ABSTRACT
Gibberellic acid is one of the plant growth promoting hormones that is used in agriculture to increase the growth of fruits and vegetables. The toxic effect of chronic oral exposure to this growth promoter on the histological structure of liver cells of rats was investigated into three groups, each was 12 rats. The first group received a daily oral dose of 70 mg/kg of gibberellic acid dissolved in distilled water for one month then animals were sacrificed. The second group received the same dose of gibberellic acid for one month then animals were left to recover and were sacrificed after two months from the last dose. The third group of animals served as controls and received a daily oral dose of distilled water. Liver specimens were taken from animals of each group, prepared for and examined by light and electron microscopes. The significant histological changes in the liver cells after exposure to gibberellic acid were presented in the form of swelling of the majority of cells, depletion of glycogen, appearance of large amounts of smooth endoplasmic reticulum, appearance of large areas of rarified cytoplasm separating dense areas of cellular organelles, increased of lysosomes, swelling and degeneration of many cells. Following substance withdrawal, a few cells became nearly similar to those of the controls, while the majority of cells remained affected. These data supported the deleterious effects of gibberellic acid on the liver after chronic oral exposure and the recovery from these effects might need a longer time. So, the need for protection from the hazards of these substances should be searched for and continued