[Developmental studies on the palatine bone in the human skull. With special references to the development of its...

For the purpose of these studies 83 cases of fetus skulls and 4 cases of adult skulls were used and the following results were obtained; The palatine bone was found to ossify in a fetus between the middle of the second month and that of the third month. The pyramidal process and conchal crest were first observed in a 9.0 cm fetus. The orbital process, sphenoidal process, sphenopalatine notch and nasal crest were first found in a 16.0 cm fetus. The ethmoidal crest was first found in a 20.0 cm fetus. The posterior nasal spine was first found in a 33.0 cm fetus. The anterior part of the palatal surface of the horizontal plate was found to cover the posterior part of the nasal surface of the palatine process of the maxilla so as to form two layers one above the other. However, the covered surface gradually reduced in size finally to make the transverse palatine suture between the maxilla and the palatine bone in the adult. The transverse length of the horizontal plate was almost equal to its antero-posterior length up until the fifth month fetus, while the former was constantly longer than the latter in the fetus older than the sixth month. The perpendicular plate was constantly longer than the horizontal plate in the fetus older than the fourth month. The metrical comparison between the fetus and the adult revealed that the most well-developing part of the palate bone was the height of the perpendicular plate, which developed 10.9 times longer than that of the fourth month fetus. The rest of the part developed 4.5-5.5 times longer than that of the fourth month fetus.