👉 Protolithic is a scientific concept in developmental biology that describes the development of cells and tissues within an organism, from a single cell or organ to a larger tissue or whole organism. Protolines are often associated with specific developmental stages such as early embryogenesis or gastrulation. They can be divided into two main types: mesoderm protolines (cells in the early embryo that form the neural tube) and endoderm protolines (cells that form the skin, bones, muscles,
