X-Chromatin determination in Thai men and women by buccal epithelial cell examination.

X-chromatin determination by Pap smear of buccal epithelial cells of Thais, i.e. 286 normal non-pregnant Thai women, 22 pregnant women and 57 normal Thai men, was made at Siriraj Hospital on cases examined between January 20, 1983 and August 13, 1986. The means and standard deviation of the percentages of X-chromatin were as follows: (a) in the non-pregnant women, 15.0+5.8 (range 2.5-36.5) (of these, 15.0+6.0 were sexually active; 19.2+5.6 were in lactational amenorrhea and 14.3+4.7 were menopausal) and (b) in the pregnant women, 14.0+6.9 (range 5-27). Chromatin-X was not found in the men, but chromocentrum, which is smaller than X-chromatin, was found, the mean chromocentrum being 1.6+1.3 percent (range 0-5).