Page 414 - Atlas of Histology with Functional Correlations

FIGURE 10.12 ■ Heart: a section of the left atrium, atrioventricular valve, and
left ventricle (longitudinal section). Stain: hematoxylin and eosin. Low
magnification.

FIGURE 10.13 | Heart: Right Ventricle,

Pulmonary Trunk, and Pulmonary Valve

(Longitudinal Section)

A section of the right ventricle and a lower portion of the pulmonary trunk (5)
are illustrated. As in other blood vessels, the pulmonary trunk (5) is lined by the
endothelium of the tunica intima (5a). The tunica media (5b) constitutes the
thickest portion of the wall of the pulmonary trunk (5); however, its thick, elastic

laminae are not seen at this magnification. The thin connective tissue tunica
adventitia (5c) merges with the surrounding subepicardial connective tissue
(2), with adipose tissue, coronary arterioles, and venules (3).

The pulmonary trunk (5) arises from the annulus fibrosus (8). One cusp of

its semilunar (pulmonary) valve (6) is illustrated. Similar to the AV valve (see
Fig. 10.12), the semilunar valve (6) of the pulmonary trunk (5) is covered with
endocardium (6). A connective tissue core (7) from the annulus fibrosus (8)
extends into the base of the semilunar valve (6) and forms its central core.

The thick myocardium (4) of the right ventricle is lined internally by the

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