Fertilization of human oocytes in vitro by spermatozoa from oligozoospermic and normospermic men

Sperm were isolated from the semen of oligozoospermic (less than 20 x 10(6) sperm/ml) and normospermic (greater than or equal to 20 x 10(6) sperm/ml) men in an in-vitro fertilization (IVF) programme. Oocytes from the female partners were inseminated with either 75 or 100 x 10(3) motile sperm and checked for fertilization after 16-20 h. A significant reduction in the overall fertilization rate of oocytes was seen for the oligozoospermic group compared to the normospermic group, at both insemination concentrations. In the oligozoospermic group, a fertilization rate of 31% (19/61) was achieved when oocytes were inseminated with 75 x 10(3) sperm, and 38% (9/24) when inseminated with 100 x 10(3) sperm. This compared with rates of 57% (397/696) and 64% (650/1018), respectively, for normospermic cases at both insemination concentrations. No evidence of fertilization was seen in 36% (4/11) and 67% (4/6) of oligozoospermic cases when 75 or 100 x 10(3) sperm were used, compared with values of 13% (17/133) and 9% (20/212), respectively, in normospermic cases. After excluding zero cases, the fertilization rate of oocytes for the oligozoospermic group (75%; 9/12) was similar to the normospermic group (70% 650/935) when 100 x 10(3) sperm were used. However, when 75 x 10(3) sperm were used, the fertilization rate for the oligozoospermic group (41%; 19/46) was significantly lower than that of the normospermic group (62%; 397/645). Following the transfer of embryos into the female partner, clinical pregnancies were diagnosed in 2/7 (29%) oligozoospermic cases and 27/267 (10%) normospermic cases.(ABSTRACT TRUNCATED AT 250 WORDS)