My.co.plas'ma. Gr. mas.n. myces a fungus; Gr. neut.n. plasma something formed or molded, a form; M.L. neut.n. Mycoplasma fungus form. It has proved difficult to interpret properly the significance of the morphological details and the mode of growth of these organisms. Elementary bodies have been observed both in fluid and solid media; these elementary bodies extrude one or more filaments of varying lengths that ramify to form an apparently unicellular, branching, mycelioid structure. At a later stage of growth tiny endomycelial corpuscles develop in the filaments by a process of successive condensations and constrictions, the formation of septa not being demon- strable. The homogeneous, coenocytic filaments thus become transformed into chains of close-set, spherical bodies which, upon fragmentation of the chains, are liberated as free elementary bodies. These elements are extremely plastic and, under certain growth condi- tions, may develop into peculiar forms, among which are the so-called "large bodies." Some workers claim to have observed various other deviating growth forms, including mul- tiplication by simple budding. Granules may form in the large bodies and, according to some observers, after rupture of the membrane, begin the "life cycle" anew as elementary bodies. In contrast to this, however, there are others who regard the large bodies as repre- senting a stage of involution and degradation. The basic reproductive units, the elementary bodies, are filterable and have a particle diameter of 125 to 250 millimicrons. Gram-negative. Stain poorly with the ordinary bacterial stains, but fairly well with that of Giemsa. Non- motile. Colonial growth on solid media is quite characteristic: the minute colonies have an opaque, granular, brown or yellowish central area growing down into the agar; the central area is surrounded by a translucent, flat zone of variable size. Certain species produce small, black dots consisting of deposits of calcium and magnesium soaps; these occur be- neath and around the colonies together with a crinkled, grayish film. Growth in semi-solid or fluid media is granular or smooth and fluffy. With the exception of the saprophytic spe- cies, all species require enrichment with serum or ascitic fluid for growth on artificial media. Aerobic to facultatively anaerobic; certain species prefer anaerobic conditions. From human and animal sources; one saprophytic species is known. The type species is Mycoplasm,a mycoides (Borrel et al.) Freundt. Key to the species of genus Mycoplasma. I. Parasitic to pathogenic. A. From animals other than man. 1. From mammalian sources. a. From mammals other than rodents, b. From ruminants. c. Acid from glucose. 1. Mycoplasma mycoides. cc. No acid from glucose. d. Growth occurs throughout semi-solid media. 2. Mycoplasma bovigenitalium. dd. Growth preferably near the surface of semi-solid media. 3. Mycoplasma agalactiae. bb. From non-ruminants. c. From carnivores. d. Film and spots not produced on horse-serum agar, e. Poor growth on rabbit-serum agar. 4. Mycoplasma spumans. ee. Good growth on rabbit-serum agar. 5. Mycoplasma canis. dd. Film and spots produced on horse-serum agar. 6. Mycoplasma maculosum. cc. From omnivores. 7. Mycoplasma hyorhinis.
