With appearance of intensive chemotherapy regimens, methotrexate is a folic acid antagonist that is commonly used for the treatment of malignancies and rheumatic disorders.

To reflect the effects of methotrexate on growing lumbar vertebrae of young male albino rat and potential protective effects of folic acid.

30 young male Albino rats were equally divided into three groups. Control group (I), methotrexate treated group (II) was subcutaneously injected once daily at 0.75 mg/kg for two separate 5-days courses and methotrexate plus folic acid group (III) was given methotrexate as group II plus folic acid at a dose of 1mg/kg. The lumbar vertebrae were extracted and processed for the light and electron microscopic examination. Morphometric measurements were also done.

Normal histological structures were determined in the control group whereas methotrexate treated group revealed cellular disorganization with degeneration. The proliferative zone showed decrease in chondrocyte number with failure of the secondary ossification center to appear and the centrum showed abundant fat cells and few bone marrow cells. Both reserve and proliferating cells revealed rarified vacuolated cytoplasm. The morphometric studies revealed a significant decrease in both proliferative cell count and midzonal thickness of growth plate. On the other hand, rats received folic acid with methotrexate revealed more or less apparent normal architecture.

Folic acid proved to have remarkable protective effect against harmful effects of methotrexate. So, its supplementary should be started with …