The incidence of sex chromatin positive nuclei in the buccal mucosa has been studied in 33 full-term newborns (20 females and 13 males) and 45 prematures (26 females and 19 males) on the first 6 days and on the 20th day post-partum. The smears were coded and sex, birth weight and age not revealed to the examiners until the final evaluation of the results. In agreement with the data in the literature, a significantly low percentage of chromatin positive nuclei was found in the full-term females during the first 3 days of life. At the same time the incidence of sex chromatin in the premature females reached, immediately after birth, the average value of adult females and showed no significant change during the following days of life. In both premature and full-term male newborns the percentage of sex chromatin was very low and independent of age. It is concluded that although in everyday practice the sex chromatin examination is generally reliable from the first days of life, it is advisable to repeat it after the 5th day, especially in newborns over 2000 g birth weight.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Developmental Biology