Features of cells and extracellular matrix ratio in rat meniscus for motor activity formation during the first two weeks of postnatal life in norm and after intrafetal antigen injection.

Abstract

Background. Diseases of the musculoskeletal system and connective tissue are included in the most common among school-age children. Undifferentiated connective tissue dysplasia syndrome is the morphologic basis for their progress. Previous researches showed that intrafetal antigen injection can be used for its modeling. Reactivity of the knee joint meniscus is not studied in this condition. Objective. To establish the features of the dynamics of cells and extracellular matrix ratio in the menisci of rat knee joint in norm and after intrafetal antigen injection from the 1st to the 14th day of life. Methods. 80 white laboratory rats were studied. 30 rats were intact. 30 rats underwent transuterine, transmembranous, intrafetal injection of liquid purified staphylococcal anatoxin (10-14 binding units in 1 ml, tenfold diluted, 0.05 ml) on the 18th day of prenatal period according to the method of M.A. Voloshyn. 20 rats after injection of saline solution served as control. Paraffin sections of left knee joint were made and stained with alcian blue (pH 2,6, MgCl2 critical concentration 0,2 M). In the sections the relative area of cells and matrix in the inner and outer zones of medial and lateral meniscus were measured. Zones were divided according to their cells types: fibroblast-like cells in the outer zone and chondrocyte-like cells in the inner one. Results were considered significant at p < 0.05. The differences between the averages were evaluated using Student's t-test. Results. On the 1st day of experiment in both zones of the medial meniscus the relative area of cells increases as compared to the norm. During two weeks it decreases, except for the day 11th when it is significantly more in the outer zone. In the inner zone of the lateral meniscus cells relative area is less on the 11th day of the experiment, but more on the 1st and 14th. During the 1st week of postnatal life in the experiment the amount of extracellular matrix in the outer zone is significantly higher than in norm, and later, during the second week, it was not significantly different. Conclusion. It was established that the prenatal action of antigens leads to the disorder of the rate and terms of morphogenesis during the formation of motor activity, which is manifested by the changes in the ratio of cells and matrix as compared to the norm.