Question

Which set of structures is ectodermal in origin?

• A. Brain, liver, gills
• B. Spinal cord, heart, epidermis
• C. Epidermis, brain, retina
• D. Dermis, lung, nerves

Answer 1

The correct option is C Epidermis, brain, retina

In animals as development progresses from zygote to embryo, three concentric layers, called germ layers, form the various tissues and organs of the body. Ectoderm, the germ layer covering the surface of the embryo, gives rise to the outer covering of the animal and, in some phyla, to the central nervous system. Thus structures like epidermis, brain and retinal layer of eye are ectodermal in origin. Endoderm, the innermost germ layer, lines the developing digestive tube, or archenteron, and gives rise to the lining of the digestive tract (or cavity) and organs such as the liver and lungs of vertebrates. Animals that have only these two germ layers are said to be diploblastic. Diploblasts include the animals called cnidarians (jellies and corals, for example) as well as the comb jellies. All bilaterally symmetrical animals have a third germ layer, called the mesoderm, between the ectoderm and endoderm. Thus, animals with bilateral symmetry are also said to be triploblastic (having three germ layers).