Influence of Pineal Body on Melanoma of Hamsters

Abstract

JORDAN^1,2 described the presence of melanic granules in pineal gland of sheep and del Rio-Hortega^3–5 found pigment granules in the pinealocytes of human pineal as well as in other mammals. Santamarina and Meyer Arndt⁶ have more recently shown that the pigment in bovine pineal was true melanin. Ultra-violet spectral curves of bovine pineal melanin showed the same characteristics as those obtained from tyrosine melanin^7,8. Pineal melanin differs slightly, however, from the melanin obtained from the choroid of the ox eye. Administration of pineal extract to tadpoles^9,10, to toads¹⁰ and to fishes¹¹ produces alteration in pigmentation. Thus it is possible that pineal body not only contains melanic pigment but is also capable of inducing some form of change in pigmentation. The hamster pineal body contains pigment granules in abundance (Fig. 1). On the basis of the investigations by Santamarina and Meyer Arndt, these can be assumed to be melanic granules. No data are available at present for the effects of pineal ablation or administration of pineal extract on pigmentation of hamsters. Isolated observations in other species have suggested a possible association between pineal body and pigmentation, however, and therefore a study was undertaken to observe the effect of pineal ablation on the growth and spread of a highly pigmented and spontaneously occurring neoplasm in hamsters.