Wednesday, 7 November 2012

Which of the following is in direct contact with maternal blood in lacunae of the placenta?

a. Cells of the cytotrophoblast
b. Extraembryonic mesoderm
c. Fetal blood vessels
d. Cells of the syncytiotrophoblast
e. Amniotic cells

The answer is d. In the developing fetus, the maternal blood is in direct contact with the syncytiotrophoblast. During implantation, the syncytiotrophoblast invades the endometrium and erodes the maternal blood vessels. Maternal blood and nutrient glandular secretions fill the lacunae and bathe the projections of syncytiotrophoblast. Primary villi consist of syncytiotrophoblast with a core of cytotrophoblast cells. In secondary villi, the cytotrophoblast core is invaded by mesoderm and subsequently by umbilical blood vessels in tertiary villi.


1 comment:

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