Table 2.

Characteristics of the developmental stages of melanosomes during melanin synthesis. The melanogenesis takes place in special organelles named melanosomes. As first develops a vesicle (Stage I) which builds inside a fibrillar matrix formed by glycoproteins (Pmel17, MART-1) and gets tyrosinase and other enzymes of melanogenesis (Stage II). The melanosome produces melanin, which polymerizes and settles on the internal fibrils (Stage III). In the last stage (Stage IV) melanosome is filled up with melanin

Melanosom features	Stage I	Stage II	Stage III	Stage IV
Shape	Spherical	Elongated	Elliptical, ellipsoidal	Elliptical, ellipsoidal
Internal structure	–	Matrix fibrils are visible	Matrix fibrils are visible	Matrix fibrils are covered by polymerized melanin
TYR	–	+	+	+
TYRP1	–	+	+	+
TYRP2	–	+	+	+
Melanin synthesis	–	–	Begins, settle on internal fibrils	Filled by melanin
Color			Brown	Dark brown to black