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General Pathology

Explore the classification, production, and functions of autogenous pigments such as melanin, ceroid, and lipofuscin. Learn about disorders affecting melanin pigmentation and associated metabolic disorders.

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General Pathology

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  1. General Pathology Basic Principles of Cellular and Organ Pathology Autogenous Pigments Jaroslava Dušková Inst. Pathol. ,1st Med. Faculty, Charles Univ. Prague

  2. Pigments Definition: colored substances in the organism or environment

  3. Pigments Classification: • endogenous • autogenous • hemoproteins derived • exogenous

  4. Autogenous Pigments -color substances formed in the organism as metabolism products • melanin • ceroid • lipofuscin

  5. Melanin • oculocutaneous (origin from tyrosine in melanocytes) • neuromelanin - subst. nigra (origin from dopamin)

  6. Melanin - types • eumelanin – insoluble , brown-black • phaeomelanin – soluble, yellow-red (high sulphur content)

  7. Melanin - production Melanocytes • derived from the neural crest • present in the basal layer of epidermis, dermis, hair folicles, mucose membranes, uveal tract of the eye, meninges, inner ear • secretory in the contact with the epithelial cells - cytocrinia

  8. Melanin Functions – 1. • cytoprotective • light absorption & conversion of the photon energy into heat • uvea – absorption of the light retina protection of light overexposure • retina - visual acuity preventing light reflexion from the fundus

  9. Melanin Functions -2. • Ion exchanging capacity Melanosomes can also act as detoxyfiing and excretory components accumulating great number of drugs and toxic component e.g. heavy metals. Scavengers of the free radicals. Rarely cytotoxic – photosensibilisation

  10. Melanin - Features • brown • destained with H2O2 • reducing AgNO3

  11. Lack generalized total albinism parcial albinism local vitiligo leucoderma Disorders of Melanin Pigmentation

  12. Albinism • autosomal recessive heredity • tyrosinase deficiency • tyrosinase positive – melanosomes defect • oculo-cutaneous albinoidism – dominant inheritance

  13. Lack generalized total albinism parcial albinism local vitiligo leucoderma Disorders of Melanin Pigmentation

  14. Vitiligo • familial aggregation • polygenic nature • association with other autoimmune diseases (DM, thyroiditis, gastritis) • ab against tyrosinase in the serum • autoreact . T- cellular cytotoxicity

  15. Lack generalized total albinism parcial albinism local vitiligo leucoderma Disorders of Melanin Pigmentation

  16. Leucoderma • postinflammatory circumscribed depigmentation e.g. • leucoderma syphyliticum • leucoderma psoriaticum

  17. Increase generalized Adison disease local freckles, nevi chloasma /melasma melanodermia melanoma Disorders of Melanin Pigmentation

  18. Increase generalized Adison disease local freckles, nevi chloasma melanodermia melanoma Disorders of Melanin Pigmentation

  19. Disorders of Phenylalanine and Tyrosine Metabolism 1. Phenylalanine hydroxylase PHENYLKETONURIA 2. Homogentisic acid oxydase ALKAPTONURIA 3. Tyrosinase ALBINISM

  20. Disorders of Phenylalanine and Tyrosine Metabolism Phenylalanine Tyrosine 1 3 Homogentisic acid DOPA 2 cc methyl– acetoacetic acid Norepinephrine Epinephrine MELANIN

  21. Ceroid • features • light brown • PAS + • acidoresistent • Sudan +- • origin • fagocytosis od lipid substances by macrophages • oxidation of non–saturated lipid acids

  22. Ceroid • localisation • places of erythrocytes destruction • necroses of adipous tissue • avitamonosis E • melanosis coli • Dubin - Johnson syndrome

  23. Lipochrom • ubiquitous pigment • exogenous origin • lipid solvent • histologically unprovable

  24. Lipofuscin • features • dark brown • Sudan +- • autofluorescence

  25. Lipofuscin • origin • autophagocytosis "wear and tear" pigment from the accumulation of autophagolysosomes over time.

  26. Lipofuscin • localisation • CNS, epithels, muscles, liver ATROPHIA FUSCA

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