By the upgrowth of the surrounding parts the olfactory areas are converted into pits, the nasal pits or olfactory pits, which indent the fronto-nasal process and divide it into a medial and two lateral nasal processes.
Head end of human embryo of about thirty to thirty-one days.
Same embryo as shown in Fig. 45, with front wall of pharynx removed.
The roof of the mouth of a human embryo, aged about two and a half months, showing the mode of formation of the palate.
The head and neck of a human embryo thirty-two days old, seen from the ventral surface.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)