. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 106 M. G. MARTYNOVA AND O. A. BYSTROVA pc. Figure 1. Light micrograph of semithin section through the atrium of the snail Ac/uitina fit/ica. The heart wall consists of epicardium (arrows) facing the pericardia! cavity (pc) and a myocardium (m). The endoihdial cells (arrowheads) adjoin the luminal surface of the myocardial trabeculae hi. heart lumen. Scale bar = mm. somes, and a number of small vesicles. UCs were easy to distinguish from other nonmuscle cells in the heart, such as endothelial cells, gliointerstitial cell
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 106 M. G. MARTYNOVA AND O. A. BYSTROVA pc. Figure 1. Light micrograph of semithin section through the atrium of the snail Ac/uitina fit/ica. The heart wall consists of epicardium (arrows) facing the pericardia! cavity (pc) and a myocardium (m). The endoihdial cells (arrowheads) adjoin the luminal surface of the myocardial trabeculae hi. heart lumen. Scale bar = mm. somes, and a number of small vesicles. UCs were easy to distinguish from other nonmuscle cells in the heart, such as endothelial cells, gliointerstitial cells accompanying nerve fibers, and blood cells, by this extreme paucity of cytoplas- mic organelles and the presence of a spherical "empty" nucleus whose chromatin is not dispersed but clumped immediately beneath the nuclear envelope. These peculiar nuclei were commonly surrounded by fragments of evi- dently destroyed cytoplasm, which may presumably result from occasional damage of UCs during fixation. A high fragility of UCs probably accounts for the fact that these were missed in many earlier relevant publications on the ultrastructure of the molluscan heart. Sometimes small muscle cells were seen containing only a few myofilaments randomly arranged and embedded into some amorphous material (Fig. 5). Moderately differenti- ated myocytes were also seen (Figs. 6, 7). Thus, all mor- phological intermediate stages may be observed in the mol- luscan heart—from small oval cells with no or only a few myofilaments to well-differentiated cardiomyocytes—and a series of cells representing the process of transformation of undifferentiated cell into mature muscle cell can be identi- fied. We failed to observe any mitotic figures in UCs or myocytes. Ploitly analysis Cytophotometric measurements of DNA contents in KOH-dissociated, Feulgen-stained cells showed that both atrial and ventricular myocytes of the snail heart are exclu- sively mononucleated, with the nuclei being diplo
Size: 1334px × 1873px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
