Development of the face.

ABSTRACT

The human face develops between the fourth and eighth week after conception. Its development can be traced to five facial primordia appearing around the stomodeum in the fourth week. They are, namely, one frontonasal prominence, two maxillary and two mandibular prominences. Two nasal placodes develop on each side of the lower part of the frontonasal prominence at the end of the fourth week and further develop into the medial and lateral nasal prominences. The early development of the human face is similar to that of other mammals, such as pigs, rats and rabbits; all of which acquire branchial arches in the early stage of development. The rabbit branchial arches develop at the 4-5 mm stage and nearly disappear at the 12-14 mm stage, as the second one grows dorsally and obliterates the cervical sinus. The medial and lateral nasal prominences appear at the 4-5 mm stage. At the 12-14 mm stage the nasal cavities are more extensive than those of a 10 mm pig embryo and are of the same stage of development as a 15 mm pig embryo. Currently, we use 10 and 15 mm pig embryos as models in this study of human facial development. However, in the future, it will be more suitable to use 4-12 mm rabbit embryos because they are obtained more easily.