Myxobacteria

Myxobacteria, or slime bacteria, are found on the manure of herbivorous animals, on decaying wood, etc.; in most cases they form colonies colored yellow or orange. In the development of bacteria, two periods are distinguished: vegetative growth and false fruiting. In the first period, they appear as rods 5-15 μ in length and 1 μ or less in thickness; the rods multiply by division and secrete a large amount of mucus, into which the entire mass of bacteria is incorporated; a so-called false 'plasmodium' is formed. In certain places of such a plasmodium, outgrowths are formed, consisting of mucus and bearing swellings at their ends. The outgrowths represent stalks, and the swellings at their ends represent fruiting bodies; in the latter, in special cysts, there are round or elongated spores approximately 1 μ in diameter; the size of the fruiting bodies is up to 1 mm. From the spores, bacteria develop. The independent existence of myxobacteria is not recognized by all; there are also doubts regarding their classification as bacteria; for this reason, the group M. has at present been named polyangium.

A. Abricosov. Myxoma, myxoma (from Greek myxa - mucus), synonym myxoblastoma, a tumor of mucous tissue, i.e., tissue containing mucin and corresponding to Wharton's jelly of the umbilical cord. It is precisely the presence of mucin (see) that determines the classification of the tumor as true M. and makes it possible to distinguish M. from myxoma-like changes in other tumors; the latter may be based simply on tissue edema with its transformation into a substance resembling mucus but not containing mucin. M. can be primary, i.e., tumors that are primary from the outset and develop from mucous tissue, and secondary, representing the result of true mucous transformation of such tumors as fibromas, lipomas, chondromas, sarcomas. It is even believed that M. of such sequential origin, i.e., secondary M., are more frequent tumors than primary M. The question of which M. are primary and which are secondary is very difficult to solve even when the tumor contains fibrous, fatty, and cartilaginous tissues, since these tissues can also be formed in primary M. (Borst). Such tumors, containing mucous tissue along with the aforementioned tissues, are named depending on the predominance of one tissue or another as myxoma fibromatodes, lipomatodes, chondromatodes, or fibroma, lipoma, chondroma myxomatodes, or myxofibroma, fibromyxoma, myxochondroma, chondromyxoma, etc. True primary M. with certainty include mucous tumors developing from embryonic remnants of mucous tissue, for example M. of the umbilical region, mesentery, wall of the urinary bladder, multiple M. of nerve trunks. On the other hand, the origin of M. arising from subcutaneous tissue, from mucous membranes (for example, the nose), from the endocardium, periosteum, bone marrow, the stromal tissue of the mammary gland (for example, myxoadenomas, which are adenomas with mucous stroma), etc., in terms of their classification as primary M. is controversial. Many of the formations sometimes called M., such as mucous polyps of the nose, uterus, do not belong to tumors but represent inflammatory hyperplasias of the mucous membrane. Some M. of the heart are nothing more than organized thrombi with subsequent tissue edema. The term M. (myxoma chorii) is also incorrectly applied to hydatidiform mole. - M. are nodular, often polypoid (for example, M. of mucous and serous membranes) tumors of soft consistency, grayish-pink in color, very juicy, moist on section, often with secretion of mucus on the section surface. - Microscopically, M. consist of a transparent, mucin-containing ground substance, in which star-shaped, triangular, and spindle-shaped cells characteristic of mucous tissue are visible with thread-like processes; among these elements, leukocytes, lymphocytes, and polyblasts are fairly often found in varying amounts. The tissue of M. is usually very rich in blood vessels; when they are very well developed, one speaks of myxoma angiomatodes. - The course of M. is benign: typical M. do not metastasize and rarely recur after surgery. However, there are M. rich in cells, the latter being polymorphic and containing hyperchromatic nuclei of varying sizes; such tumors, classified as myxosarcomas, exhibit all the signs of malignant course characteristic of sarcomas. Treatment of M. is surgical.

A. Abricosov