Abstract
The spleens of living mice, rats, rabbits, guinea pigs and cats were transilluminated 1 and observed at several magnifications, as high as 600 × (water immersion). Each type of spleen was completely delivered through a long paracostal incision and placed in a suitable celluloid chamber, on a light table, above the abdominal wall. By this means, respiratory motions were eliminated in some, and greatly reduced in all specimens. The spleen, thus supported, was totally immersed in rapidly flowing Ringer-Locke solution at 37°-38°C. Anesthesia hypodermoclyses of sodium iso-amyl ethyl barbiturate (sodium amytal, Lilly) provided adequate narcosis without disturbing the animal's position. Methods were devised for variously stimulating the spleen during the period of observation. The albino mouse was studied in greatest detail. It was noted, however, that the circulatory mechanisms of all species investigated presented fundamental similarities, which seemed to justify the following generalizations.
The afferent capillaries of the pulp communicate with naked pulp spaces at the point where their terminations are marked by ampullary dilatations and diminished mural retractility. No preformed, intactly lined connections between the arterial and venous systems in the spleen have been as yet conclusively demonstrated in our preparations. The break in vascular continuity is obvious in a relaxed or distended spleen, where the walls of the pulp channels are seen to be composed of spherical, oval or polyhedral cells and vague, linear shadows, suggestive of reticulum fibers; but, when the spleen is contracted, it is difficult to detect, because the residual channels, surrounded by compressed pulp cells, then assume the appearance of completely walled vessels, connecting arterial capillaries with venous sinuses and intralobular veins.
The capacity of the pulp is a function of capsular contraction, which takes place rhythmically as well as in response to specific stimulation.
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