Deficiency in Fertilization

Fertilization rate will be high when the quality of sperm and oocyte are of good quality. Fertilization rates may be low due to advanced female age and when the quality of the oocyte is structurally poor. The condition defined as ‘fertilization’ is the state where half-chromosomes (23 chromosomes each) of a female and a male come side by side in the oocyte cell. The resolution of these chromosome coils (including male’s), bringing them side by side and mating, increasing the cell number by dividing always happen with the help of mechanisms of the oocyte. In a poor quality oocyte, the risk of not being able to obtain the result is high.

What Is Insufficient Fertilization, How Is It Overcome?

On the other hand, fertilization rate decreases in some specific cases due to sperm structure. The major procedures used in this group are microinjection procedures performed with nonmotile sperms. It is obvious that a motile sperm is alive and has a potential to fertilize the oocyte. A nonmotile sperm is nonmotile because it is dead or paralyzed. A paralyzed but living sperm can fertilize the oocyte. However a dead sperm will not fertilize the oocyte. The difficulty here lies in the fact that it cannot be understood whether the nonmotile sperm is alive or dead. Although there are several tests to differentiate that, the sensitivity is low.

Another characteristic of sperm that causes problems with fertilization is ‘Globozoospermia’. It is caused by a structural, enzyme deficiency in the head portion of sperm. Because of that, sperm cannot hold onto, drill through, get in and fertilize oocyte. Unfortunately, the results are similar for microinjected, in other words injected globozoo sperms into the oocyte. In these cases, the sperms that have a normal structure are collected as much as possible and the procedure is carried out with them. While it is very possible to obtain successful results and to achieve pregnancy in men with low rate of globozoospermia, it is difficult to obtain good results in men with high rates of globo, even if the procedure is carried out with sperms that have normal structure.

The fertilization rate is also low in microinjection procedures carried out with sperms that have a short, thick and curly tail. It is interesting that the tail abnormalities also affect the fertilization although the head portion, in which the chromosome is present, is normal or nearly normal.

Another group is the cases where sperm is very normal in terms of shape and motility, but a low fertilization rate is obtained after the procedure. Since there is no cautionary sign in such cases, they are usually diagnosed later in the laboratory. And probably, the reasons for not being able to get pregnant spontaneously depend on that. Because no fertilization occurs inside the body.

If any indication of miscarriage is known in advance, it is possible to fix it by using some substances. Substances such as Ca ionophore, strontium etc. are added to the oocyte feeding medium of these patients, or piezzoelectric is applied. It is also cautionary to obtain low fertilization rates in a previous IVF treatment.