Ultrastructure of Hepatocytes from Laboratory Mice Fed a Standard Dry Laboratory Animal Diet.

The significant destructive changes in ultrastructure of hepatocytes from laboratory mice kept in different vivariums in Moscow and fed with dry laboratory animal diets acquired from different domestic manufacturers that were not standardized for initial products were demonstrated using electron microscopy. Furthermore, disruption in the ultrastructure of liver parenchymal cells occurred regardless of the animal status (SPF or conventional), conditions of various vivariums, as well as the feed manufacturer. At the same time, studies on ultrastructure of liver hepatocytes from mice kept in the Charles River Laboratory facilities in Germany and fed with the Altromin Spezialfutter laboratory animal diet (GmbH & Co., Germany) that was produced using quality control of ingredients did not reveal destructive changes in the internal ultrastructure of hepatocytes. However, if these mice were later fed with the food produced in local manufactures, changes in the structure of liver cells developed after 2 months. Thus, feeding with dry diet from the domestic producers of an unspecified composition causes significant changes in the ultrastructure of hepatocytes in control animals, reflecting the development of some pathological processes in the body.

Mitochondria in Obliquely Striated Muscles of the Horsehair Worm Gordionus alpestris (Nematomorpha, Gordioidea) with Structural Organization Typical of Cells with Energy-Intensive Processes.

The ultrastructure of mitochondria in the flattened circomyarian fibers of the horsehair worm Gordionus alpestris (Nemathelminthes) was examined. In contrast to the previously published data, we showed these mitochondria to be giant elongated organelles that densely fill the central cytoplasmic space of the ribbon-like muscle fibers. No fundamental differences were found in the ultrastructure of the muscle tissue mitochondria in actively moving free-living and parasitic G. alpestris worms. The functional significance of the observed ultrastructural organization of mitochondria is discussed in connection with the necessity for an extended mitochondrial membrane system for a uniform supply of active muscle tissue with energy.

Study of Age-Dependent Structural and Functional Changes of Mitochondria in Skeletal Muscles and Heart of Naked Mole Rats (Heterocephalus glaber).

Morphometric analysis of mitochondria in skeletal muscles and heart of 6- and 60-month-old naked mole rats (Heterocephalus glaber) revealed a significant age-dependent increase in the total area of mitochondrial cross-sections in studied muscle fibers. For 6- and 60-month-old animals, these values were 4.8 ± 0.4 and 12.7 ± 1.8%, respectively. This effect is mainly based on an increase in the number of mitochondria. In 6-month-old naked mole rats, there were 0.23 ± 0.02 mitochondrial cross-sections per µm2 of muscle fiber, while in 60-month-old animals this value was 0.47 ± 0.03. The average area of a single mitochondrial cross-section also increased with age in skeletal muscles - from 0.21 ± 0.01 to 0.29 ± 0.03 µm2. Thus, naked mole rats show a drastic enlargement of the mitochondrial apparatus in skeletal muscles with age due to an increase in the number of mitochondria and their size. They possess a neotenic type of chondriome accompanied by specific features of mitochondrial functioning in the state of oxidative phosphorylation and a significant decrease in the level of matrix adenine nucleotides.

Morphometric Examination of Mitochondrial Ultrastructure in Aging Cardiomyocytes.

Mitochondrial ultrastructure in cardiomyocytes from 3- and 24-month-old Wistar and OXYS rats was investigated using a new approach designed for morphometric analysis. The data fully confirm the electron microscopy data: the area of the inner mitochondrial membrane per unit volume of mitochondria was significantly decreased with age, as found on heart muscle section. In 3-month-old Wistar rats from the control group, this parameter was 41.3 ± 1.52 µm(2)/µm(3), whereas in OXYS rats it was decreased to 30.57 ± 1.74 µm(2)/µm(3). With age, an area of the inner mitochondrial membrane per unit volume of mitochondria declined in both rat strains: Wistar - from 41.3 ± 1.52 to 21.47 ± 1.22 µm(2)/µm(3), OXYS - from 30.57 ± 1.74 to 16.3 ± 0.89 µm(2)/µm(3). A new method that we designed and used for morphometric analysis notably simplifies the process of morphometric measurements and opens up good opportunities for its further optimization using image recognition technology.