A comparative electron microscopic study of bone repair after internal fracture, osteotomy, and perforation of rat tibia.

BACKGROUND AND OBJECTIVE. Although previous studies have provided new information on bone repair, there are still gaps in knowledge about resorptive and formative processes during bone repair at the electron microscopic level. The aim of this study was to compare bone repair after the internal fracture, osteotomy, and bicortical perforation of the tibia by means of electron microscopy. MATERIAL AND METHODS. An electron microscopic study of bone repair after the internal fracture, osteotomy, and bicortical perforation of the tibia was performed on 72 male Wistar rats. Rats undergoing osteotomy and perforation were further subdivided into the control and immobilization subgroups. Bone repair was observed during the first posttraumatic weeks. RESULTS. Although bone repair in general had similar bone healing stages in all the groups, the repair process depended on the mode and degree of injury thus being different in the experimental groups. After the internal fracture, indirect ossification was observed; after osteotomy, primary periosteal, secondary endosteal ossification was noted; and after perforation, primary endosteal, secondary periosteal ossification was documented. Immobilization had an inhibitory effect on bone repair. CONCLUSIONS. The results of the present study gave new information at the electron microscopic level about intracellular changes and intercellular matrix synthesis during different types of posttraumatic bone repair and confirmed our previous reports on similar posttraumatic bone repair in histomorphometric and immunohistochemical studies.

Application of Photoshop-based image analysis and TUNEL for the distribution and quantification of dexamethasone-induced apoptotic cells in rat thymus.

UNLABELLED: The aim of the present study was to determine the target site cells in the rat thymus after exposure to the synthetic glucocorticoid, dexamethasone, at therapeutic doses. The findings of histology and histochemistry (Feulgen, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling--TUNEL) with quantification by computerized histomorphometry are described. MATERIAL AND METHODS: A quantified investigation of apoptotic and mitotic thymic lymphocytes in 36 young adult Wistar rats was performed at 1-7 days after a 3-day injection of dexamethasone (a total dose of 1.2 mg/rat intraperitoneally). RESULTS: At the first day after dexamethasone administration the moderate involution and atrophy of thymus histology were observed with simultaneous fall in cortical cellularity and mitotic activity of thymocytes. More rapid fall appeared in the inner cortex. The number of apoptotic (TUNEL-positive) cells was significantly increased. On the days 5 and 7 the expression of apoptosis and the cell proliferation were at almost normal level. CONCLUSIONS: The findings suggest that dexamethasone-induced apoptosis of cortical thymic lymphocytes, mainly correlated with synchronous inhibition of mitosis and cell number fall in thymus. The main target sites of dexamethasone injury were cells in the inner cortex of lobuli thymi.

Transport proteins in rats' renal corpuscle and tubules.

UNLABELLED: The localization of transepithelial transport proteins for glucose and water reabsorption in renal corpuscle and tubules epithelium was observed. MATERIAL AND METHODS: Immunohistochemistry of normal male Wistar rats' kidney has been performed. Facilitated diffusion glucose transporter GLUT4, Na(+)-dependent glucose co-transporter SGLT1, a cargo transporter TGN38, and water transporter aquaporin-2 (AQP2) were used. RESULTS: An intensive GLUT4 expression in renal proximal tubules and in convoluted segment of distal tubules has been observed. The intensive SGLT1 expression was marked in all renal tubules, and also in the glomerulus of the renal corpuscle. TGN38 was expressed mainly in the S1 of proximal tubules and a bit weaker in the distal tubules. The most intensive AQP2 expression in the proximal tubules and in the thin part of Henle's loop has been detected. In some cases AQP2 expression in the collecting tubules has been observed. The same tubules nephroni are marked heterogeneously. The distribution of transepithelial transport proteins in different parts of nephroni is also greatly heterogeneous because of weak determination of urinary system. CONCLUSION: The comparable transport-proteins distribution with technique of fluorescence immunohistochemistry in rats' renal corpuscle and tubules was elucidated. Data suggest that expression of glucose and water transepithelial transporter proteins is heterogeneous in all parts of nephron, and, probably, is in accordance with recycling of transport proteins.

Callus area and glycosaminoglycans content of the traumatized tibia in rats.

UNLABELLED: The aim of the present work is the quantification of the post-traumatic bone healing histology (total callus morphometry) and histochemistry of the glycosaminoglycans (GAG) content (microspectrometry) in rats tibia after segment osteotomy and bicortical perforation of trained and immobilized animals. MATERIAL AND METHODS: A quantified investigation of post-traumatic bone repair histology and GAG content after osteotomy and perforation of tibia in 105 young adult male Wistar rats has been performed. The repair was studied in normal and affected (training and immobilization) animals at 1-42 days after operation. RESULTS: The posttraumatic bone repair is an ordinary process of osteohisto- and organogenesis, and dependent on the environment factors (mode and degree of trauma, training of animals, etc.). The repair is trauma-dependent; after osteotomy the total callus area is significantly larger respectively to perforation. Otherwise, the training did not significantly influence the repair callus area and GAG content and therefore did not accelerate the bone repair, whereas the immobilization of animals depressed these processes and the bone repair was inhibited. CONCLUSIONS: Quantified study of histology and histochemistry of bone repair after perforation gave important new, more detailed results on the reparative histogenesis of the bone tissues: repair dynamics of callus areas, dynamics of GAG concentration, effects of mode and degree of trauma, training and immobilization on the repair process.