[Seasonal changes in the testes of the silver fox].

In 14 mature male silver foxes in spring and autumn by means of counting dots and transsections, relative and absolute summational volumes and areas of the seminiferous tubule surfaces, interstitial glandulocytes (Leydig's cells) and stroma have been calculated. Average diameter and total length of the tubules have been determined. Increased mass of the testes in spring is the result of a proportional enlargement of the total volume of the seminiferous tubules and stroma, while the total volume of the endocrinic part in the organ changes insignificantly.

[Relative hypertrophy of the right ventricle in silver foxes selected for domestication behavior].

Silver foxes selected for domestication behavior were found to have relative hypertrophy of the right heart ventricle, which was 21% as enlarged in males and 18% as enlarged in females as compared with non-domesticated animals. It was established by stereological methods that hypertrophy occurs mainly at the expense of an increase in the absolute and relative content of myofibrils in cardiomyocytes, with the absolute total volume of the mitochondria being equal both in domesticated and non-domesticated animals. It was shown by means of dissociated cell counts that in both animal groups, the absolute number of cardiomyocytes and their nuclei in the right ventricles is approximately similar.

[Adrenaline-induced damage to the myocardium in rats with genetically determined arterial hypertension].

Genetically hypertensive and normotensive rats were subjected to acute myocardial injury by a single subcutaneous injection of adrenaline (0.5 mg/100 g bw). The animals were sacrificed one day later.

[Ratio of spontaneous and o-aminoazotoluene-induced hepatocarcinogenesis in mice].

No correlation was found between the frequency of spontaneous and o-aminoazotoluene (o-AAT)-induced hepatic tumours in mice. High susceptibility to tumour induction with o-AAT in mice both genetically susceptible (strains CBA and A/He) and resistant (strains DBA/2J and DD) to spontaneous hepatocarcinogenesis was detected. The CC57BR mice predisposed to spontaneous hepatomas were insensitive to their induction with o-AAT.

[The phenomenon of cardiomyocyte disappearance in plastic insufficiency of the myocardium].

The anthracycline cytostatic rubomycin hydrochloride was injected into male Wistar rats to induce plastic myocardial insufficiency. Light and electron microscopy and the method of alkaline dissociation of the myocardial tissue to obtain isolated cardiomyocytes were applied to examine the rat heart ventricles under the conditions of suppression of the DNA-dependent RNA synthesis and synthesis of specific proteins. Apart from the involutional processes occurring in the cardiomyocyte cytoplasm resulting in myocardial atrophy, the authors discovered a decrease in the number of muscle cells called "the disappearance phenomenon", since the mechanism of the elimination of a considerable number of cardiomyocytes could not be specified.

[Age-related changes in the cardiomyocyte population of the heart ventricles of white rats].

The total number of muscle cells and their nuclei in the rat ventricle walls at the age from 3 to 30 months was counted by means of alkaline dissociation of the prefixed myocardium. The total number of cardiomyocytes and their nuclei was shown to increase on the second year of life, this increase being much more pronounced and attaining the maximum much earlier in the right ventricle than in the left one. At the senile age (30 months) the number of cardiomyocytes in the ventricles decreases but the mean size of cells increases.

[Stereological analysis of myocardial structures in plastic heart insufficiency].

Electron microscopy, morphometry and stereological analysis were used to examine structural components of the myocardium of Wistar rats after injection of the anthracycline antibiotic rubomycin. Using the determination of absolute summary weights of cardiomyocytes, interstitial connective tissue, vessels and intercellular space as well as of the volume and surface densities of these structures the development of involutional atrophic lesions in the myocardium was demonstrated. The connective tissue showed an increase in the population of fibroblasts, diffuse activation of protein synthesis in them and collagen synthesis de novo.

[Ultrastructural changes in the cardiomyocytes in protein synthesis disorders].

Electron microscopic study of cardiomyocytes of Wistar rats using an experimental model of myocardial insufficiency induced by injection of rubomycin was carried out. A number of submicroscopic changes occurring in cardiomyocytes when protein synthesis was disturbed (autophagy and sequestration of glycogen, focal cytoplasmic degradation, increased number of secondary lysosomes) were shown to be the structural manifestations of inhibition of RNA synthesis in the nucleus. Alongside with involutional processes, the pathological changes of basic organelles consisting of thinning of myofibrils and decrease of mitochondrial membrane stability were revealed.

[Morphological types of the changes in the myofibrils of cardiac muscle cells].

Light microscopy and electron microscopy examinations showed the changes in myofibrils to be a criterion of early stages of cardiomyocyte involvement. Proceeding from this, the main types of acute cardiomyocyte damage are distinguished: contractures (segmentary and subsegmentary), primary clump degeneration, intracellular myocytolysis and cytolysis. The best way to detect the state of myofibrils by light microscopy is to use polarization microscopy which diagnoses in sections acute metabolic damages and early stages of myocardial infarction, repeated and relapsing infarctions, fibrillation of ventricles.

[Stereological study of the absolute total volumes of the structural components of the myocardium in hypertrophy].

Wistar rats weighing 200 g were exposed in a low pressure chamber to daily adaptation to altitude hypoxia 8 hours long at an "altitude" of 8000 m. On the 40th experimental day the weight of the left heart ventricle was 41.5% higher as compared to controls.

[Formation of transversely oriented myofibrils in myocardiocytes in the presence of heart enlargement].

Myocardial hypertrophy was induced in rats and mice by training in the pressure chamber (high altitude hypoxia) or ligation of the apex of the heart. Transversely oriented myofibrils developed in the subsarcolemma area of some cardiomyocytes of the ventricles in a fortnight; the Z bands of the newly-formed myofibrils were connected with the T tubules as in the normal myofibrils. It is supposed that this phenomenon was due to the appearance under the sarcolemma of transversely directed mechanical forrces as a result of enlargement of the cell volume.

[Morphologic reflection of protein biosynthesis disorders in the myocardial cells of rabbits with acute diphtheritic intoxication].

The lethal dose of diphtheria toxin (IDLM per 1 kg of body weight) was injected to Chinchilla line adult rabbits. Histological and electron-microscopy investigations were carried out in time periods from 3 to 24 hours following the administration of the toxin. Degenerative and necrotic changes in the myocardial cells under conditions of the given experiment were not observed.

[Cytologic changes in the myocardia of rats trained to altitude hypoxia].

Rats trained to the high-altitude hypoxia displayed signs of intensification of both the plastic and lytic processes; one of these processes prevailed in different cells. There was no significant change in the mitochondrial and myofibrillar ratio. An increase of the relative volume of the microcirculatory bed on account of dilatation of small vessels without any increase of their count was noted.

[Detection of damaged myocardial cells in histological sections by photochemical fluorochroming].

The effect of photochemical fluorochromizing used in the method suggested consists in the following: after the exposure of sections to short-wave ultraviolet irradiation the preparations start to fluorescence intensively in the visible region with the long-wave the myocardium of mice, dogs and section materials showed that following photochemical fluorochroming the intensity of lumenescence of damaged cells of the myocardium increased markedly as compared with that of intact cells. The authors recommend to use the described method in diagnosis of early stages of ischemic lesions of the myocardium.

[Early stages of myocardial infarct studied by opitcal methods].

The hearts of 45 dogs were investigated at times from 10 minutes to 24 hours following ligation of the anterior interventricular branch of the left coronary artery. The material was fixed in formalin and embedded in parafin. It was established that at early stages of experimental myocardial infarction in the zone of eschemia there took place eschemic zone various foms of contactural damages, lumpy decmposition, relaxation and sarcoplasmic matrix.

[Preparation of isolated cells by alkaline dissociation of formalin fixed tissue].

A procedure is described for preparation of isolated cells by treating formaldehyde fixed tissues with a 50%-solution of KOH. This results in complete yield of cells from a variety of organs (liver, kidney, heart, spleen, etc.).

[The effect of acetylsalicylic acid on the development of infarct-like myocardial necroses experimentally induced in rats by a single administration of novodrin (isopropylnoreadrenaline)].

It appeared that acetylsalicylic acid considerably decreased both development of the infarction-like foci of necrosis and primary damage of the myocardial cells experimentally induced in animals by direct action of novodrin and expressed in the course of the first hour. This led to the supposition that acetylsalicylic acid not only prevented platelet aggregation, but also increased the resistance of the myocardial cells to the injurious action of catecholamines.

[Focal myofibrillar disorganization in acute metabolic impairment of somatic musculature].

Skeletal muscles of rats and rabbits were studied by the target electron microscoptic and polarization-optic methods after administration of toxic substances and experimental acute ischemia of the extremities. Two types of foci of the myofibrillae disaggregation were described along with contracture injuries. The first occurred on the basis of relaxation and was expressed in total dysaggregation and lysis of myofibrillae; with the second type lysis occurred in the partially contracted fibers and began in the I-discs leading to diastasis of A-discs.