Morphological and histochemical observations of hepatic peroxisomes and lysosomes of rats after treatment with methylmercuric chloride, hydrogen peroxide and gamma radiation




Chowdhury, Anisuzzaman

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The ultrastructure of cytochemically identified hepatic peroxisomes and lysosomes was studied at days 2, 7 and 21 following treatment with hydrogen peroxide (HP), methylmercuric chloride (MMC) and gamma radiation (I). The HP group received five daily intraperitoneal (IP) injections of 1.8 ml of 1.5% HP; the MMC group received a single IP injection of 6 mg MMC per kg body weight; the I group received 750 R whole body irradiation. Morphometric parameters were quantitated by stereological methods. The volume, surface and numerical densities on unbiased representative micrographs were estimated by point counting.

The mean volume densities of hepatic peroxisomes of HP, MMC and I rats fell in the range of 0.94 (+OR-) 0.13 to 1.31 (+OR-) 0.14% of hepatocyte cytoplasm; surface densities ranged from 0.104 (+OR-) 0.013 to 0.127 (+OR-) 0.016 (mu)m('2)/(mu)m('3); numerical densities were in the range of 0.106 (+OR-) 0.013 to 0.128 (+OR-) 0.003 (mu)m('-3). The estimated mean volume densities of hepatic lysosomes of HP, MMC and I rats ranged from 0.45 (+OR-) 0.03 to 0.74 (+OR-) 0.04% of hepatocyte cytoplasm; mean surface densities ranged from 0.052 (+OR-) 0.002 to 0.077 (+OR-) 0.004 (mu)m('2)/(mu)m('3); mean numerical densities were in the range of 0.052 (+OR-) 0.004 to 0.070 (+OR-) 0.033 (mu)m('-3). None of the parameters showed any significant difference (P (LESSTHEQ) 0.05) between treated and control animals.

Morphological observations revealed severe cytoplasmic degradation at day 2 after HP treatment which persisted to a moderate extent at day 7; no signs of toxic effect were observed at day 21. Livers of MMC treated rats demonstrated disruption of peroxisomal, lysosomal and mitochondrial membranes and formation of different shapes and sizes of peroxisomes at day 2. Damage appeared to be mild at day 7 and no apparent damage persisted until day 21. Following the whole body irradiation of 750 R, granularity in hepatic peroxisomes, accumulation of rough endoplasmic reticulum, loss of mitochondrial cristae and presence of polyribosomes and/or glycogen were observed at day 2. Seepage of hydrolytic enzymes from disrupted lysosomal membrane and persistence of polyribosomes or glycogen and dissolution of mitochondrial cristae were observed at day 7. Diffusion of reaction products from peroxisomes and apparent dissolution and peripheral movement of crystalline cores was observed at day 21 after irradiation.



Hepatic Peroxisomes, Lysosomes, Rats, Morphological Characteristics, Methylmercuric Chloride, Hydrogen Peroxide, Gamma Radiation