List of abbreviations		 Vocabulary
of micros-
copic
anatomy
specialist terms
explained in
English +
German

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Editor:
Dr. med.
H. Jastrow
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Overview Peroxisomes = Microbodies (Peroxysoma):
Pages with explanations are linked to the text below the images when available
Detail of a
peroxisome (Type 3)		 this and other liver
microbodies		 overview thereof
(liver, monkey)		 Peroxisome type 3
(liver, rat) 1		 monkey liver cell: per-
oxisomes type 3 + 4		 renal tubulus cell +
peroxisome (monkey)
Peroxisome Type 3
(Liver, rat) 2		 Peroxisome Type 3
(Liver, rat) 3		 Peroxisome Type 3
(Liver, rat) 4		 Some type 3 peroxi-
somes (Liver, rat) 5		 Peroxisome Type 3
(Liver, rat) 6
Peroxisomes or Microbodies (Terminologia histologica: Peroxysomum, Peroxysoma) are spheroid organelles surrounded by a double (elementary) membrane. They contain a slightly electron dense matrix with fine granules. In some cases cristalloid structures (Terminologia histologica: Inclusio crystalloidea), the nucleoids with higher electron density appear in microbodies. Theses cristalliods consist of cristallin Katalase or Uratoxidase or uric acid oxidase. Peroxisomes have diameter of 200 - 500 nm. In principle, they are seen in all cells with nuclei; however greater amounts of peroxisomes are only encountered in cells of the liver and the kidney. On an average human liver cells (hepatocytes) show ~1,000 peroxisomes with a mean volume of 0.125 µm³ each. Cells with a higher content of microbodies are those that synthetise, metabolise or store lipids and/or steroid hormones: cells of the suprarenal gland cortex, Leydig-cells, corpus-luteum-cells, fat cells, epithelial cells of the gut. There are 4 different classes of peroxisomes:
Type 1 without nucleoid (human),
Type 2 non-cristalloid-core (hamster),
Type 3 cristalloid core (rat),
Type 4 peroxisomes with a marginal density or plate.
Half-life of peroxisomes is only 5 days. They are degraded by themselves or when fusing with lysosomes. The degradation takes just ~4 minutes.
Peroxisomes serve for synthesis or decomposition of hydrogen peroxide (H2O2), which is cytotoxic. Hydrogen peroxide is reacted to water and oxygen by the katalase. In general, peroxisomes mainly contain enzymes for oxidation. Their key enzymes are katalase and peroxidase; further they have D-aminoacidoxidase, uratoxidase, superoxid-dismutase and urikase (only in animals that, in contrast to humans, are capable of degrading ureic acid). The following metabolic processes are located in perxoisomes: synthesis of cholic acid, degradation of purines and amino acids, and the first steps of fatty acid degradation.
Microperoxisomes are smaller forms with diameters of 150-250 nm, that show a high content of catalase (40 %). Due to their own peroxidase microbodies have a positive reaction with diaminobenzidine. Peroxisomes are syntetised  by the rough endoplasmic reticulum, enlarge and ripe later in the cytoplasm by continious uptake of enzymes and proteins.

--> cytoplasm, rough endoplasmic reticulum, kidney, liver
--> Electron microscopic atlas: Overview
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Some pictures were kindly provided by Prof. Dr. H. Wartenberg; other images, page & copyright H. Jastrow.