Ayannuga Olugbenga Ayodeji, Ejiwunmi Adedayo Babaiola.
The effect of intrauterine exposure to tetracycline on the population of hypertrophic chondrocytes in the growth plate of long bones in mice.
Pak J Pathol Jan ;17(4):161-4.

Introduction: The hypertrophic chondrocytes is one factor that determines the size of growth plates. Tetracycline, a broad-spectrum antibiotic is known to result in limb shortening following prenatal exposure in mice. The effects of 12mg/kg body weight of tetracycline on the size and number of hypertrophic chondrocytes of the growth plate of mice was investigated in the study. Study design: 10 adult pregnant mice were randomly divided into 2 groups of 5 mice each. One group was designated as the experimental group and had 12mg/kg body weight of tetracycline between days 11 and 15 of gestation. The other group known as the control group had normal saline during the same period. 49 foetal mice were harvested on the 20th day of gestation from the 2 groups. Statistical analysis was done using paired student T- test. Materials and methods: Oral tetracycline at 12mg/kg body weight was administered to pregnant mice between 11th and 15th day of gestation. The foetuses were harvested on the 20th day of gestation. The humeri of the foetuses were fixed in formal saline and histological slides were made using Toluidine blue as the stain. Measurements were made with the use of a micrometer. Results: No gross anomaly or significant growth retardation was revealed. However, a significant reduction of humeral length was observed (T-cal=7.359, P>0.05) with associated significant cell depletion, particularly in the distal growth plate. There is however, no significant difference in the cell population in the proximal growth plate and the cellular density of both proximal and distal plates. Conclusion: At the aforementioned dose, tetracycline does not appear to cause any significant growth retardation or foetal anomaly. However, it causes a cell-depleting effect particularly on the distal growth plate. This shows that the cell depleting effect of tetracycline is anatomical site dependent.

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