X chromatin and chromosome examination in aged women

X chromatin frequencies were compared between aged, middle-aged and young women and statistically significant decrease in frequency was found in the aged as compared to the middle-aged and the young women. For a subsample of aged women results of chromosome examinations were also available which allowed comparison of the frequencies of X chromatin and monosomy C; no significant correlation emerged. This latter finding indicates that karyotypic analysis is necessary for the determination of monosomy C; and that X chromatin counts from buccal mucosal cells cannot be substituted for the examination of karyotypes.