title: Maxillary ossification in a series of six human embryos and fetuses aged from 9 to 12 weeks of amenorrhea: clinical implications.
abstract: An anatomic controversy exists concerning the number of nuclei of ossification of the maxilla in human embryos and fetuses. Many authors have described two maxillary ossification nuclei, an incisor nucleus and a maxillary nucleus properly so-called. Some of these have explained congenital labiomaxillary clefts by a defect of bony fusion between these two ossification nuclei. Others consider that there is only a single nucleus for maxillary ossification. In order to settle this question we performed a histologic study in six heads of embryos and fetuses aged from 9 to 12 weeks of amenorrhea (WA) to demonstrate the presence of one or more sites of maxillary ossification at the earliest stages. Our study revealed, on each side, a single zone of maxillary ossification, present from 9 WA, in the form of a sheet of osteoid tissue situated in close contact with the dental lamina. Maxillary ossification then progressed in the lateromedial direction, preserving a median transverse and ventral mesenchymal septum. This septum may constitute the phylogenetic remnant of an ancestral premaxilla.
authors.affiliation: Faculté de Médecine Xavier-Bichat, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Vacher
authors.forename: H
authors.initials: H
authors.lastname: Copin
authors.forename: M
authors.initials: M
authors.lastname: Sakka
mesh_terms: D000568:Amenorrhea; D002102:Cadaver; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D008334:Mandible / Q000033:anatomy & histology / Q000196:embryology*; D008437:Maxilla / Q000033:anatomy & histology* / Q000196:embryology*; D010012:Osteogenesis / Q000502:physiology*; D010159:Palate / Q000033:anatomy & histology / Q000196:embryology*