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Submitted by Dr. Hesham Al-Inany, M.D. Lecturer, Gynaecology & Obstetrics dept. Kasr El-Aini hospital, Cairo University, Egypt.

Micromanipulation
 

During Gamete Micromanipulation sperms are injected into an ovum to assist in union of the gametes.

 
 

 
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Gametogenesis: a basic review
Anomalies of the female genital tract

 
   
 
     

Indications

  • Severe oligospermia

The severely oligospermic patients usually has a combination of multiple spermatozoal defect (WHO, 1987) with poor chances of spontaneous conception. In vitro fertilization (IVF) has not contributed to significant improvement for patients with severe oligospermia (Yovich and Stanger, 1987). Fertilization rates decreases when inseminating concentrations are reduced .
While tubal embryo transfer (Diamond et al, 1986) improves the pregnancy rate following fertilization, the fertilization process still requires the initial semen sample to be more than 5 million/ml (Hamori et al, 1988).

  • Severe multiple sperm factors

Severe forms of oligoasthenoteratozoospermia have very poor prognosis in terms of treatment and realization of pregnancy. There is significant reduction in fertilization in triple sperm defects (35.1%, 61 men in 116 cycles), when compared to single sperm defects (61.3% , 121 men in 206 cycles). Such a combination is to be expected when there is seminiferous tubular failure, usually of an idiopathic nature.
Tubal embryo transfer (TET) otherwise known as pronuclear stage transfer (PROST) and tubal embryo stage transfer (TEST) (Yovich et al, 1988) , does not offer increased hope for patients with severe sperm problems as the spouses' oocytes still need to be fertilized before transfer into the fallopian tubes. Such patients have previously relied on artificial insemination with donor sperm. Now, micro-insemination offers some hope (Ng et al,1991).

  • Immotile sperm

Motility has an important influence on fertilization rates (Bongso et al, 1989). Immotile spermatozoa may be caused by enviromental or congenital factors e.g ciliary dyskinesis. Enviromental problems, e.g drug therapy, usually result in decreased motility, and this can be improved by removal of the drug or introduction of additives into the sperm washing procedures (Bongso et al, 1989).
Congenital problems are more difficult to treat and there is the ethical issue of whether propagation of such genes is desirable or not.

  • Inability to penetrate egg vestments

Chia et al (1984), reported unexplained failed fertilization inspite of oocytes being mature and spermatozoa of good motility.
The zona-penetration test (Overstreet, 1983) may shed more light on this defect. The hemi-zona assay will help in the understanding of sperm penetration through the zona (Burkman et al, 1988).
Spontaneous hardening of the ZP has been described in mouse oocytes cultured in vitro after increasing resistance to solubilization by chemotrypsin.
Alterations of the surface structure of the zona have been linked to sperm-binding capacity of the zona . Previous failed attempt of IVF in such condition is necessary proceeding to gamete micromanipulation (Ng. et al, 1990).
Specific sperm abnormalities that do not allow attachment of sperm to oocyte, e.g acrosomeless sperm might also justify sperm injection directly without IVF trials. (Lalonde et al, 1988).

Limitations

There are limitations to the widespread application of micro-insemination. It requires expensive equipment and training, time consuming, and currently yields low fertilization rates. It is still a research procedure and optimal conditions for its successful application are still not determined (Ng. et al, 1991)

Contraindications

The absolute contraindication is a genetic abnormality in the male. There have been no reported studies on the sperm chromosomes of oligospermic men . It is unlikely to have an increased abnormality in sperm haploid chromosomes when the peripheral karyotype is normal (Ng et al, 1990).
Peripheral karyotype of the male is highly recommended in any program of gamete micromanipulation. The incidence of sperm chromosome aberrations from proper donors varies between 6.6% and 14.3% (Templade et al, 1988).

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