Histological Changes in Interrenal Tissue of the Goldfish, Carassius aurafus, following X-Irradiation

Goldfish, Carassius auratus, irradiated with 4 kR or more of X-rays and kept at 23•Ž invariably died around 10 days after irradiation, while those exposed to 1 kR or less survived for at least one month under the same temperature condition, without showing any harmful effects. Interrenal cells located in the head kidney of the goldfish decreased in size after hypophysectomy and underwent a hypertrophy following administration of mammalian ACTH. Six to nine days after whole-body irradiation with 1-16 kR of X-rays, interrenal cells were definitely en larged. In hypophysectomized fish a similar X-irradiation failed to cause interrenal cell hypertrophy. Irradiation of the head of goldfish resulted in a hypertrophy of interrenal cells, even if the posterior part of the body containing the head kidney was shielded from X-rays. These findings seem to suggest that, in the goldfish, secretion of ACTH from the hypophysis increases at least for a period following X-irradiation.