Y chromatin frequency in white blood cells of newborn males

The frequency of fluorescent Y chromatin bodies was studied in white blood cells of 30 newborn males during the first 5 days of life. No significant day-to-day changes were observed within the neonatal period (Tab. I). This finding indicates that the changes of both X and Y chromatin frequency reported previously for buccal mucosa cells of newborn infants have no profound biological significance, and that they are due to the condition of buccal mucous cells in the neonatal period which renders these cells less suitable for sex chromatin determination.