Brief introduction

1. THE MELANOCYTE &
MELANIN SYNTHESIS
Dr. Rahul pratap s
chouhan [Resident 1st
year} Dermatology
department

2. • DEFINITION OF MELANOCYTE:
Are neural crest-derived dendritic cells
•Mainly located in the stratum basale of
skin’s epidermis &
•Synthesize melanosomes.

3. FUNCTION OF MELANOCYTES:
Is to synthesize melanin in membrane-
bound organelles called melanosomes &
to transfer melanosomes to neighbouring
keratinocytes to provide protection from
UV irradiation.

4. TYPES OF MELANOCYTES
1- SECRETORY MELANOCYTES:
-Present in basal layer of epidermis form network
of dendrites in the basal layer
-They act as unicellular glands producing
melanosomes that are transferred to
surrounding epidermal keratinocytes (cytocrine
activity)

5. 2- NON-SECRETORY MELANOCYTES:
Called MELANOPHORES do not transfer
melanosome but redistribute them from
perinuclear zone into dendrites and back
again.

6. SITE SPECIFIC MELANOCYTES
A. Cutaneous melanocytes
B. Hair follicle melanocytes
C. Ocular melanocytes
D. Otic melanocytes

7. MELANOSOME
Is membrane bound unique organelle
Within the cytoplasm of melanocytes
in which in which melanin pigments
are synthesized, deposited and
transported.

8. SYNTHESIS & DISTRIBUTION OF
MELANIN IN THE
EPIDERMIS INVOLVES SEVERAL STEPS
1) Transcription of proteins required for
melanin synthesis
2) Melanosome biogenesis
3) Sorting of melanogenic proteins into
melanosomes to initiate melanin synthesis
within the melanosome

9. 4) Transport of the mature melanosomes to
the tips of melanocyte dendrites migrates via
microtubules.
5) Transfer of melanosomes to keratinocytes

10. MELANIN SYNTHESIS

11. FACTORS CAUSING MELANOCYTES TO
INCREASE MELANIN PRODUCTION
1) UV irradiation (direct effect)
2) Keratinocyte paracrine factors induced
by UV irradiation (indirect effect)

12. MELANIN TYPES
-Eumelanin ( brown & black)
-Pheomelanin
-Neuromelanin

13. 1. EUMELANIN( BROWN, BLACK)
-Black eumelanin in the absence of other pigments causes grey hair.
-Brown eumelanin in the absence of other pigments causes yellow
(blond) color hair.
-Insoluble in all solvents
-Nitrogenous pigment
-Oxidative polymerization of 5-6dihroxindole derived from tyrosine
-Manufactured in ellipsoidal melanosomes

14. 2. PHEOMELANIN (RED, YELLOW)
- Imparts a pink to red hue, depending upon its concentration.
- Concentrated in the lips, nipples, glans penis, and vagina.
-When small amount of brown eumelanin in hair mixed with red pheomelanin,
the result is red hair.
-Alkali soluble, contain Sulphur addition to nitrogen, Females>Males
-Oxidative polymerization of CYSTINE-S-YI-DOPA Via 1-4BENZOTHIAZINE
intermediates
-Manufactured in spherical melanosomes
-lips, nipples, glans of the penis, and vagina
-Is carcinogenic

15. THANK YOU