PRACTICAL COURSE IN HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 3. GENERAL EMBRYOLOGY. HUMAN EMBRYOLOGY.

Slide 21. Placenta (maternal part).

Staining: hematoxylin and eosin.

Magnification: x80.

The maternal part of the Placenta is formed by the uterine mucosa at the site where chorionic villi invade it. This is the decidua basalis. It is represented by the basal plate (1)—Connective Tissue rich in large, pale decidual Cells (2). From the basal plate, projections extend deep into the placenta, forming incomplete septa. These septa divide the placenta into Blood-filled chambers known as lacunae (3). Chorionic villi are located within the lacunae. A villus consists of a stem and numerous branches (4), which may be cut in cross, oblique, or longitudinal section; they appear round or oval in shape and are bathed in blood. The core of the villus is composed of embryonic Connective tissue with a network of Blood Vessels of varying diameters. The surface of the villi is covered by trophoblast (5). Nutrients and oxygen from the maternal blood diffuse into the fetal blood through the layers of the trophoblast, the connective tissue of the villi, and the endothelium of the fetal vessels located within the villi. This constitutes the placental barrier. The basal plate is covered by an amorphous substance known as Rohrs fibrinoid (6).

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Slide 21. Placenta (maternal part).



Last update: 07/08/2026

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