Mechanism of Depigmentation by Hydroquinone

Histochemical (dopa reaction) and electron microscopic studies were carried out to elucidate the nature of the chemical depigmentation produced by hydroquinone (HQ). Depigmentation was induced by topical application or subcutaneous injection of HQ in black guinea pigs. The present study showed that HQ preferentially affected the nonfollicular and follicular melanocyte system. It caused decreased formation of melanosomes, a marked alteration in the internal structure of melanosomes, an increased degradation of melanosomes , and , finally, a destruction of the membranous organelles in the melanocytes. These findings indicate that HQ affects not only the formation, melanization, and degradation of melanosomes, but that it affects also the membraneous structures of melanocytes and eventually causes necrosis of whole melanocytes