Lamers W H, Virágh S, Wessels A, Moorman A F, Anderson R H
Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, The Netherlands.
Circulation. 1995 Jan 1;91(1):111-21. doi: 10.1161/01.cir.91.1.111.
Some of the problems concerning the origin of the inlet component of the definitive right ventricle were resolved in a previous study in which we showed it to be derived exclusively from the embryonic right ventricle. Questions remain, however, concerning the relative contributions of endocardial cushion tissue and myocardium to the definitive valvar apparatus guarding the right atrioventricular orifice and the origin of the valvar leaflets.
The formation of the tricuspid valve was studied by scanning electron microscopic and immunohistochemical techniques. Concurrent with the development of the right atrioventricular connection, a myocardial ridge forms at the boundary between the atrioventricular canal and the embryonic right ventricle. It grows to become a myocardial gully that funnels atrial blood beneath the lesser curvature of the initial heart tube toward the middle of the right ventricle. Fenestrations in the floor of the gully create an additional inferior opening in the funnel, transforming its initial anterior rim into the septomarginal trabeculation. The septum formed by the fusion of the endocardial ridges of the outflow tract becomes myocardialized in its inferior portion to form, in part, the outlet septum and, in part, the supraventricular crest. The smooth atrial surface of the tricuspid valvar leaflets develops from endocardial cushion tissue. The leaflets become freely movable, however, only after delamination of the tension apparatus within the myocardium. The inferior and septal leaflets derive from the gully and the ventricular septum, their delamination being a single, continuous process. The antero-superior leaflet forms by delamination from the developing supraventricular crest.
The leaflets of the tricuspid valve develop equally from the endocardial cushion tissues and the myocardium. The myocardium contributing to the valve comes from two sources, the tricuspid gully complex and the developing supraventricular crest. These findings facilitate the understanding of several congenital malformations.
在之前的一项研究中，关于终末右心室入口部分起源的一些问题得到了解决，我们在该研究中表明它完全源自胚胎期的右心室。然而，关于心内膜垫组织和心肌对守护右房室口的终末瓣膜装置的相对贡献以及瓣膜小叶的起源，仍存在问题。
通过扫描电子显微镜和免疫组织化学技术研究了三尖瓣的形成。在右房室连接发育的同时，一条心肌嵴在房室管与胚胎期右心室之间的边界处形成。它生长成为一条心肌沟，将心房血液在原始心管的小弯下方引向右心室中部。沟底部的小孔在漏斗中形成一个额外的下部开口，将其最初的前缘转化为隔缘肉柱。由流出道的心内膜嵴融合形成的隔膜在其下部心肌化，部分形成流出道隔膜，部分形成室上嵴。三尖瓣小叶光滑的心房面由心内膜垫组织发育而来。然而，只有在心肌内的张力装置分层后，小叶才会变得可自由活动。下小叶和间隔小叶源自沟和室间隔，它们的分层是一个单一的连续过程。前上小叶通过从发育中的室上嵴分层形成。
三尖瓣小叶由心内膜垫组织和心肌同等发育而来。构成瓣膜的心肌来自两个来源，三尖瓣沟复合体和发育中的室上嵴。这些发现有助于理解几种先天性畸形。
