ZONA

(Lat.), n. f. Zon'a3. See ZONE and ZOSTER. Ophthalmic z. See ZOSTER ophthalmic us. Z. arcuata (of the cochlea). The middle section of the membrana basilar is. [F, 3.] Z. cast it at is [Stephanus]. See HYMEN (3d def.). Z. choriacea. The thickened margin of the membrana basilar is where it rests on the lamina spiral is o ea. [L, 31.] Z. denticulata (cochleae). 1. The z. choriacea and the z. intern a of the basilar membrane. 2. Of Deiters, the upper surface of the z. choriacea. [L.] Z. extern a. That portion of the membrana basilar is that is external to the outer rods of Corti. [L.] Z. fasciculata. Of Arnold, the main portion of the cortex of the suprarenal capsule. It lies beneath the z. glomerulosa, and is composed of elongated and column-like anastomosing groups of cells. [C; J, 30.] Z. ganglioiiaris. A large ganglion layer in Rosenthal's canal, lying on the periphery of the modiolus, between the fibrous bundles of the latter and the spiral lamina. [F, 3.] Z. gangreneux (Fr.). A form of zoster in which grayish eschars develop about the vesicles, followed by deep ulceration; occurring usually in the aged or in persons of depraved constitution. [G, 51.] Z. glomerulosa. Of Arnold, the layer of the suprarenal capsule next the fibrous capsule, forming the proper substance of the body of the organ and consisting of oval or rounded ma es of cells that are really the ends of cells of the z. fasciculata. [J, 30.] Z. grannlosa. 1. See Z. radiata (1st def.). 2. Of von Baer, the discus pro liger us. Z. herpetlca. See HERPES per is cel is.Z. ignea. See ZOSTER. Z. incerta. Of Forel, a layer of fine longitudinal nerve-fibres, with a few scattered ganglion-cells, immediately adjoining the reticular formation. [I, 17 (K).] Z. intern a, Z. laevis. The portion of the membrana basilar is that is internal to the outer rods of Corti. [L. 31.] Z. median a. See Z. choriacea. Z. membranacea. See MEMBRANA basilar is. Z. moll is. See LAMINA spiral is membranacea. Z. nerve a. See Z. intern a and Z. choriacea. Z. orbicularls. A thickening of the capsular ligament of the hip joint corresponding to the margin of the acetabulum. [L.] Z. o ea. See LAMINA spiral is o ea. Z. pectin at a (of the cochlea). The external, finely-striated section of the lamina spiral is membranacea. [F, 32.] Z. pellucid a. Fr., zone transparente, membrane ovulaire (ou vitelline). Ger., Dotter haut, Dotterhulle, A, ape; A", at; AS. ah; A, all; Ch. chin; Ch", loch (Scottish); [s. 748]