2009 Lecture 8

This lecture is an introduction to the development and functions of the placenta.

The placenta (Greek, plakuos = flat cake) named on the basis of this organs appearance. The placenta a mateno-fetal organ which begins developing at implantation of the blastocyst and is delivered with the fetus at birth. Only recently have we begun to understand the many different functions this organ carries out in addition to its role in embryonic nutrition. This lecture follows on the concepts of cardiovascular development covered in the previous lecture.

Lecture Objectives

Uterine and placental vasculature

Understanding of placental villi development
Understanding of placental structure
Understanding of placental functions
Brief understanding of placental abnormalities

UNSW Embryology Links

branched villi - or terminal villi, grow from sides of stem villi, region of main exchange, surrounded by maternal blood in intervillous spaces.

primary villi - week 2, first stage of chorionic villi development, trophoblastic shell cells (syncitiotrophoblasts and cytotrophoblasts) form finger-like extensions into maternal decidua.

secondary villi - week 3, second stage of chorionic villi development, extraembryonic mesoderm grows into villi, covers entire surface of chorionic sac

stem villi - or anchoring villi, cytotrophoblast cells attached to maternal tissue.

tertiary villi third stage of chorionic villi development, mesenchyme differentiates into blood vessels and cells, forms arteriocapillary network, fuse with placental vessels, developing in connecting stalk

References

Textbooks

The Developing Human: Clinically Oriented Embryology (8th Edition) by Keith L. Moore and T.V.N Persaud
Larsen’s Human Embryology by GC. Schoenwolf, SB. Bleyl, PR. Brauer and PH. Francis-West -

Additional Textbooks