And these germ layers include the ectoderm, the endoderm and the mesoderm. Now, as we'll see in just a moment, the cells of each one of these these germ layers eventually give rise to specific organs and structures and systems found within the adult human individual. So let's begin by briefly discussing which structures in which organs and systems are formed by each one of these three germ layers. And let's begin with the ectoderm. Now, the ectoderm is the outer layer. It's the external layer of that developing embryo, as we'll see in just a moment.