Granularity

Granularity. In cellular bodies, one can encounter in normality granularities of the most diverse forms, origins, physico-chemical nature, and functional significance. All of them can be divided into 2 main groups: 1) Those appearing as structural components of the cytoplasm, and 2) inclusions of the protoplasm. The first category includes the Altmanian granules discovered in 1890, then so-called chondriosomes and granules of the Golgi apparatus. Scientific currents, which initially studied the Altmanian granules and chondriosomes separately, later merged, as it turned out that these are identical granules. At present, it is considered established that the mentioned granules are a necessary attribute of the cytoplasm of all cells (animal and plant), representing an organelle composed of individual particles. Each particle contains, in addition to complex protein, also a lipid component. There is also evidence in favor of the fact that the elements of the Golgi apparatus and chondriosomal granules are identical (Dogel). The function of chondriosomal granules is problematic, but in any case is closely related to metabolism in the cell; in this respect, its elements are compared with microscopic laboratories scattered in the cytoplasm, where the physicochemical work of the cell is concentrated. For more on the functional and formative-plastic significance of chondriosomes, see Chondriosomes. On the other hand, one can note a whole series of granular formations in the form of cellular inclusions of diverse significance: 1) Reserve nutrients - yolk granules in egg cells, Nissl granules in nerve cells, etc.; 2) Intermediate stages of metabolism in cells - various types of granules in glandular cells, often being preliminary stages of enzyme formation (zymogen granules in the pancreas, secretory granules of salivary glands, preliminary stages of mucus formation in goblet cells, granules in developing fat cells, etc.); 3) Granular deposits existing in cells for an indeterminate long time and being an expression of their special structure and activity (granules in pigment cells); 4) Granules absorbed by cells from intratissue disintegration and finally 5) Granules foreign in composition to the organism (phagocytosed by white blood cells and tissue cells mineral particles in conioses, etc.).--One can also speak of pathological granules, in which cases in some instances these will be pre-existing protoplasmic granules (e.g. chondriosomes) that have undergone certain changes, while in other cases one is dealing with the appearance of special granules that are products of altered metabolism (protein, carbohydrate, fat, mineral). Pathological granules are also found as a result of disintegration of Nissl granules, neurofibrils, myelin, neurokeratin, glial cells. In severe destructive changes of brain tissue, the so-called fibrinoid granules, metachromatic granules (Snesarev), intermediate bodies (Fiillkorper, German authors) are described. Granules in leukocytes. According to Ehrlich's proposal, granules can be classified according to their relation to dyes of a specific chemical nature - acid, basic, neutral; if this classification with respect to tissue cells does not yield practically valuable results, then with respect to leukocytes, the technique of staining with complex dyes (combination of acid with basic), allowing differentiation of granules according to their affinity for specific dyes, gives valuable data for diagnosis and has firmly established itself in clinical practice. One distinguishes acidophilic (eosinophilic), basophilic, and neutrophilic granules (staining in an indefinite tone, a mixture of acid and basic dye); in non-granular white blood cells with this method of staining, azurophilic granules, which stain metachromatically with methylene azure in red color, are also noted.- Granules in erythrocytes. In erythrocytes, one can note small granules that stain vitally with methylene blue, toluidine blue and (especially) brilliant cresyl blue (Cesaris-Demel). In fixed preparations, Jolly bodies, the granulo-fibrillar substance of Italian authors, basophilic granules, marginal granules, Ehrlich-Heinz granules are stained; all these formations are not encountered in normal erythrocytes and stand at the boundary of pathological changes. Regarding their origin, significance, and diagnostic value - see Blood.