Cytogenetic analysis of sperm nucleous components of iranian normal and sub-fertile individuals using zona free hamster oocytes

Abstract

Purpose: The purpose of this study was to investigate whether infertility is affected by sperm chromatin and cytogenetic abnormalities. To this purpose, the frequency of sperm premature chromosome condensation (PCC) induction and numerical chromosome abnormalities in the sperm of normal and sub-fertile men were analyzed. PCC rate was studied for evaluating the role of sperm chromatin abnormalities in the process of nuclear decondensation.

Design: Controlled prospective study.

Setting: Infertility Genetics Department, Royan Institute.

Patient: Sub-fertile males who were referred for infertility treatment and sperm cytogenetical studies.

Methods: Hamster oocytes were retrieved after super ovulation by PMSG and HCG injection. Following treatment with Hyaloronidase, zona was removed by trypsin digestion. Sperms were classified according to the morphology, movement and counts and then processed by swim up method. After capacitation, zona-free oocytes were incubated with sperms, and then transferred to fresh media containing colcemid. Slides were prepared using Tarkowskie's standard air-drying technique. Oocytes were analyzed using x 1000 microscope after staining in 5% of Giemsa.

Main outcome measure: The incidence of sperm aneuploidy, PCC and penetration rate in three groups were determined.

Results: Regarding the PCC rate, a significantly higher frequency was found in infertile patients. (P < 0.001). The frequency of PCC in oligosperm samples was 36% compared to 19.37% in normal group. A higher frequency of numerical chromosome abnormalities was found in infertile patients. The rate of these abnormalities was 5.6% in normal group and 18.5% in oligospermic samples. Despite the considerable difference between those frequencies, this difference is not significant. (P > 0.05).

Conclusions: From the results it can be concluded that, formation of sperm PCC is a major cause of failed fertilization in individuals with sperm abnormalities. PCC may form due to chromatin abnormalities, improper DNA packing, chromosomal abnormalities and penetration delay of sperm. Also this may be involved in the etiology of some cases of idiopathic infertility. About numerical chromosome abnormalities although the differences are not significant, there is an association between sperm numerical chromosome abnormalities and male infertility. These abnormalities can be originated from meiotic process in spermatogenesis.