Development of the human mesencephalic trigeminal nucleus: a morphometric study.

Anatomical development of the human mesencephalic trigeminal nucleus was assessed quantitatively and qualitatively, using serial sections of brains, with the help of a computer-assisted image-analyser. Five fetuses at 16, 18, 21, 23 and 27 weeks of gestation; five neonates at 30, 32, 33, 35 and 40 weeks of gestation; a two-month-old infant and a 63-year-old adult were studied. Morphometric analyses of the mesencephalic trigeminal nucleus revealed that orocaudal columnar length and neuronal areas gradually increased with gestational age. Diversity of neuronal areas appeared after 32 weeks of gestation, but neuronal numbers and shapes showed little change throughout prenatal and postnatal life.