Final answer:
Totipotent embryonic cells can develop into complete organisms, but as they differentiate into pluripotent and then multipotent cells, they lose this ability and instead contribute to forming specific tissues and organs through the three germ layers.
Step-by-step explanation:
The early embryonic cells referred to in the student's question are known as totipotent stem cells. These cells have the remarkable ability to differentiate into any cell type required for the development of an organism. Initially, upon fertilization, the zygote commences rapid mitotic divisions, leading to the formation of an embryo. It is during these initial stages that totipotency is exhibited, with each cell having the capability to give rise to a complete organism.
Following totipotency, cells become pluripotent, meaning they can differentiate into any cell type within the human body but are no longer capable of developing into a full organism. These pluripotent cells then give rise to the three germ layers: ectoderm, mesoderm, and endoderm, which eventually form all the tissues and organs.
The germ layers each contribute to different tissue types: the ectoderm leads to nervous tissue and skin cells, mesoderm to muscle cells and connective tissue, and endoderm to inner organ linings. Differentiation is a crucial part of this process, where cells express specific genes to become the diverse cell types necessary for forming functional tissues and organs.