Experimental Exophthalmos in the Guinea Pig

Smelser 1 described a stainable infiltrate occurring between the fat cells, muscle fibers, the lobules of the lacrimal gland, and in the connective tissue of the orbit in thyroidectomized guinea pigs injected with thyrotropic hormone. This infiltrate was said to consist of granules and droplets, presumably lipoid, as well as many lymphocytes scattered throughout the tissue. He reported that human biopsy specimens of muscles, orbital connective tissue and fat obtained at operation from 2 low B. M. R. exophthalmos cases showed an infiltration indistinguishable from that obtained experimentally.

In the present study 12 immature guinea pigs whose weights ranged between 232 and 320 gm. were used. In 6 animals a thyroidectomy was done. One intact and one thyroidectomized animal were used as controls. Five intact and 5 thyroidectomized animals were given daily intraperitoneal injections of 25 to 40 guinea pig units of Antuitrin “T”,∗ a potent anterior pituitary gland extract containing the thyrotropic factor separated from the other hormones of the hypophysis. Biopsy of the thyroid gland in 2 instances after 5 injections of the extract revealed a marked hyperplasia. The animals were sacrificed at intervals, after from 10 to 55 daily injections of the hormone. The control animals were sacrificed after 55 days, at the end of the experiment. At autopsy, the orbital contents were removed as one piece of tissue and specimens of skeletal muscle from various parts of the body were taken.

Exophthalmos was judged as having developed in 4 of 5 intact and in 4 of 5 thyroidectomized animals from the seventh to the tenth days of injection. The apparent proptosis was more definite early in the experiment and appeared to be of the same degree in both sets of animals.