Structural changes in the rat's kidneys in case of tumor development and after intravenous injection of the short-lived radioactive isotopes

At present time the problem of interaction between tumor and organism attracts considerable attention of the researches. Without deep understanding of the complicated mechanism of interrelation between cancerogenic agents and organism, and then between organism and malignant cells it is impossible to understand correctly the reasons and conditions of tumor development, and to work out effective methods of the oncologic disease control.

Actuality. At present time the problem of interaction between tumor and organism attracts considerable attention of the researches. Without deep understanding of the complicated mechanism of interrelation between cancerogenic agents and organism, and then between organism and malignant cells it is impossible to understand correctly the reasons and conditions of tumor development, and to work out effective methods of the oncologic disease control. The tumor, from the beginning of its development, is a part of the organism and is connected with it [9].

Information that one can find in the available scientific literature was obtained in the process of clinical research, and it is concerned mainly with functional changes in kidneys in case of development of differently located tumors [1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19].

Taking into consideration the above mentioned we tried to study structural changes in the rat's kidneys in case of development of different experimental and spontaneous tumors, and after intravenous injection of short-lived radioactive isotopes.

Methods. The investigated kidneys were obtained from adult laboratory rats. There were six groups of the rats. The group №1 (control) included five intact animals. The group №2 included five animals that were subcutaneously injected with the strain of tumor cells of the experimental lymphosarcoma. The group № 3 included five animals that were intraperitoneally injected with the strain of tumor cells of the experimental ovarian tumor. The group №4 included five animals that were intraperitoneally injected with the strain of tumor cells of experimental sarcoma. The group № 5 included three animals that had spontaneous mammary tumors. The group №6 included seven animals with advanced spontaneous mammary tumors, the rats of this group were intravenously injected with short-lived radioactive isotope (18F).

Rats with experimental tumors were killed after full neoplasm development. Animals of the groups №1 and №3 were killed on the twelfth day after the beginning of the experiment. Rats of the groups №2 and №4 were killed on the twentieth day. Animals of the group №5 were killed after their spontaneous tumors were determined. Rats of the group №6 were killed on the seventh day after injection of the isotopes. After death of the investigated rats the abdominal cavity was opened and the kidneys were extracted and fixed in formalin solution. Paraffin sections were stained with hematoxylin-eosin. Histologic specimens were examined under a light microscope.

Discussion. Kidneys of intact control rats (group №1) is covered by a thin capsule that is 4,52±0,2 micrometers in thickness. The capsule is made up of numerous cellular elements containing densely stained oval and elongated nuclei and of thin connective tissue fibres. All the structural components of the capsule are arranged in compact way, they lie parallel to the surface of the organ.

In the renal parenchyma one can determine two distinct layers: cortex and medulla. The glomerules are scattered within the renal cortex, their average diameter makes up 76,2±2,9 micrometers. The glomerules are composed of tortuous capillaries that have distinguishable lumens. Parietal layer of the glomerular capsule is lined by squamous epithelium containing elongated nuclei.

The bulk of the renal cortex is made up of convoluted tubules that are lined by simple epithelium 7,6±0,19 micrometers in height. Cytoplasm of the epithelial cells is granular; cell boundaries and basal membrane are not prominent. Rounded and oval nuclei of the epithelial cells are characterized by conspicuous karyolemma and chromatin. The nuclei are 4,95±0,16 micrometers in diameter. The convoluted tubules contain lumen the average width of which is 18,17±0,8 micrometers. Between the convoluted tubules there are thinwalled blood vessels containing formed elements of blood.

The renal medulla is made up of medullary rays (straight tubules) that are lined by squamous epithelium 3,35±0,13 micrometers in height. The boundaries of the epithelial cells are not prominent, their cytoplasm is granular. Nuclei of the cells are oval in shape and they are oriented along the tubules. The nuclei have conspicuous karyolemma, nucleoli and chromatin. Average diameter of the nuclei is 4,17±0,12 micrometers. The medullary tubules contain lumen that is 13,34±0,5 micrometers in width.

In the kidneys of the rats of the group №2 one can find wrinkled renal glomerules. Average diameter of the glomerules is 64,57±2,17 micrometers. In many cases the epithelium of the cortical tubules is characterized by strongly pronounced signs of degeneration. In some zones the epithelium is preserved and it is 8,38±0,16 micrometers in height. The epithelium of the tubules is often devoid of nuclei. There are also layers of preserved epithelium that have lost their connection with basal membrane. In some of the epithelial cells the apical parts are destroyed, many of the cells are vacuolated.

In many of the tubules situated within peripheral cortical zones the epithelial lining is absent. There are also not numerous cavities that have formed in places of entirely destroyed renal tubules. Blood vessels of the cortex are engorged with blood.

In the renal medulla the degenerative changes are more feebly marked than in the cortex. But some of the medullary tubules are devoid of epithelium, and some of the tubules are lined by either anucleate epithelial cells or vacuolated cells. In some zones the epithelial cells have lost their connection with basal membrane. In some cases the lumen of the tubules is filled with fragments of epithelial cells among which well preserved nuclei are irregularly scattered.

Within the renal medulla there are some small cavities that are filled with homogeneous colloid-like vacuolated substance. Medullary blood vessels are hyperemic.

In the kidneys of the rats of group №3 the capsule is thickened (12,79±0,52 micrometers). It is made up of numerous cellular elements containing oval and elongated nuclei, and of thin connective tissue fibres that lie along the surface of the organ.

In some cases the renal glomerules are characterized by widened capillaries that are engorged with blood. In other cases the glomerules are wrinkled and the parietal layer of the glomerular capsule is destroyed.

In the epithelium of the convoluted tubules degenerative changes are determined to different degrees. There are epithelial cells that are devoid of nuclei. In some zones the epithelium represents anhistous mass that has lost connetion with basal membrane; within that mass some well preserved nuclei are irregularly scattered. In some cases the epithelium is so increased in size that it closes up the lumen of the tubule entirely. Thin connective tissue bundles between the convoluted tubules are visible more distinctly than in the kidney of the rats of control group.

In the renal medulla the degerative changes are more feebly marked than in the cortex. Lumen of straight tubules is increased in size, average width of the lumen is 16,61±0,78 micrometers. The epithelium is increased in height (5,93±0,27 micrometers). Nuclei of the epithelial cells are rounded and oval in shape and their diameter is larger than that in the rats of control group (5,46±0,15 micrometers). In some zones the epithelium of the straight tubules is cast-off.

Kidneys of the rats of the group №4 are characterized by extensive destructive changes. Entirely preserved renal glomerules are not found. Most of the glomerules represent wrinkled anhistous mass. There are also empty scleroid glomerules.

Not numerous preserved renal tubules are lined by epithelial cells the boundaries of which are not distinct. Nuclei of the epithelial cells are rounded and oval in shape, they have prominent karyolemma and nucleoli. Destruction of the renal tubules is accompanied by thickening of basal membrane and disappearance of the nuclei of epithelial cells. Lumen of the tubules was gradually closed up by the collapsing epithelial cells. There are numerous necrotic zones that represent anhistous masses within which nuclei are irregularly scattered.

In the kidneys of the rats of the group №5 many of renal glomerules are wrinkled or collapsed.

In the renal medulla the epithelium of tubules is often cast-off. One can often find zones of homogeneous anhistous vacuolated mass. There are also zones that are made up of destructive tubules, those zones are infiltrated by formed elements of blood. Kidneys of the rats of the group №6 are characterized by hyperemia. Renal glomerules are not so numerous than those in the kidneys of control rats. Within the most peripheral zones of the cortex the convoluted tubules are widened. In the deep parts of the cortex there are cavities that have formed in place of entirely destroyed renal tissue.

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