Function of the Placenta

Developmental and Physiologic Anatomy of the Placenta

While the trophoblastic cords from the blastocyst are attaching to the uterus, blood capillaries grow into the cords from the vascular system of the newly forming embryo. By the 16th day after fertilization, blood also begins to be pumped by the heart of the embryo itself. Simultaneously, blood sinuses supplied with blood from the mother develop around the outsides of the tro-phoblastic cords. The trophoblast cells send out more and more projections, which become placental villi into

Figure 82-4

Implantation of the early human embryo, showing trophoblastic digestion and invasion of the endometrium. (Courtesy Dr. Arthur Hertig.)

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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