Before the fertilized ovum
reaches the uterus
, the mucous membrane
of the body of the uterus undergoes important changes and is then known as the decidua
. The thickness and vascularity of the mucous membrane are greatly increased; its glands are elongated and open on its free surface by funnel-shaped orifices
, while their deeper portions are tortuous
and dilated into irregular spaces. The interglandular tissue is also increased in quantity, and is crowded with large round, oval, or polygonal cells, termed decidual cells
- - "Female Reproductive System: placenta, decidual cells"