How the Period of Exposure to Different Stress Stimuli Affects the Endocrine and Lymphatic Gland Weights of Young Chickens

Abstract

AWIDE variety of stress stimuli employed in this laboratory have culminated in essentially the same effect for young chickens; namely, an adrenal enlargement which was accompanied by an involution of lymphatic tissue. In some instances, the period of exposure to the various stimuli employed was found to affect the magnitude of these changes. This observation prompted a series of studies designed primarily to consider more fully these time relationships in the stress response. The stress stimuli utilized for this investigation were: cold, hypo- and hyperthyroidism, and reduced atmospheric pressures.Cold is perhaps the most common condition of stress encountered by living organisms. Survival in extreme cold for most animals is dependent upon the occurrence of a number of physiological adjustments. As reported by Hoffmann and Shaffner (1950), the metabolic rate and thyroid activity of chickens increase following exposure to cold. Numerous investigators have shown that exposure to cold causes many …