Forbes M S, van Neil E E
Department of Physiology, University of Virginia School of Medicine, Charlottesville 22908.
Anat Rec. 1988 Dec;222(4):362-79. doi: 10.1002/ar.1092220409.
The structure and quantitative contribution of membrane systems (transverse-axial tubular system [TATS] and sarcoplasmic reticulum [SR]) have been investigated in the heart of the adult guinea pig. Although previous quantitative studies have been made of guinea pig myocardium, this is the first such study that has utilized tissue in which membrane system elements were clearly identified by selective staining (in this case by the osmium-ferrocyanide [OsFeCN] postfixation method). Both membrane systems are highly developed in ventricular cells, but a TATS is essentially absent from atrial myocytes. The ventricular TATS consists principally of large-bore elements which may be oriented transversely, axially, or obliquely, making numerous anastomoses with one another to form a highly interconnected system of extracellular spaces that penetrate to all myoplasmic depths of the ventricular cell. The cell coat that lines the lumina of these tubules is structured, containing fibrillar structures that run along the length of the tubule. The volume fraction (VV) of the ventricular TATS is low (2.5-3.2%), in consideration of the qualitative prominence of the TATS in these cells. The relative total population of sarcoplasmic reticulum is higher in the atria (VV of 10-11%) than in the ventricles (VV of ca. 8%). In all guinea pig myocytes, several major structural divisions of SR can be discerned, which include network SR, junctional SR, corbular SR, and cisternal SR. Junctional SR (J-SR) in the atrial cells is limited almost exclusively to peripheral saccules of junctional SR (PJSR), whereas both interior J-SR and PJSR are present in the ventricle. Two distinct morphological types of PJSR appear in atrial cells, including both flattened and distended saccules, the latter resembling PJSR of lower vertebrate heart. Spheroidal bodies of SR with opaque contents (corbular SR) are prominent at or near Z-line levels of the sarcomeres of atrial and ventricular cells. Cisternal SR is likely a subset of network SR, but some examples appear related to rough endoplasmic reticulum. An overall impression obtained from this study is that guinea pig atria are composed of structurally primitive cells, whereas the ventricular cardiac muscle cells are more highly developed entities.
在成年豚鼠心脏中，对膜系统（横向 - 轴向管状系统 [TATS] 和肌浆网 [SR]）的结构和定量贡献进行了研究。尽管先前已对豚鼠心肌进行过定量研究，但这是首次利用通过选择性染色（在本研究中采用锇 - 亚铁氰化物 [OsFeCN] 后固定法）能清晰识别膜系统元件的组织进行此类研究。两种膜系统在心室细胞中都高度发达，但心房肌细胞中基本不存在TATS。心室TATS主要由大口径元件组成，这些元件可横向、轴向或倾斜排列，相互之间形成大量吻合，构成一个高度互连的细胞外间隙系统，该系统可穿透到心室细胞的所有肌浆深度。衬于这些小管腔的细胞衣具有结构，含有沿小管长度延伸的纤维状结构。考虑到TATS在这些细胞中的定性突出程度，心室TATS的体积分数（VV）较低（2.5 - 3.2%）。肌浆网的相对总体积在心房中（VV为10 - 11%）高于心室（VV约为8%）。在所有豚鼠心肌细胞中，可辨别出SR的几个主要结构分区，包括网络状SR、连接性SR、球状SR和池状SR。心房细胞中的连接性SR（J - SR）几乎完全局限于连接性SR的外周囊泡（PJSR），而心室中既有内部J - SR也有PJSR。心房细胞中出现两种不同形态类型的PJSR，包括扁平囊泡和扩张囊泡，后者类似于低等脊椎动物心脏的PJSR。在心房和心室细胞肌节的Z线水平或附近，含有不透明内容物的球状SR体（球状SR）很突出。池状SR可能是网络状SR的一个子集，但有些例子似乎与粗面内质网有关。从这项研究中得到的总体印象是，豚鼠心房由结构原始的细胞组成，而心室心肌细胞是更高度发达的实体。
