. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 222 COMPARATIVE ANATOMY repeats the form of the membranous labyrinth, as does also the mesoblast which encloses this space and which later becomes chondrified, and often also ossified. A menibranoios and a lony laby- rinth can thus be distinguished, and between them is a cavity (cat-um 2}erilij7ii2Jhaticum)\ed with a lymph-like fluid (perilymph). The cavity within the membranous labyrinth, which also contains a fluid {endolyniph), is spoken of as the cavum endolympJudicum. Except in Cyclostomes, three semicircular c
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 222 COMPARATIVE ANATOMY repeats the form of the membranous labyrinth, as does also the mesoblast which encloses this space and which later becomes chondrified, and often also ossified. A menibranoios and a lony laby- rinth can thus be distinguished, and between them is a cavity (cat-um 2}erilij7ii2Jhaticum)\ed with a lymph-like fluid (perilymph). The cavity within the membranous labyrinth, which also contains a fluid {endolyniph), is spoken of as the cavum endolympJudicum. Except in Cyclostomes, three semicircular canals aj-e always present, and these lie in planes at right angles to one another. They are distinguished as the anterior vertical, the posterior vertical, and the horizontal {external) canals (Fig. 177). The first and last-named arise from the .portion of the utriculus known as the recessus utriculi, and each has a vesicle-like swelling or ampulla. Fig. 178b.—Longitudinal Section of an Ampulla of (The exact form of the epithelium of the crista is not indicated.) After Hensen. )(, the nerve passing into the connective-tissue of the crista; a, base of semi- circular canal; 6, point of opening of the ampulla into the utriculus ; <•-, the epithelium on the free wall of the ampulla ; d, the auditory hairs. at its origin. The posterior canal also arises with an ampulla from a prolongation of the utriculus (sinus posterior). The other end of the horizontal canal opens by a funnel-shaped enlargement into the utriculus, while that of the anterior and of the posterior canal fuse together to form a common tube, the so-called canal commissure (sinus superior), which also opens into the utriculus. Concretions composed mainly of carbonate of lime are present in the regions of the various nerve end-plates of the auditory organ ia all Vertebrates. These otoliths present the greatest variety both in form and size. The largest and most massive ones are seen in Teleosts. They eit
Size: 2055px × 1215px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
