The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound.
Tympanic cavity. Facial canal. Internal carotid artery.
Auditory ossicles. Tympanic cavity. Deep dissection.
Human embryonic development
Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form the single cell zygote and the germinal stage of development commences. Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus.
The eight weeks have 23 stages.
Eight-cell embryo, at three days
Histogenesis of the three germ layers
Embryo attached to placenta in amniotic cavity
Nine-week-old human embryo from an ectopic pregnancy