The hepatocyte. Development, differentiation, and ageing.

1. Being the main organ of the metabolic system, the liver, whose function undergoes numerous changes in the course of life, is an important object of investigation. For this reason research into the structure and the associated functions of the hepatocyte, which plays a central role in the liver, is of special significance. 2. The study was carried out on male rats from birth up to the 27th month of life. Data obtained through similar experiments on female rats are available. The weight of the liver increases from 0.274 g at birth to 23.2 g at the end of the 27th month of life. The relative liver weight in relation to 100 g body weight diminishes from 7.7-5.3% in the prenatal phase to 4.5-2.6% in the first days of life, and increases again to 5.5% in the 1st and 2nd months of life. This is followed by a repeated drop in the relative liver weight to as low as 3.2 per cent. 3. The volume of the extrahepatocellular space diminishes during foetal development. Haematopoietic cells decrease from 63% of the liver volume on the 15th day to 37% on the 18th day of gestation. Kupffer cells account for less than 3% of the total liver volume in foetal and adult rats. Their number in foetal livers accounts for 4% of the total number of cells and in adult livers for 37%. The relative increase by a factor of about 10 is accompanied by an increase in the total volume by 130 per cent. 4. The volume density of the extrahepatocellular space diminishes from 0.403 at birth to 0.134 after 6 months. Generally, the extrahepatocytic space remains unchanged from the 1st month onwards, accounting for 10-15% of the total volume. 5. The volume density of hepatocytes is 0.60 on the 15th foetal day, increasing to 0.85 till the 21st foetal day. After birth till the end of the period of investigation the volume density varies between 0.78 and 0.94. At birth the volume of hepatocytes is 5775.9 microns 3. It increases to 10,000 microns 3 up to the 2nd month. It diminishes again to 7388.8 microns 3 till the 24th and 27th months. 6. Initially, the volume of hepatocytes drops to below the volume at birth, followed by an increase of 99% compared with the value at birth till the 6th month. After that the volume diminishes again to 127.9% of the volume at birth.(ABSTRACT TRUNCATED AT 400 WORDS)