Abstract
The technique employed and the optical equipment were the same as those noted in my preceding communication on the contraction of fibrin. 1 The blood was obtained from man, dog, rabbit and guinea pig.
The red corpuscles of all the species examined are round or slightly oval, show a della, and vary somewhat in size. In the human subject the diameter measurements varied between 7.8-9μ; in dog between 7-7.8μ; in rabbit 6-7.8μ; in guinea pigs 6-7.8μ.
The formation of macrocytes occurred as follows in all species: Immediately after the hanging blood-drop is made, laking of red corpuscles begins in the periphery. If 2 corpuscles are touching each other, the area of contact slowly becomes greater until the 2 reds form an oval mass with an encircling median groove. In the middle of this groove a whitish line is seen which represents the opposed or fused surfaces of the 2 corpuscles. When this common septum disappears the 2 corpuscles form a round or slightly oval macrocyte measuring 10μ+ in diameter. As long as the septum exists the macrocyte shows a slight indentation in its outline. (See Fig. 1.) The hemoglobin content is usually the same as that of a normal red corpuscle, which shows that the thickness of the macrocyte is not appreciably greater than that of a normal erythrocyte. No della was ever observed in a macrocyte, nor was this structure seen in sideview.
Macrocytes may also be formed by the fusion of 3 corpuscles or by fusion of a macrocyte with a normal corpuscle. Fusion of component red corpuscles is not always complete; this is readily betrayed by the presence of septa and by the shape.
After formation, the macrocytes sooner or later begin to pale without obvious change in size and finally a macrocytic blood-shadow larger than that of the average blood-shadow is formed.
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