Webb S, Brown N A, Wessels A, Anderson R H
Department of Anatomy and Developmental Biology, St. George's Hospital Medical School, London, UK.
Anat Rec. 1998 Mar;250(3):325-34. doi: 10.1002/(SICI)1097-0185(199803)250:3<325::AID-AR7>3.0.CO;2-Z.
Arguments concerning the development of the pulmonary vein, and its relationship to the embryonic venous sinus (sinus venosus) have continued for well over a century. Recently, attention has again been focused on the origin of the pulmonary vein. It has been suggested that, whereas the pulmonary vein originates from the left atrium in humans, in all other vertebrates it originates from the venous sinus, with subsequent transfer to the left atrium. The nature of this transfer has not, however, been elucidated, although there is speculation that the pulmonary vein is "pinched off" from the left side of the embryonic venous sinus.
We studied closely staged hearts of normal mouse embryos from a C57BL/6 x CBAcross days 10 and 11 of gestation (plug day = day 1). Two series of embryos were collected and fixed in 2% glutaraldehyde, 1% formaldehyde, buffered with 0.05 M sodium cacodylate pH 7.4 (adjusted to 330 mOsm with NaCl). One series was wax embedded, serially sectioned, and stained with Masson's trichrome. The second series was subject to microdissection and scanning electron microscopy.
The atrial component of the heart tube is attached to the body of the embryo by reflections of the atrial myocardial wall. The attachment can be considered, from the outset, as the heart stalk, with the myocardial-mesodermal connections forming a horseshoe of tissue that projects ventrally into the lumen of the atrium, surrounding a single evagination in the midline of the embryo. This heart stalk is cranial to the connections of the tributaries of the embryonic venous sinus and ventral to the foregut. When traced through its developmental stages, the evagination in the centre of the stalk, which we describe as the pulmonary pit, is seen to become the portal of entry for the developing pulmonary vein.
The heart stalk, representing the area used by the pulmonary vein to gain access to the heart, and analogous to the dorsal mesocardium, is, from the outset, discrete from the area occupied by the orifices of the horns of the embryonic venous sinus. The pulmonary vein does not, in the mouse, develop from the tissues that form the walls of the tributaries of the systemic venous sinus. Comparisons with other studies suggest that early events in the development of the pulmonary vein are likely to be the same in all mammals, including humans.
关于肺静脉的发育及其与胚胎静脉窦的关系的争论已经持续了一个多世纪。最近，人们再次将注意力集中在肺静脉的起源上。有人提出，人类的肺静脉起源于左心房，而在所有其他脊椎动物中，它起源于静脉窦，随后转移至左心房。然而，尽管有人推测肺静脉是从胚胎静脉窦的左侧“掐断”的，但这种转移的本质尚未阐明。
我们仔细研究了来自C57BL/6与CBA杂交的正常小鼠胚胎在妊娠第10天和第11天（交配日=第1天）的不同发育阶段的心脏。收集了两批胚胎，并用0.05M 二甲胂酸钠（pH 7.4，用氯化钠调整至330mOsm）缓冲的2%戊二醛和1%甲醛固定。一批进行石蜡包埋、连续切片，并用马松三色染色法染色。另一批进行显微解剖和扫描电子显微镜检查。
心管的心房部分通过心房心肌壁的折返与胚胎体相连。从一开始，这种连接就可被视为心蒂，心肌-中胚层连接形成一个马蹄形组织，该组织向腹侧伸入心房腔，围绕胚胎中线的一个单一的内陷。这个心蒂位于胚胎静脉窦分支连接的头侧，前肠的腹侧。当追踪其发育阶段时，可以看到心蒂中央的内陷，我们将其描述为肺凹，成为发育中的肺静脉的入口。
心蒂代表肺静脉进入心脏所利用的区域，类似于背侧心内膜，从一开始就与胚胎静脉窦角口所占据的区域分开。在小鼠中，肺静脉并非由形成体静脉窦分支壁的组织发育而来。与其他研究的比较表明，包括人类在内的所有哺乳动物，肺静脉发育的早期事件可能是相同的。
