SKCIN Melanoma begins in melanocytes the cells that produce the pigment melanin that colours the skin, hair and eyes and tans the skin when it is exposed to UV radiation GASTROINTESTINAL HEMORRHAGE (2): Melena. Melena, the passage of black, tarry stools, usually implies blood loss greater than 500 ml originating anywhere between the oropharynx and the right hemicolon. Melena occurs most often, What is the Difference Between Melanocytes and Melanosomes Pediaa.Com Melanocyte differentiation and mechanosensation are differentially modulated by distinct extracellular matrix proteins EMBO Reports Springer Nature Link