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.
Embryology is the branch of developmental biology that studies the beginning and early growth of sexually reproducing organisms. This life science specialty focuses primarily on embryogenesis (the formation and development of embryos). In humans, the term embryo is traditionally reserved for the first two months of development. After that point, the term âembryoâ is replaced by the term âfetus,â which then applies until birth. At the beginning of the individualâs development, the entity is a single cell. After two months, it has limbs, distinct fingers and toes, internal development, and countless cells.