Ultrastructural analysis of gene interaction and melanosome differentiation in the retinal pigment cells of the albino goldfish

Abstract

The genotype of albino goldfish is represented by pp,cc, and the non‐albino fish is PP,CC. The P gene begins to control the melanosome formation of retinal pigment cells at St‐21; and the C, which is epistatic to P and p, governs melanosome formation in the dermal melanophores and in retinal pigment cells after St‐22. Then in the pp,CC fish, between St‐21 and St‐22, melanosomes of the pigmented retina are albino in type, but after St‐22 they become non‐albino in type. From ultrastructural observations on the melanosomes of these late‐melanizing fish, it is apparent that the incompletely melanized albino pigment granules can differentiate into normal melansomes under the control of the C gene. The processes of melanosome maturation in the late‐melanizing goldfish are evident from these observations.