David H, Marx I
Z Mikrosk Anat Forsch. 1977;91(4):709-36.
In order to characterise the postnatal development and maturation of heart muscle cells the musculature of the left ventricle of male rats has been investigated electronmicroscopically at birth, at the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 14th, and 21st day of life, as well as after the 1st, 2nd, 3rd, 4th, 5th, 6th month. On the basis of these investigations quantitative and qualitative data have been obtained. The development of the heart muscle cells is characterised by 2 processes. 1. Processes of synthesis and development - The ribosomes/polysomes which are to be found in great numbers are a characteristic of the synthesis of the myofilaments which plays an important role in the 1st phase of postnatal development. This synthesis of myofilaments takes place in the sarcoplasm by the formation of new individual myofilaments, in the interior and at the border of existing myofibrils, and at the level of the Z-lines. Mitochondria are developed in particular by the germination of small mitochondria the percentage of which amounts to about 16% at birth. The sarcoplasmic reticulum is developing in its longitudinal as well as transversal forms only during the 1st month. The disci intercalares, however, have been formed in the main already at birth. Cells are furthermore developing by mitotic processes during the first days. 2. Degradation processes - 2.1. The degradation is characterised by focal autophagocytotic processes in mitochondria concerning the cristae as well as the matrix and the outer membrane. During these processes autophagocytotic vacuoles are developing partly with myelin membranes. In addition, whole mitochondria are transformed into autophagocytotic vacuoles. Later on, mitochondria are also condensed and transformed into mitochondrial lipofuscin. 2.2. The autophagocytotic degradation of glycogen together with the sequestration and formation of vacuoles and myelin membranes are particularly striking. Lipofuscin, however, is to be observed in larger quantities only from the 4th month onwards. The investigations have shown that decisive phases of development can be determined: the day of birth, the 3rd, 4th, 5th, and 7th, and 14th day, as well as after the 1st, 3rd, and 6th month. This determination of the specific developmental phases of the heart muscle makes it possible to carry out investigations in a more economical and purposeful way.
为了描述心肌细胞的出生后发育和成熟过程，对雄性大鼠左心室肌组织在出生时、出生后第1、2、3、4、5、6、7、14和21天，以及出生后第1、2、3、4、5、6个月进行了电子显微镜研究。基于这些研究，获得了定量和定性数据。心肌细胞的发育具有两个过程。1. 合成与发育过程 - 大量存在的核糖体/多聚核糖体是肌丝合成的特征，这在出生后发育的第一阶段起着重要作用。这种肌丝的合成通过在肌浆中形成新的单个肌丝、在现有肌原纤维的内部和边界以及在Z线水平进行。线粒体特别是通过小线粒体的发芽而发育，其在出生时的百分比约为16%。肌浆网仅在第一个月以纵向和横向形式发育。然而，闰盘主要在出生时就已形成。细胞在最初几天还通过有丝分裂过程发育。2. 降解过程 - 2.1. 降解的特征是线粒体中与嵴、基质和外膜有关的局灶性自噬过程。在这些过程中，自噬泡部分带有髓鞘膜而形成。此外，整个线粒体转变为自噬泡。后来，线粒体也会浓缩并转变为线粒体脂褐素。2.2. 糖原的自噬降解以及液泡和髓鞘膜的隔离与形成尤为显著。然而，脂褐素仅从第4个月起大量出现。研究表明，可以确定发育的决定性阶段：出生日、第3、4、5、7和14天，以及出生后第1、3和6个月。确定心肌的特定发育阶段使得能够以更经济和有目的的方式进行研究。
