1. 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

7. AFRICAN/AMERICANASIANCAUCASIAN

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

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

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

18. INACTIVE TYROSINASE DUE TO MUTATION

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

20. 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.

21. 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.

22. 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.

28. MELANSOMES ARE TAKEN UP BY PHAGOCYTOSIS INTO THE LOWER KERATINOCYTES

29. “MELANOSOME COMPLEX” IN KERATINOCYTE

33. MELANOCYTES BEING PHAGOCYTOSED BY A KERATINOCYTE

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

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

38. Keratinocyte Growth Factor Promotes Melanosome Transfer to Keratinocytes

39. CULTURED MELANOCYTES (M) AND KERATINOCYTES (K)

40. MELANOSMES ARE GREEN (ANTI-TYROSINASE IMMUNOFLUORESCENCE LABELLING)

41. KERATINOCYTES ARE RED (ANTI-KERATIN IMMUNOFLUORESCENCE LABELLING)

42. CULTURED CELLS TREATED WITH KERATINOCYTE GROWTH FACTOR (KGF)

43. CULTURED CELLS EXPOSED TO UVB LIGHT

44. CULTURE TREATED WITH MELANOCYTE-STIMULATING HORMONE (MSH)

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