Lobularity

LOBULARITY, lobule, lobe. The term lobe (Latin lobus) refers to individual parts of whole organs that possess an identical histological structure and the same physiological function of their specific parenchyma. The relative isolation of lobes in organs is manifested through depressions on the surface of the latter, bearing the name of sulci or fissures (Latin sulcus, incisura). The totality of lobes is united in the organ as a whole by means of a common capsule that is not interrupted in the depth of the fissures, common excretory ducts, as well as blood vessels and nerves. The lobularity of organs is subject to certain variations in individuals of a given species. In the history of the development of the individual and of species, quantitative changes also take place in the form of an increase or decrease in the number of lobes of certain organs; moreover, in accordance with Haeckel's biogenetic law, these tendencies toward a decrease or increase in the number of lobes proceed in parallel both in individual development (ontogeny) and in the development of species (phylogeny). Thus, the number of brain lobes tends to increase in both the first and second cases; conversely, the lobularity of the kidneys decreases. It is necessary to distinguish the lobularity of organs as a variational and phylogenetic manifestation in the development of organisms from lobularity acquired in connection with diseases in intrauterine and extrauterine life, which includes, for example, the lobularity of the liver in syphilis (hepar lobatum syphiliticum), in prolonged constriction and compression of the liver with atrophy of the parenchyma and the formation of fissures on its surface (German Schnurfurche); the separation of parts of the spleen after extensive infarcts, and the like. The direction and character of the fissures, the presence of scars on the capsule of the organ, the irregular and excessive development of cicatricial connective tissue, along with parenchymatous changes, make it possible to distinguish between true and false lobularity. In addition to lobes, one distinguishes l o b u l e s (Latin lobulus) as constituent parts of lobes in organs and certain tissues. Anatomically, lobules are demarcated from each other by a greater or lesser amount of connective tissue surrounding the parenchyma and carrying within itself the interlobular ducts, vessels, and nerves. Examples are the lobules of the liver, lungs, adipose tissue, and the like. The lobular structure of organs and tissues is reflected in the development of pathological processes. The relative morphological isolation and physiological independence of lobes and lobules lead to the fact that pathological processes often have a focal character of either lobar or lobular dimensions, as occurs, for example, in lobar and lobular pneumonias. Lobular structure is an important factor in the processes of regeneration of the parenchyma of affected organs, wherein the destroyed parenchyma of some lobules is restored at the expense of the parenchyma of other, unaffected ones.

G. Koritsky.