only one or two embryos, to avoid muliple pregnancies.
