AGGREGATION OF ERYTHROCYTES (Latin aggregatio — accession) — formation of conglomerates (units) of erythrocytes of different size and density in the conditions of in vivo or in vitro. And. aa. it is possible to observe under a microscope on a slide plate in a fresh drop of blood when there are so-called monetary columns of erythrocytes of which then units are formed, or at biomicroscopic examinations of small blood vessels in which at the same time so-called granular current is observed. Density of units gradually grows, and borders of separate erythrocytes become invisible in a light microscope (homogenization). Process is this reversible, and afterwards units can collapse again (the phenomenon of disaggregation).
And. aa. has a certain value for disturbances of a blood-groove in system of microcirculation (see) since considerably worsens rheological properties of blood in small vessels. Such disturbances can meet, first, at the general strengthening And. aa. in all blood, e.g. at malaria, pneumonia, a shock syndrome, etc., when owing to And. and. there can be obstacles for intake of blood from arterioles in capillary system [Nayzli (M. of Knisely) and sotr.]; secondly, at local strengthening And. aa. in capillaries at the different damaging impacts on fabrics (e.g., in the center of an inflammation).
It becomes a proximate cause of local delay of a blood-groove up to its dead stop in capillaries (see. Staz ).
Intensity And. aa. depends on properties of their surface and of Wednesday, in a cut they are, in particular from quantity and a condition of separate fractions of plasma proteins, in particular fibrinogen and globulins. Neuro and humoral influences on intravascular And. aa. can be carried out by means of impact on it of physiologically active agents, including transmitters of nervous impulses (catecholamines, acetylcholine, a histamine, etc.). One of simple indicators And. aa. speed of their sedimentation can serve in vertical tubes (see Sedimentation of erythrocytes); according to Stokes's formula, than more intensively And. aa., the speed of their sedimentation and vice versa is more.
Bibliography: Voronin V. V. Management of pathological physiology, page 32, Tbilisi, 1947; Mchedlishvili G. and. Microcirculation, page 121. Tbilisi, 1958; To n i in e 1 at M. N. of Intra-vascular erythrocyte aggregation (blood sludge), Handbook physiol., Sec. 2, Circulation, cd. by M. B. Visscher. v. 3, p. 2249, Washington, 1965.
G. I. Mchedlishvili.