RESUMO
The injectable contraceptive medroxyprogesterone acetate [MPA] is an internationally established option of birth control. To evaluate the possible effects of MPA on the structure of zona fasciculata cells, the adrenals of forty adult female albino rats were used. The experimental animals were divided into four groups treated as follows: group I was kept as control, groups II and III were injected intramusculary with MPA for 2 and 4 months respectively. Animals of group IV were injected for 4 months and sacrificed one month after the last injection. Specimens from the adrenal gland were taken and processed for light and electron microscopic examination. It has been found that MPA caused an increase in the thickness of zona fasciculate and activation of the cells when administered for 2 months. The cells showed numerous lipid droplets, large number of mitochondria and prominent smooth endoplasmic reticulum. However, MPA administration for 4 months resulted in reduction in the thickness of zona fasciculata with degenerative changes in its cells. The cells appeared small and separated from each other and exhibited many lysosomes and intracellular vacuolar spaces. After withdrawal, most of the cells appeared more or less normal and few cells showed some structural changes. These findings indicated that MPA at first caused activation of fasciculata cells and increased steroidogenesis, but prolonged use of MPA induced inactivation and degenerative changes in these cells. However some of these changes were reversible on withdrawal of the drug. Therefore precaution and follow up must be considered with prescribing this drug for prolonged periods