Medically reviewed by Renita White, MD Several gynecologic conditions cause uterus problems. Some cause no symptoms, while others cause mild to severe problems ranging from irregular or heavy bleeding ...

After implantation, the trophectoderm starts reshaping the endometrium. A layer of cytotrophoblasts—trophoblast progenitor cells—emerges around the same time as the invading primitive syncytium. By 12 ...