Maxillary ossification in a series of six human embryos and fetuses aged from 9 to 12 weeks of amenorrhea: clinical implications

Embryonic Development of the Orbit

The embryonic and fetal development of the orbit comprises a series of sequential events, starting with the fertilization of the ovum and extending until birth. Most of the publications dealing with orbital morphogenesis describe the sequential development of each germinal layer, the ectoderm with its neuroectoderm derivative and the mesoderm. This approach provides a clear understanding of the mode of development of each layer but does not give the reader a general picture of the structure of the orbit within any specified time frame. In order to enhance our understanding of the developmental anatomy of the orbit, the authors have summarized the recent developments in orbital morphogenesis, a temporally precise and morphogenetically intricate process. Understanding this multidimensional process of development in prenatal life, identifying and linking signaling cascades, as well as the regulatory genes linked to existing diseases, may pave the way for advanced molecular diagnostic testing, developing minimally invasive interventions, and the use of progenitor/stem cell and even regenerative therapy.

Incidence and morphology of the incisive suture in CT scanning of young children and human fetuses

PURPOSE

Incisive suture is a suture classically described on the oral face of the palate in fetuses and young children. The aim of our study was to describe the evolution of the incisive suture in human fetuses and to evaluate the incidence of this suture in a population of young children under 4 years, to determine if there is a possibility of improving the anterior growth of the maxilla, by stimulation of this suture.

METHODS

One hundred and thirty CT scan images of patients aged from birth to 48 months have been studied and nine fetal palates aged from 18 to 26 weeks of development, have been scanned using high-resolution X-ray micro-computed tomography RESULTS: The CT scan images of patients showed that an incisive suture was present in 33/130 cases (25,4%). All the patients with a suture were under 2 years old. The fetal palate study showed that the suture was present in the inferior aspect of the palate (oral cavity) in all cases. The incisive suture increased from 18 to 24 weeks. At 26 weeks it stopped growing although the intercanine length increased. Considering the closure of the suture in a vertical plane, our study on fetuses has shown that the incisive suture is closing from its superior side (nasal side) to its inferior side.

CONCLUSIONS

Considering all these results it appears to us that the incisive suture is partially ossified after birth, it cannot be stimulated by orthodontic appliances.

Embryologic and Fetal Development of the Human Orbit

PURPOSE

To review the recent data about orbital development and sort out the controversies from the very early stages during embryonic life till final maturation of the orbit late in fetal life, and to appreciate the morphogenesis of all the definitive structures in the orbit in a methodical and timely fashion.

METHODS

The authors extensively review major studies detailing every aspect of human embryologic and fetal orbital morphogenesis including the development of extraocular muscles, orbital fat, vessels, nerves, and the supportive connective tissue framework as well as bone. These interdisciplinary studies span almost a century and a half, and include some significant controversial opposing points of view which the authors hopefully sort out. The authors also highlight a few of the most noteworthy molecular biologic studies regarding the multiple and interacting signaling pathways involved in regulating normal orbital morphogenesis.

RESULTS

Orbital morphogenesis involves a successive series of subtle yet tightly regulated morphogenetic events that could only be explained through the chronological narrative used by the authors. The processes that trigger and contribute to the formation of the orbits are complex and seem to be intricately regulated by multifaceted interactions and bidirectional cross-talk between a multitude of cellular building raw materials including the developing optic vesicles, neuroectoderm, cranial neural crest cells and mesoderm.

CONCLUSIONS

Development of the orbit is a collective enterprise necessitating interactions between, as well as contributions from different cell populations both within and beyond the realm of the orbit. A basic understanding of the processes underlying orbital ontogenesis is a crucial first step toward establishing a genetic basis or an embryologic link with orbital disease.

Anatomical modifications of the mid palatal suture during ageing: a radiographic study

In transverse maxillary deficiencies it is important to know if the mid palatal suture is obliterated or not, to decide which treatment to perform (orthodontic expansion or surgical disjunction of the suture). The maxillary sutures obliteration has been used in forensic medicine in estimating adult age at death. In order to determine the proportion of mid palatal suture obliteration in the elderly in man, we examined 100 consecutive CT scans of the palate. This study has shown that the age of mid palatal total obliteration was variable. The obliteration begins in the anterior and in the superior part of the palate. The inferior part of the junction between the palatal processes is the last part of the suture to be obliterated.

Incisive suture (fissure) in the human fetus: radiographic and histologic study

OBJECTIVE

An anatomic study, in man, of the structure commonly known as the incisive suture (sutura incisiva) or incisive fissure has been performed to determine whether this structure belongs to the morphofunctional concept of a facial suture.

MATERIAL

Eighteen palates of human fetuses of 9 weeks to 29 weeks after conception.

METHOD

Anatomic, radiographic examination of the palate. Histologic study of sagittal and parasagittal sections of the palates (3 mm each).

RESULTS

The histologic aspect is that of a facial suture, with very poor vascularization. This suture is partial, limited laterally by osseous trabeculae.

CONCLUSIONS

This particular suture, whose function in growth of the palatal process of the maxilla is discussed, could represent the phylogenetic vestige of the incisive-maxillary suture present in all nonhuman mammals.