Erythrophores and xanthophores in integuments of fish are considered to contain both pteridines and carotenoids as a source of their pigmentation (Bagnara, 1966; Hama and Kajishima, 1967). Ultrastructural studies have indicated that pteridines were localized in pteridine-containing vesicles, or "pterinosomes" (Matsumoto, 1965), and carotenoids were dissolved in small electron-dense particles (Takeuchi and Kajishima, 1972).
Pterinosomes are spherical or somewhat ellipsoidal in shape, ranging in diameter about 0.4μ to 1.0μ. Two types of pterinosomes of different inner structures have been reported (Obika, 1973); the one found in goldfish xanthophores contained irregularly arranged fibrillar materials (Matsumoto and Obika, 1968; Takeuchi and Kajishima, 1972), and the other encountered in erythrophores of the swordtail, Xiphophorus helleri, and also in xanthophores of the medaka, Oryzias latipes, had well-arranged concentric lamellae (Matsumoto, 1965; Kamei-Takeuchi et al. 1968; Kamei-Takeuchi and Hama, 1971). It would seem reasonable, however, to expect that many other morphologically distinct types of pterinosomes could be found elsewhere. This report describes the fine structure of pterinosomes in erythrophores of the guppy.

У домовых мышей на 17-й хромосоме встречается «эгоистичный» фрагмент ДНК — гаплотип t, в гомозиготном состоянии ведущий к смерти или стерильности. Гаплотип t обеспечивает себе эксклюзивное право на размножение, обездвиживая сперматозоиды, его не содержащие.