Age-related classification of pyramidal and stellate cells in the rat visual cortex: a Nissl study with the 'Morphoquant'.

(1) Using Nissl preparations and the automatic picture processing system 'MORPHOQUANT', VEB Carl Zeiss JENA, age-related classification of pyramidal and stellate cells of the layer IV in the rat's visual cortex was performed. (2) 12, 16, 20, 30, 90, and 420 days old animals were investigated. (3) Due to the high cell density and immature stage the neurons of an 8-day-old animal could not be measured. (4) A review is given about the automatic picture processing system 'MORPHOQUANT' and the applied computer program. (5) The analysis of one cell soma with the 'MORPHOQUANT' amounts to about 30 seconds. (6) The computer accepted 30 to 50% of the offered objects. The remaining ones could not be discriminated from the neighbourhood. (7) 14 standard features are registered and 7 statistically evaluated preferential taking into consideration area, form and texture of the objects. (8) 4 features are statistically relevant: soma area in picture points (KOFL) and whole extinction (EXTS) correspond to soma size; compactness (KOMP) and concentration of high grey values in the central part of the object (ZNTR) correspond to structural features of the soma, i.e. the structural density and the distribution patterns of strong coloured RNA and DNA particles. Form factors are not statistically relevant. (9) With increasing age the morphological features are clearer and the performance of the classificator is higher. (10) Soma size and structure of pyramidal and stellate cells develop similarly to an overshooting growth curve. The values reach the maximum approximately on postnatal day 16. (11) Age-related methodological and neurobiological problems are discussed.