Chondromucoid

CHONDROMUCOID, a protein from the group of glycoproteins, which is part of cartilage tissue; upon hydrolysis, it breaks down into protein and chondroitin-sulfuric acid. Its composition is: C-47.30%, H-6.42%, N-12.58%, S-2.42%, O-31.28% (Mbgpeg). Part of the sulfur is bound loosely and is cleaved by the action of alkali, part is cleaved in the form of sulfuric acid when boiled with acids. Chondromucoid is digested with difficulty by pepsin with HCl, and an undigested residue always remains, which, like the resulting albumoses, contains an acid close to chondroitin-sulfuric acid. Chondromucoid is easily digested by trypsin. The chondroitin-sulfuric acid formed during the hydrolysis of chondromucoid is a paired ester-sulfuric acid, formed from chondroitin, a substance that yields glucuronic acid, chondrosamine (aminogalactose) and acetic acid upon hydrolysis. The bond between the residues of these substances in the chondroitin-sulfuric acid molecule may be expressed by the following formula: residue of sulfuric acid CH_a-O.SO₂-OH CH_a-HOSO_a %*. no-sn n-s - o n-s- residue of acetic acid H CH₃-CO-NH -----O- H C OH I C- OH I

OH H . . n-s-c-c-c-c-c-coon nonn n residue of glucuronic acid n OH n n Free chondroitin-sulfuric acid decomposes very easily; its salts are almost all soluble in water. From neutral solutions, it precipitates upon the addition of zinc chloride, basic lead acetate, ferric chloride, and alcohol in the presence of salts. In addition to chondromucoid, chondroitin-sulfuric acid has been found in free form in the tunica intima of the aorta, in bone tissue in small amounts, in the sclera, in the urine of humans and horned cattle, and in tendons. When acidified solutions of alkali salts of chondroitin-sulfuric acid are added to a protein solution, the latter precipitates. M. Karyagin. CHORDOMA (chordoma), a rarely occurring tumor that develops from the remaining remnants of the notochord (chorda dorsalis). First, Virchow drew attention to the presence of sometimes a small translucent tumor in the area of Blumenbach's clivus of the base of the skull or on the soft meninges of the pons Varolii or medulla oblongata, consisting of vacuolated cells (physalides). Virchow considered this tumor to be a cartilaginous tumor originating from the spheno-occipital synchondrosis and named it ecchondrosis physalifera. Later, Müller, Klebs, and especially Ribbert and Steiner, as well as Link, clarified that this tumor does not originate from cartilage, but from the remnants of the notochord. Chordoma is most often found on the clivus Blumenbachii, developing from the body of the occipital or sphenoid bone and perforating the dura mater. It is often closely fused with the soft meninges and when the brain is removed, it is found located on the stem part of the latter. More rarely, chordoma develops in the area of the sacrum or coccyx, at the base of the skull, in the cervical or thoracic parts of the spine, e.g., on the anterior surface of the body of one of the cervical vertebrae. Cases of localization of chordoma outside the vicinity of the spine are always questionable in terms of whether the described tumors belong to chordoma (the chordoma of the jaw in a newborn, described by Koritsky, is currently treated as a myoma from myoblasts). Usually, chordoma has the size of a pea or a forest nut; very rarely it reaches the size of a chicken egg, an orange. The tumor is translucent, as if mucous, and consists of vacuolated, as if protoplasm-free cells of 30-40 μ in size; these cells are closely adjacent to each other or between them there are layers of a mucoid substance. The course of such a chordoma is benign and it is often discovered only as an accidental finding during autopsy; however, sometimes chordoma grows progressively and destroys bone (e.g., the sacrum). In addition to such a benign chordoma, there is a malignant chordoma, which reaches large sizes and shows a clear destructive growth and the ability to give metastases. Microscopically, malignant chordoma consists of smaller cells with compact protoplasm containing glycogen; among these cells, physalide cells are also usually found; between the cells there is a mucoid interstitial tissue. Link believes that the tissue of malignant chordomas resembles the tissue of the notochord of the early period of embryonic development.