Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hair follicles and the eyes of pallid mice (C57/6J-Pa/Pa) and those of black mice (C57/6J-+/Pa) were examined ultrastructurally, histochemically, and biochemically to determine the cause of pigment dilution. The pigment cells in the hair follicles and the eyes of pallid mice have less mature melanosomes than those of black mice. In the hair follicles the pallid melanosomes were transferred into keratinocytes and became aggregated. In the eyes they were already aggregated within the pigment cells and were digested in acid phosphatase-positive lysosomes. The activity of acid phosphatase, a marker of lysosomal enzymes was significantly higher in pallid hair follicles and eyes than in black hair follicles and eyes. Dopa reactions at light and electron microscopical level indicated that the pigment cells in each tissue produced a large amount of Dopa oxidase when compared with those in each black counterpart. However, the rate of hydroxylation of L-tyrosine-3,5-3H was significantly lower in the pallid eyes than in black eyes, while this rate was significantly higher in pallid hair follicles than in black hair follicles. Immediate digestion of melanosomes within the pigment cells, i.e., autophagocytosis, seemed to explain the low activity in the pallid eyes. The diluted coat and eye colors of pallid mice are, therefore, not related to low Dopa oxidase activity but to immaturity of melanosomes and high activities of lysosomal enzymes; these enzymes seem to digest many of these immature melanosomes and contribute to the diluted coat and eye colors of pallid mice.
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PMID:Ultrastructural, histochemical, and biochemical studies of the melanin metabolism in eye and skin of pallid mice. 680 5

In an attempt to determine the factors involved in ocular pigment variation, the eyes of pallid mice (c57BL/6J-Pa/Pa), and those of littermate black mice (C57BL/6J-+/Pa) were examined ultrastructurally, histochemically, and biochemically. As controls, the eyes of black and congenic albino mice (C57BL/6J +/C2J and -C2J/C2J) were also examined. In the developing pallid mouse eye the retinal pigment epithelium (RPE) and choroid contained immature melanosomes with incomplete melanization. In the adult pallid RPE, numerous lysosomal structures containing melanin components were present, while in choroid, melanosome numbers not only increased but many were aggregated in large membrane-bound granules. These RPE and choroidal structures may be melanolysosomes because of their histochemical acid phosphatase positive reactions. Biochemically, the activity of acid phosphatase in ocular homogenates of pallid eyes was significantly higher than in either the black eyes of +/Pa or in the albino and black eyes of the C2J genotypes. Dopa reactions at the light and electron microscopic levels indicated that Dopa oxidase activity was present in the cells of the RPE and choroid of both pallid and black mice. Histochemically the Dopa reaction of pallid pigment cells seemed to be equal to that of black ones, suggesting that tyrosinase production might be normal in pallid pigment cells. Biochemically, however, tyrosinase activity in the pallid eye was significantly lower than in the black control. It is concluded that the active digestion of melanosomes, as well as the low ocular tyrosinase activity and the immaturity of pallid melanosomes, may contribute to the pigment dilution observed in the pallid mouse eye.
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PMID:Ultrastructural, histochemical and biochemical studies of the melanin metabolism in pallid mouse eye. 712 80