[Trabeculae of the sinus part of the heart interventricular septum in the fetal period of human development].

In the series of 91 samples of human heart obtained from fetuses at develo pmental weeks 17-28 and formed without major defects and minor anomalies, the relief of the sinus part (SP) of the interventricular septum (IVS) was studied on the side of right ventricle (RV). Myocardial trabeculae carneae (MTC) were found in SP in 96.7% of the cases. MTC, associated with the IVS myocardium along their entire length (parietal MTC). were twice as frequent as bridge-like MTC. MTC were predominantly concentrated at the posterior corner of the RV; these were e xclusively bridge-like MTC. Most frequently, MTC were absent near the IVS membranous region. An individual anatomical variability of the relief of the RV in the fetal heart was demonstrated. Depending on the number, anatomical type and mutual position of the MIC, three variants of the SP relief were distinguished: hypertrabecular, hypotrabecular and intermediate. From week 17 to week 28 of the intrauterine life, the hearts of the fetuses may differ in the form of MTC, however their number and the anatomical type within a particular variant of the SP remained constant The existence of the parietal longitudinal MTC on the right side of the IVS SP is proposed to be one of the hallmarks of the anatomically "normal" (ordinarily formed) heart in the human fetuses.

[Left-ventricular surface trabeculae of the interventricular septum in the human fetal heart].

Left-ventricular surface of the interventricular septum (IVS) was studied in the heart of 85 human fetuses (at weeks 17-28 of development) formed without congenital defects and minor abnormalities. Two anatomical types of trabeculae (bridge-like and parietal) and their two topographical groups are described: trabeculae of the anterior corner of the left ventricle (LV) and the septal trabeculae. The prevalence of trabeculae in both groups was found to be equal (81-81.2%). No correlation between the numbers of septal trabeculae and the trabeculae of the anterior LV corner was found. While the parietal trabeculae were detected in both groups, the bridge-like type was found only in the anterior LV corner. The number of the bridge-like trabeculae of the anterior LV corner and the septal trabeculae increased from the base to the apex of the heart; this was accompanied by the decrease in the IVS myocardium compactness. Among the first topographical group, there were trabeculae in the shape of skewed cylinders or truncated cones, flattened perpendicularly to their long axis. As a rule, in cone-shaped trabeculae, their broad base was directed towards the IVS. In the second group, the ribbon-shaped trabeculae were prevalent. The data on trabecular width are presented. The formation of the cardiac LV and IVS trabecular pattern in prenatal period is discussed.

[Trabeculae and intertrabecular spaces of the heart interventricular septum: anatomical structure and development].

The review presents traditional and new concepts on the development of the trabeculae carneae and intertrabecular spaces (ITS) in the heart ventricles. Myocardial trabeculation preceeds the ventricular septation and at the same time underlies the formation of the interventricular septum. Trabeculae carneae seem to generate the contractile force of the embryonic myocardium. The differences between right and left ventricular trabecular patterns are conditioned by the changes of intracardiac blood flow during the prenatal period. Anatomical characteristics of the right inlet and outlet relief are reviewed. Special emphasis is given to the correlations of the terms "septomarginal trabeculation" and "moderator band". It is noticed that ITS anatomy is still insufficiently studied. The necessity to develop the anatomical criteria of normal intracardiac structures is accentuated.