Observations on the Blood Vessels of the Vascular Membrane of Chicken Embryos

Abstract

It was the object of these experiments to attempt to discover first, whether there was a difference in innervation between the blood vessels of the vascular membrane of chicken embryos and innervated blood vessels; and second, what changes occurred in the blood vessels of the embryos' vascular membrane during the course of its development. The experiments were carried out in a constant temperature room with eggs at all ages but especially at the 3rd and 4th days of incubation. The eggs were opened at the end of the air-chamber. In connection with innervation both physiological and anatomical investigations were made. In the physiological experiments stimuli of mechanical, electrical and chemical varieties were applied. In the manner of Rickert it was found possible to grade the strength of the stimuli into weak, medium and strong, and doses were found of each variety of stimulus so that comparable effects in the vessels could be observed: constriction or dilatation, but more often dilatation with the weak stimuli, constriction with medium stimuli, and dilatation with the cessation of flow, with strong stimuli. It was characteristic of all these effects, except perhaps those with strong stimuli, that only the vessel or vessels in the immediate neighborhood of the stimulus was affected. The stimulus did not spread to surrounding areas. Adrenalin behaved differently from the case of innervated vessels, for with small doses (0.1 cc. of a 1% solution) no effect on the vessels was observed. With doses 4 times as great, one-half to 4 or 5 minutes were required to bring about contraction. In such cases a like amount of salt solution had the same effect.

In the anatomical experiments sections were made of embryos 3, 4 and 7 days old, and these were stained both by Bielschowsky's method and by the method of methylene blue reduced by rongalit.