Vatican City is home to some of the most famous art in the world. St. Peter's Basilica, whose successive architects include Bramante, Michelangelo, Giacomo della Porta, Maderno and Bernini, is a renowned work of Renaissance architecture.
This is when the baby's brain, spinal cord, heart and other organs begin to form. The embryo is now made of three layers. The top layer â the ectoderm â will give rise to your baby's outermost layer of skin, central and peripheral nervous systems, eyes, inner ears, and many connective tissues. Your baby's heart and a primitive circulatory system will form in the middle layer of cells â the mesoderm.
The human nervous system starts to form very early in the embryoâs development. At the end of the gastrulation phase, an elongated structure, the notochord, is laid down. The embryo thereby changes from a circular organization to an axial oneâa critical step in the development of its nervous system.ext, the zygote divides into 2 cells, then 4, then 8, then 16, and so on, until a spherical mass of cells has formed. This first stage of development is often called segmentation. Gradually, a cavity develops at the centre of this ball as it exits the fallopian tube to implant itself in the wall of the uterus.