Melanogenesis in amphibians. III. The buoyant density of oocyte and larval Xenopus laevis melanosomes and the isolation of oocyte melanosomes from the eyes of PTU‐treated larvae

Abstract

The buoyant density of melanosomes isolated from oocytes of Xenopus laevis is about 1.88 g/cm³ while most of the melanosomes synthesized in the larvae have a density of about 1.92 g/cm³. The melanosomes isolated from phenylthiourea‐treated larvae or from their eyes have a density of about 1.88 g/cm³. The oocyte melanin of Xenopus was labelled in vivo by injecting the vitellogenic female with ¹⁴C‐DOPA. After these injections, only the melanosomes which band at a density of 1.88 g/cm³, whether from the ovary, normal or PTU‐treated progeny or from the eyes alone of PTU‐treated progeny, were radioactive. It is concluded that the melanosomes found in the eyes of PTU‐treated tadpoles originate in the oocyte.