Observations on the Contraction of Fibrin in Blood

Abstract

The hanging-drop method was employed exclusively, with aseptic precautions. The blood preparation was sealed with sterile vaseline. The optical equipment consisted of a Zeiss apochromat microscope; objective 3 mm. 1.4 N.A. oil immersion gave the best results, though the 2 mm. 1.3 N.A. is satisfactory. The light source was a Zeiss filament lamp. The blood was taken from the human subject, dogs, rabbits, and guinea pigs; the results noted in the different animal species are practically the same; those reported here are based on approximately 100 different preparations. Each observation lasted between one and 6 hours. The observations were made at room temperature; the coagulation time varied in the different bloods; those clotting with moderate rapidity were most suitable for study.

Observation of the edges of the blood-drop sooner or later shows in some area a distortion of the oval or round red corpuscles by fibrin threads which have anchored themselves to the periphery of the corpuscle. These fibrin filaments generally stretch at right angles to the periphery of the drop and appear attached to the serum edge of the drop (often to a blood-shadow) and to the main body of the blood-drop itself. Commonly 2 fibrin filaments are cemented to opposite sides of a corpuscle and the corpuscle then assumes a spindleshape due to contractin of the fibrin filaments. The fibrin threads may appear short at first, 5μ and less, and may seem to end in the clear serum. Gradually more of the fibrin filament becomes visible, at times showing a length of 40μ; the section adjacent to the red cell thickens somewhat in diameter, becoming occasionally slightly fuzzy in outline and this same portion may show a faint diagonal striation.