CHANGES IN VOLUME, SURFACE ESTIMATE, 3-DIMENSIONAL SHAPE AND TOTAL NUMBER OF NEURONS OF THE HUMAN PRIMARY VISUAL-CORTEX FROM MIDGESTATION UNTIL OLD-AGE
G. Leuba et R. Kraftsik, CHANGES IN VOLUME, SURFACE ESTIMATE, 3-DIMENSIONAL SHAPE AND TOTAL NUMBER OF NEURONS OF THE HUMAN PRIMARY VISUAL-CORTEX FROM MIDGESTATION UNTIL OLD-AGE, Anatomy and embryology, 190(4), 1994, pp. 351-366
Macroscopic features such as volume, surface estimate, thickness and c
audorostral length of the human primary visual cortex (Brodman's area
17) of 46 human brains between midgestation and 93 years were studied
by means of camera lucida drawings from serial frontal sections. Indiv
idual values were best fitted by a logistic function from midgestation
to adulthood and by a regression line between adulthood and old age.
Allometric functions were calculated to study developmental relationsh
ips between all the features. The three-dimensional shape of area 17 w
as also reconstructed from the serial sections in 15 cases and correla
ted with the sequence of morphological events. The sulcal pattern of a
rea 17 begins to develop around 21 weeks of gestation but remains rath
er simple until birth, while it becomes more convoluted, particularly
in the caudal part, during the postnatal period. Until birth, a large
increase in cortical thickness (about 83% of its mean adult value) and
caudorostral length (69%) produces a moderate increase in cortical vo
lume (31%) and surface estimate (40%) of area 17. After birth, the cor
tical volume and surface undergo their maximum growth rate, in spite o
f a rather small increase in cortical thickness and caudorostral lengt
h. This is due to the development of the pattern of gyrification withi
n and around the calcarine fissure. All macroscopic features have reac
hed the mean adult value by the end of the first postnatal year. With
aging, the only features to undergo significant regression are the cor
tical surface estimate and the caudorostral length. The total number o
f neurons in area 17 shows great interindividual variability at all ag
es. Mo decrease in the postnatal period or in aging could be demonstra
ted.