Fimbriae (common pili) and flagella on the surface of bacterial cells. Left: dividing Shigella enclosed in fimbriae. The structures are probably involved in the bacterium's ability to adhere to the intestinal surface. Right: dividing pair of Salmonella displaying both its peritrichous flagella and its fimbriae.
Relaxin's peak is reached during the 14 weeks of the first trimester and at delivery. It is known to mediate the hemodynamic changes that occur during pregnancy, such as increased cardiac output, increased renal blood flow, and increased arterial compliance.
Pregnancy Contractions. A pregnancy contraction is when the uterus, the muscular organ where your baby grows, hardens and makes your entire abdomen feel as if it is tight or taut. In between contractions, the uterus will relax and everything in the abdomen will feel soft again.