The development and morphology of the incisive fissure and the transverse palatine suture in the human fetal palate.

The incisive fissure and the transverse palatine suture are well known anatomical structures in the human palate. The purpose of the present study was to describe the development and the morphology of the incisive fissure and the transverse palatine suture. Another purpose was to compare the nature of both structures with the aim of elucidating their possible function in the developing facial skeleton. Descriptions of the initial formation, development, and maturation of the incisive fissure and the transverse palatine suture, in combination with a comparison between the suture systems, were not found in the literature. Human fetal material, consisting of a total number of 96 specimens with gestational ages ranging from 9 to 24 weeks, was analyzed macroscopically (radiologically and after devisceration) and microscopically (histologically). The bony maturation of specimens was recorded by relating to the stages of maxillary ossification (MAX), an index for skeletal maturity of the palate. The study revealed pronounced macroscopic and microscopic differences between the incisive fissure and the transverse palatine suture. The transverse palatine suture appears to be a site for anteroposterior growth of the palate. The incisive fissure has a different macroscopic and microscopic appearance and presumably has a function more closely related to the development of the dentition and the anterior part of the maxilla.