--Ricki Lewis
Equality between the sexes is nonexistent when it comes to meiosis. While a male germ cell spawns four equal-size sperm, the female counterpart instead jettisons three of the four nuclei resulting from the two meiotic cell divisions into tiny polar bodies, maximizing supplies stuffed into the egg. A technology called polar body biopsy probes polar bodies for nuclear genes, then infers whether a disease-causing mutant gene has wound up in the egg. Researchers at McGill University and the University of Leeds can detect mitochondrial DNA (mtDNA) in polar bodies (D.A. Briggs et al., "Amplification of DNA sequences in polar bodies from human oocytes for diagnosis of mitochondrial disease," Lancet, 355:1520-1, Apr. 29, 2000.) "It is relatively easy to aspirate the first polar body, produced before fertilization, or the second polar body, after fertilization," says Roger Gosden, research director in the department of obstetrics and gynecology at McGill. ...
