[Methodological problems and results of the volume and surface determination of rat liver cells during postnatal...

During the postnatal development of the liver cells until the 6th month of life, their volume increases to 199% of birth value, whereas the nuclear volume increases to 133%. From the 2nd month onwards, values are reached which correspond essentially to those of adult livers. In order to determine the surface it does not suffice to assume a spheroid to get real values. In addition, the number and size of the microvilli in the areas of the sinusoidal cellular surface and that one near the biliary canaliculi have to be determined. Taking into consideration the assessment of the microvilli the cellular surface increases at birth to 116.4% and in the 6th month to 124.3% of the smooth surface. These morphological findings - development of microvilli on the sinusoidal zone of the plasma membrane (6th month: 2,170) and the one near the biliary canaliculi (6th month: 340.2) - are closely connected with the functional behaviour of those plasma membrane areas.