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.
The First Few Weeks and Pregnancy Cramping and Cramps. One of the first changes to occur in the female body in preparation for the new baby is the release of additional female hormones like estrogen and progesterone. These hormones tell the uterus to expand, among other messages to the female body.