WORKSHOP IN HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 5. SPECIAL HISTOLOGY

Cardiovascular System

Slide 80. Wall of the bovine heart.

Staining: hematoxylin and eosin.

Magnification: x400.

Under low magnification, identify the layers of The Heart wall. The endocardium (1) appears as a pinkish band lined with endothelium featuring prominent purple nuclei (2). Beneath it lies the subendothelial layer (3) consisting of loose Connective Tissue, followed deeper by the myoelastic (4) and external connective tissue (5) layers (subendothelial stratum).

The myocardium (6) forms the bulk of the heart. Within the myocardium, observe bundles of cardiomyocytes with centrally located nuclei (7). Anastomoses (8) can be seen between these cardiomyocyte chains. Inside the bundles—which function as muscular "fibers"—the cardiomyocytes are joined by intercalated discs (9). Cardiomyocytes exhibit cross-striations due to the presence of isotropic (light) and anisotropic (dark) discs within the myofibrils. Clear spaces filled with loose Fibrous connective tissue are visible between the chains of cardiomyocytes.

Clusters of conducting (atypical) cardiomyocytes lie directly beneath the endocardium. In cross-section, they appear as large pink Cells (10) featuring nuclei larger than those of working cardiomyocytes and a sarcoplasm that predominates over myofibrils.

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Slide 80. Wall of the bovine heart.



Last update: 07/08/2026

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