ANATOMY AND HISTOLOGY OF THE CARDIAC CONAL VALVES OF THE ADULT DOGFISH (SCYLIORHINUS-CANICULA)

Citation
V. Sanscoma et al., ANATOMY AND HISTOLOGY OF THE CARDIAC CONAL VALVES OF THE ADULT DOGFISH (SCYLIORHINUS-CANICULA), The Anatomical record, 241(4), 1995, pp. 496-504
Citations number
30
Categorie Soggetti
Anatomy & Morphology
Journal title
ISSN journal
0003276X
Volume
241
Issue
4
Year of publication
1995
Pages
496 - 504
Database
ISI
SICI code
0003-276X(1995)241:4<496:AAHOTC>2.0.ZU;2-C
Abstract
Background: Knowledge of the structural arrangement of the cardiac con al valves in Elasmobranchs is scarce, The present study was designed t o assess the anatomical and histological features of the conal valves of the dogfish as a starting point for further investigation of the me chanical properties of these valves. Methods: The sample examined cons isted of 31 adult dogfishes, The study was carried out using scanning electron microscopy and histological techniques for light microscopy. Results: In the dogfish, the conus arteriosus contains two transverse rows of valves. The anterior row lies at the level of the conus-ventra l aorta junction and is composed of three valves of similar size. The posterior row is near the conus-ventricular junction and consists of f our valves, one of them very reduced in size, Each valve shows two com ponents, namely, the leaflet and its supporting structure, the sinus. In the anterior valves, the length of the leaflets between their later al attachments to the sinus wall is remarkably longer than the straigh t-line distance between the points of attachment. This allows each lea flet to close against the other two leaflets of the same row, even whe n the conus is relaxed. The leaflets of the posterior valves are ancho red to the conus wall by means of tendinous cords and cannot practical ly bridge the lumen of the relaxed conus. Each leaflet has a stout cen tral body in which the connective tissue is stratified in three layers : outer fibrosa, spongiosa, and inner fibrosa. The lateral parts of th e leaflet mainly consist of a single fibrous layer that bifurcates int o the outer and inner fibrosa layers of the central body. The sinus wa lls of the posterior valves are entirely made up of conal tissue, wher eas those of the anterior valves incorporate an aortic component. Conc lusions: The present findings suggest that the inner fibrosa and the f ibrous lateral portions of the leaflets mainly bear the stress of pres sure generated by blood backflow. The stretching of the leaflets in th e radial direction may basically depend on the spongiosa, whereas the outer fibrosa determines the radial stiffness of the leaflets. (C) 199 5 Wiley-Liss, Inc.