I. H. M. Smart

TL;DR: The internal changes within a developing gyrus of the ferret cerebral cortex were studied by recording the changing length and direction of the radial tissue lines and the emergence of the tangential banding of the classical six cortical layers, suggesting that a gyrus was initiated by an area of local growth appearing in the subplate and then in the suprajacent segment of cortical plate.

TL;DR: The external features of gyrus formation in the postnatal ferret cerebral cortex are described and correlated with certain internal changes, which indicate that gyri are formed by longitudinal and radial expansion of the cortical compartment occurring between relatively fixed areas which form the sulcal floors.