Ultrastructure of the liver after hypoxia in the postnatal period

Repeated phases of hypoxia (8 h daily for 2 to 5 days at pO2 11.33 kPa = 5.000 m in altitude) were induced to Sprague-Dawley rats in the postnatal period as well as up to the 64th day of age, and after different recovery phases the ultrastructure of hepatocytes was qualitatively and quantitatively analysed. Major results were as follows: 1. Increases in body and liver weights were delayed but were balanced off after 64 days. 2. Qualitative alterations are reversible spherical transformations of mitochondria, a degradation of lipids and a slight increase in autophagocytosis. 3. The quantitative mitochondrial parameters (volume density, number per unit area, average volume) were not even adjusted to control values after 64 days. Granular endoplasmic reticulum and ribosomes/polysomes were insignificantly reduced in comparison to control animals, structure and arrangement are regular. Lipids and glycogen were differently altered. 4. The findings of the hepatocytes after postnatal hypoxia were reversible, though the majority of parameters had not yet returned to normal after 2 months. An adaptation to repetitive hypoxic conditions is not provable.