The forebrain consists of lobes that translate input from the senses, and will be responsible for memory formation, thinking, reasoning, problem solving. The midbrain will serve as a relay station, coordinating messages to their final destination. The hindbrain will be responsible for regulating the heart, breathing and muscle movements. Thyroid continues to develop and the lymphatic system, which filters out bacteria, starts to form. Otic placode invaginates and forms the otic vesicle, which will develop into the structures needed for hearing and maintenance of equilibrium.
Retinal disc presses outward and touches the surface ectoderm.
In response the ectoderm proliferates forming the lens disc. Specific parts of the eye, such as the retina, the future pigment of the retina and the optic stalk are identifiable. Primitive mouth with a tongue is recognizable. Thyroid continues to develop and the lymphatic system, which filters out bacteria, starts to form. Thorax Heart chambers are filled with plasma and blood cells making the heart seem distended and prominent.