HISTOCHEMICAL OBSERVATIONS ON THE HARDERIAN GLAND OF THE ALBINO MOUSE

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Abstract
The Harderian gland is a compound tubulo-alveolar organ, apocrine in nature. In addition to its lipoidal secretion it usually contains a characteristic reddish-brown, porphyrin pigment. The glandular cells and alveolar lumina contain phospholipids, triglycerides, and possibly cholesterol or cholesterol esters. Alkaline phosphatase activity is present in the vicinity of the basement membrane and basal portion of the glandular cells. The cytoplasm and nuclei of the cells are weakly basophilic. No demonstrable glycogen, acid mucopolysaccharides or iron are present. The pigment is moderately to intensely sudanophilic and acid-haematein positive, is bleached by pyridine and mineral acids, contains no iron, is not dissolved by lipid solvents and is negative to the biuret test, xanthoproteic reaction, Millon reaction and the ninhydrin-Schiff reaction. It darkens with osmic acid and iron hematoxylin, reduces potassium ferricyanide, synthesizes indophenol and fluoresces with a bright red fluorescence. The presence of a saliva-resistant, PAS-reactive material or a peracetic acid-Schiff reactive material within the glandular lumina may have resulted from the oxidation of unsaturated fats. It is concluded that part of the lipid which the gland elaborates may be actually transformed into pigment or may be attached to the pigment as a lipoprotein complex. Evidence obtained is interpreted as supporting the concept that the gland, instead of being a passive storage organ for pigment formed elsewhere in the body, is actively engaged in the production of this pigment.