Quantitative Changes of the Endoplasmic Reticulum, Ribosomes and GERL in the Hepatocytes During Postnatal Development of Male Rats

Abstract

Summary Quantitative changes in endoplasmic reticulum, ribosomes/polysomes, Golgi apparatus, and in lysosomes were studied in male Wistar rats aged 0 (birth), 1, 2, 3, 4, 5, 6, 7, 14, 21, 28 days and 2, 3, 4, 5, and 6 months. The volume density of granular endoplasmic reticulum 1st 0.0470 at birth, it increases to 0.0545 by the 6th month (= 116%). At the same time the volume density of free ribosomes decrease from 0.0381 to 0.0166 (= 44%). Agranular endoplasmic reticulum increases from 0.0051 to 0.0186 (= 364%). But the total amount of all three components does not change substantially (0.0902 : 0.0897 = 99%). At birth, the ratio is 52.1 (granular endoplasmic reticulum) : 42.2 (ribosomes) : 5.7 (agranular endoplasmic reticulum), while at the end of the 6th month it is 60.8 : 18.5 : 20.7. During this period, Golgi apparatus diminishes from 0.017 to 0.008 (= 47%), the absolute volume per cell remaining almost constant (80.1 µm3 : 80.6 µm3). It can be shown in quantitative terms that Golgi apparatus is concentrated mainly in the zone adjoining the bile canaliculi (0.044, at birth : 0.053, in 6th month). The total number of lysosomes per hepatocyte increases from 31.4 at birth to 184.3 by the 6th month. At birth, 75.2% of the lysosomes are of the primary form, at the end of the 6th month their number decreases to 17.8%. The quantitative changes in endoplasmic reticulum, ribosomes, Golgi apparatus, and lysosomes are connected with growth and metabolic changes in the organism as a whole and in the liver.