So what else do we form? Well, the thyroid gland, the parathyroid gland and the thiamus gland. All these glands are essentially formed by the endoderm germ layer. Now, the lungs, and more specifically the epithelial layer of the lungs is also formed from the endoderm as well as the epithelial of our reproductive ducts, our reproductive system, our urethra and our bladder. So to summarize, our ectoderm basically forms the outer portion of the skin as well as some organs found inside of our body. And that takes place because a lot of these ectodermal cells actually invaginate and end up inside that developing embryo.