Photically induced experimental exophthalmos: role of Harderian and pituitary glands.

Exposure of adult male and female albino rats to high-intensity illumination for 17.5 hr results in a marked, transient exophthalmos, which persists for approximately 48 hr after the light exposure. Upon examination of the Harderian glands in these rats, a significant glandular weight increase was observed up to 2 days after light treatment. Analysis of individual glandular components showed that this weight increase was due to an increase in fluid content of the glands. The lipid and residue contents in the Harderian glands of exposed rats decreased significantly. When animals were hypophysectomized (HYPEX) prior to the short-term illumination period, there was no visible exophthalmos. However, when the Harderian glands were analyzed at necropsy, they had a similar relative increase in weight as compared to glands of intact rats, and this again was the result of increased fluid composition. The exophthalmos induced in intact animals resulting from an enlargement of the Harderian glands seemingly was due directly to a radiant energy-dependent mechanism and not to any pituitary hormone mediation. The edematous phenomenon was similar in Harderian glands of HYPEX rats, but visible exophthalmos was lacking, probably because of the atrophied condition of the glands in the absence of the pituitary.