MELANOCYTES AND MELANOSOMES MELANOCYTES ARE THE CELLS THAT MAKE MELANOSOMES MELANOSOMES ARE MEMBRANE-BOUND ORGANELLES THAT SYNTHESIZE AND STORE MELANIN EUMELANIN IS BLACK MELANIN IS A COMPLEX POLYMER MADE FROM TYROSINE BUT OTHER MELANINS CAN BE YELLOW TO RED

AFRICAN/AMERICANASIANCAUCASIAN

AFRICAN/AMERICANASIAN CAUCASIAN 11% MELANOSOMES IN MEMBRANE- BOUND PACKETS 37% MELANOSOMES IN MEMBRANE- BOUND PACKETS 85% MELANOSOMES IN MEMBRANE- BOUND PACKETS

MELANOBLASTS MIGRATE FROM THE NEURAL CREST DURING EMBRYOGENESIS MELANOBLASTS DIVIDE TO FORM MELANOCYTES

LEUKODERMIA AN AUTO - IMMUNE DISEASE IN WHICH SOME MELANOCYTES ARE DESTROYED BY THE IMMUNE SYSTEM

INACTIVE TYROSINASE DUE TO MUTATION

MUTATION CAUSING SOME IMPROPER FOLDING THAT DOES NOT AFFECT TYROSINASE ACTIVITY. BUT GOLGI QUALITY CONTROL SENDS IT BACK TO THE RER.

INACTIVE TYROSINASE DUE TO MUTATION MUTATION CAUSING SOME IMPROPER FOLDING THAT DOES NOT AFFECT TYROSINASE ACTIVITY. BUT GOLGI QUALITY CONTROL SENDS IT BACK TO THE RER. CORRECT SUGARS ARE NOT ADDED TO OLIGOSACCHARIDES OF TYROSINASE. SO MISDIRECTED AT TRANS-GOLGI SYSTEM MAY BE PUT INTO SECRETORY VESICLES BY MISTAKE. LACK OF TYROSINE TRANSPORT SYSTEM IN MELANOSOME MEMBRANE.

INACTIVE TYROSINASE DUE TO MUTATION MUTATION CAUSING SOME IMPROPER FOLDING THAT DOES NOT AFFECT TYROSINASE ACTIVITY. BUT GOLGI QUALITY CONTROL SENDS IT BACK TO THE RER. CORRECT SUGARS ARE NOT ADDED TO OLIGOSACCHARIDES OF TYROSINASE. SO MISDIRECTED AT TRANS-GOLGI SYSTEM MAY BE PUT INTO SECRETORY VESICLES BY MISTAKE.

INACTIVE TYROSINASE DUE TO MUTATION MUTATION CAUSING SOME IMPROPER FOLDING THAT DOES NOT AFFECT TYROSINASE ACTIVITY. BUT GOLGI QUALITY CONTROL SENDS IT BACK TO THE RER. CORRECT SUGARS ARE NOT ADDED TO OLIGOSACCHARIDES OF TYROSINASE. SO MISDIRECTED AT TRANS-GOLGI SYSTEM MAY BE PUT INTO SECRETORY VESICLES BY MISTAKE. LACK OF TRANSFER TO KERATINOCYTES LACK OF TYROSINE TRANSPORT SYTEM IN MELANOSOME MEMBRANE.

MELANSOMES ARE TAKEN UP BY PHAGOCYTOSIS INTO THE LOWER KERATINOCYTES

“MELANOSOME COMPLEX” IN KERATINOCYTE

MELANOCYTES BEING PHAGOCYTOSED BY A KERATINOCYTE

PHAGOCYTOSED MELANOSOMES ARE DISTRIBUTED AS A CAP AT TOP OF THE NUCLEUS

LATEX BEADS TAKEN UP BY KERATINOCYTE AND FORMING A CAP ON TOP OF THE NUCLEUS

Keratinocyte Growth Factor Promotes Melanosome Transfer to Keratinocytes

CULTURED MELANOCYTES (M) AND KERATINOCYTES (K)

MELANOSMES ARE GREEN (ANTI-TYROSINASE IMMUNOFLUORESCENCE LABELLING)

KERATINOCYTES ARE RED (ANTI-KERATIN IMMUNOFLUORESCENCE LABELLING)

CULTURED CELLS TREATED WITH KERATINOCYTE GROWTH FACTOR (KGF)

CULTURED CELLS EXPOSED TO UVB LIGHT

CULTURE TREATED WITH MELANOCYTE-STIMULATING HORMONE (MSH)

BEGINNING OF A MALIGNANT MELANOMA (DUE TO UNCONTROLLED GROWTH OF MELANOCYTES) LOW POWER HIGH POWER