A morphometric analysis of the postanatal development of the choroid plexus epithelium in the male and female rat

Morphometric parameters of the lateral ventricle choroid plexus epithelial cells (average area, perimeter, bounding rectangle area, average nuclear area, nuclear perimeter, nuclear circularity and average nucleocytoplasmic ratio) were studied in postnatal and juvenile (10^th, 16^th and 38^th postnatal days) 15 male and 15 female rats. The results were statistically analyzed by factorial ANOVA.

Mean values of epithelial cells area, bounding rectangle area and perimeter were significantly higher in 16 days old, than in 10 and 38 days old rats. Opposite to this, the nucleocytoplasmic ratio was lower in the 16 days old, than in 10 and 38 days old rats. Average nuclear area and perimeter showed similar trends, while nuclear circularity increased from the 10^th to the 38^th day. Significant sex differences were in the epithelial cells area, bounding rectangle area and perimeter, being higher in males than in females in both 16 and 38 days groups. Nucleocytoplasmic ratio was higher in 10 days old male rats, but lower in 16 and 38 days old male rats.

Generally, choroid epithelial cells size increased on the 16^th and then decreased on the 38^th day, but still remained higher compared to the 10^th day. Nuclear size after increasing on day 16, also decreased on day 38, but to values lower than on day 10. The general decrease of nucleocytoplasmic ratio which accompanied these changes indirectly suggests a functional decrease. In the investigated period the male rat choroid epithelial cells were larger, but their nucleocytoplasmic ratio, which suggests the functional status, was lower than in females, indicating sex differences in the growth dynamics of the rat choroid plexus.