Hamlett W C, Schwartz F J, Schmeinda R, Cuevas E
South Bend Center for Medical Education, Indiana University School of Medicine, University of Notre Dame 46556, USA.
J Exp Zool. 1996;275(2-3):83-94.
We report here on the anatomy, histology, and development of the three sets of cardiac valves in embryonic and adult elasmobranch fishes. The sinus venosus is the first segment of the heart to receive blood, and a pair of sinoatrial (SA) valves prevent backward flow of blood into the sinus venosus. The SA valves derive from two dorsolateral infoldings of the cardiac wall and consist of a simple endocardium covering transverse sheets rich in collagen. The SA valves are simple flaps of tissue without papillary muscles or chordae tendineae. Blood from the atrium passes the atrioventricular (AV; semilunar) valves, which are attached to papillary muscles in the ventricle by way of the chordae tendineae. A series of rows of conal or pocket valves (CV) in the conus arteriosus, equipped with chordae tendineae but no papillary muscles, prevent blood from reentering the ventricle. Chordae tendineae form in a similar fashion in both chambers. Elevations from the chamber wall emerge as a sheet covered on both surfaces with endocardium and separated by a core of connective tissue. Endocardial cells extend basal projections toward the opposing epithelium through their basal laminae. Basal cell projections make contact to create perforations that enlarge to produce spaces between the nascent chordae. Fibroblasts in the core of the chordae enlarge and strengthen the chordae by producing linear arrays of collagen fibers.
我们在此报告胚胎期及成年软骨鱼类三套心脏瓣膜的解剖结构、组织学特征及发育情况。静脉窦是心脏接收血液的第一部分，一对窦房（SA）瓣可防止血液倒流回静脉窦。SA瓣源自心脏壁的两个背外侧褶皱，由覆盖富含胶原蛋白的横向薄片的单层内膜组成。SA瓣是简单的组织瓣片，没有乳头肌或腱索。来自心房的血液通过房室（AV；半月形）瓣，该瓣膜通过腱索附着于心室的乳头肌上。动脉圆锥中有一系列成排的圆锥或袋状瓣膜（CV），它们配有腱索但没有乳头肌，可防止血液重新进入心室。腱索在两个腔室中以相似的方式形成。腔室壁上的隆起形成一层两面都覆盖有内膜且由结缔组织核心分隔的薄片。内膜细胞通过其基膜向相对的上皮延伸基底突起。基底细胞突起相互接触形成穿孔，穿孔扩大后在新生腱索之间产生间隙。腱索核心中的成纤维细胞通过产生线性排列的胶原纤维来扩大和强化腱索。
