How do keratinocytes acquire melanin?
a. Keratinocytes acquire melanin precursors (e.g., tyrosine) from melanocytes via plasma membrane amino acid transporter proteins
b. Keratinocytes phagocytize cytoplasmic processes of melanocytes that contain melanosomes
c. mRNA molecules that code for melanin proteins are exported from melanocytes to keratinocytes
d. Melanocytes synthesize melanocyte-stimulating hormone., which binds to recep-tors on keratinocytes
e. Melanocytes undergo apoptosis and export melanosomes via a holocrine mode of secretion
ANS: B
Melanocyte processes, containing melanosomes, are phagocytized by keratinocytes of the skin.
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