eight of your pregnancy your baby’s cells multiply rapidly and they begin to perform specific functions. This process of specialization is called differentiation. It’s necessary to produce all the different cells that make up a human being. As a result of differentiation, your baby’s main external features also will begin to take shape. No longer just a mass of cells, your baby - now officially called an embryo - is starting to take on a distinct form. This article has moved to an other website of ours, namely babyboyandgirlnames.com. Read the full article about 5 weeks pregnany there.