In osteomalacia and in the absorption of bone the mucous degeneration of the bone-cartilage plays an important part. The lime salts are first set free, and the cartilage then undergoes a mucous degeneration; the product is either absorbed or remains as a liquid within cavities of large or small size. The mucous metamorphoses of fibrous and fat-tissues, likewise of bone-marrow, are well recognized instances of the occurrence of a mucous transformation of the intercellular substance of connective tissues. Finally, clotted fibrin, so often met with as the product of the inflammation of serous surfaces, may undergo a mucous metamorphosis, and, thus transformed, offer a suitable material for absorption.
Colloid Degeneration, Colloid Metamorphosis.
Laennec used the term colloid in a descriptive sense to indicate a gelatinous appearance, and for a long time its use was thus restricted. As the colloid appearances were found to differ in their chemical reaction, their distribution, and their pathological importance, and as the term was further extended to include appearances seen with the microscope, it obviously became necessary to subdivide the colloid series of changes according to the observed differences. Its use is now limited to those gelatinous conditions or appearances due to the presence of a fixed albuminate, homogeneous or finely granular, translucent, colorless or pale yellow, of varying consistency, which does not become fibrillated on the addition of acetic acid, and which does not change in color when acted upon by iodine. This albuminate is considered in most instances to represent the result of a transformation, a metamorphosis of cells, and is associated with an impairment of their function—a degeneration which is progressive, and leads, sometimes, to the destruction of the organ, as occurs in certain instances of colloid degeneration of the thyroid body. Usually, the process is limited, affecting particular parts rather than the whole of an organ. The reaction presented by a solution of sodium albuminate in the presence of neutral salts leads to the view that colloid material may represent a coagulation of an albuminous substance or substances under favoring conditions. The presence of colloid masses in the kidney thus meets with a plausible explanation.
The place of its typical occurrence is the thyroid body in certain cases of goitre, and it is early met with as a homogeneous substance replacing the granular cell-protoplasm. With its increase the latter disappears, and the entire cell is transformed into a homogeneous sphere. At times the colloid substance may be seen to project from the surface of the cell as a pale rounded clump. The aggregation of these clumps results in the presence of masses of various size, in which may be found granules of fat or pigment and crystals of cholesterin, which are accidental, not essential. Colloid masses are sometimes met with—in lymphatic glands, for instance—as concretions, mulberry-like aggregations of stratified colloid bodies, which may be infiltrated with earthy salts. Colloid material may eventually become liquefied, transformed into a sodium albuminate; and the presence of cysts in certain varieties of goitre is thus explained. The coexistence in the kidney of colloid accumulations and watery cysts has led to the view that the latter may, under certain circumstances, result from the former through the liquefaction of the colloid material. The same view is held with regard to the origin of cysts frequently met with in the choroid plexuses.
The colloid metamorphosis of cells is also to be found in the epithelium of mucous membranes and their glands, in the prostate, suprarenal capsule, sebaceous glands of the skin, and in the cells of certain tumors.
Amyloid Degeneration, Amyloid Infiltration, Waxy Degeneration, Lardaceous Degeneration.
The colloid appearances due to the amyloid degeneration of cells are of the greatest clinical importance from their frequent occurrence and the gravity of the symptoms connected with their presence. In amyloid degeneration there is the transformation of the cell-protoplasm into an albuminous material different from other albuminates found in the body. This transformation is at the expense of the functional activity of the cell, and the latter becomes inert. Amyloid degeneration represents no mere substitution, but an addition, since the affected tissue is increased in volume. The albuminate was called amyloid by Virchow in consequence of its color-reaction with iodine. Its method of origin is wholly unknown, never being found in the circulating fluids nor in articles of food. It is met with chiefly in the cell, although its presence in the intercellular substance of old people is recognized, and its occurrence in the midst of the thrombotic deposition on inflamed valves and in the results of inflammatory processes is also recorded.
At present the question is under discussion whether the amyloid degeneration may affect cells of the most varied character, or whether it is limited to those of connective tissues. Eberth35 maintains that in all cases the amyloid disturbance is seated in the connective tissue. Kyber,36 the latest investigator, in opposition to this view maintains that this affection is not limited to the connective tissue, but may also be seated in the parenchymatous cells of organs. Whether the one of these views is to exclude the other, or whether both are not correct, remains for future investigation to decide.
35 Virchow's Archiv, 1880, lxxx. 138; 1881, lxxxiv.
36 Ibid., 1880, lxxxi. 7, 111.