Experimental gigantism produced by feeding pituitary gland

Abstract

Growth of the individual stops, when the size is reached which is specific for the species to which the individual belongs. The causes which lead to the cessation of growth are not fully known. In man it happens sometimes, that growth continues beyond the normal maximum size of the species; this condition is known as gigantism. Clinical evidence points to the conclusion that at least one form of gigantism is due to an overfunction of the hypophysis gland. Attempts, however, to produce gigantism by feeding hypophysis to animals have been unsuccessful.

The experiments to be discussed presently will show that in salamanders hypophysis feeding produces gigantism and that it is the anterior lobe alone which possesses the ability of maintaining growth after the normal size of the species is reached.

The effect of the hypophysis diet depends, however, on the developmental stage of the salamanders. Larvae do not respond to the anterior lobe diet; the growth-promoting effect of the gland commences after metamorphosis has taken place.

Of the species Ambystoma ofiacum, quite a number of specimens have been kept and measured for several years in my laboratory. In a chart the growth during three years is shown for four specimens; after the first year the animals grow very little and, at certain periods, may show even a decrease in size. The largest animal of this species raised in my laboratory was I 15 mm. long, the largest normal animal in my possession at present is I I 1.5 mm. long. I went through the collections of several museums; the largest specimen I found measured 117.7 mm.; of two breeding females caught recently, one measured I 12 mm., the other one 106 mm.

Of four animals raised in the laboratory from eggs of the same female and kept on a normal diet two were started on the anterior lobe at an age of 62 weeks, about 12 months after metamorphosis and about 4 months after sex maturity had been reached, and two animals were kept as controls.