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Objective: To determine the anatomy of the soft and hard palate during fetal growth in order to improve its ultrasonographic prenatal visualization., Design: Anatomic study in human formalin-fixed fetus., Methods: The heads of 18 second and third trimester fetuses were studied in the median sagittal plan. Measurements of the soft palate, the velopharynx, the root of the tongue, and the oral floor were taken. The hard palate/soft palate angle and the anterior cranial base/soft palate angle were measured., Results: The growth of the hard palate was linear, and the growth of the soft palate was polynomial (second order) during the period studied. The hard palate/soft palate angle was 150.33 degrees +/- 7.62 and 150.20 degrees +/- 6.67 in the second and third trimester, respectively. The anterior position of the soft palate in relation to the anterior cranial base was 48.8 degrees +/- 3.13 in the second trimester and 52.26 degrees +/- 3.31 in the third trimester. Its posterior position was 89.66 degrees +/- 5.51 in the second trimester and 92.97 degrees +/- 4.01 in the third trimester. Throughout the fetal period, the soft palate moved downward relative to the clivus and cervical spine., Conclusions: Despite the nonlinear growth and downward displacement of the soft palate during fetal life, its position remains stable. These results may be useful to explore the fetal soft palate using 2D and 3D ultrasonography and to improve the prenatal diagnosis of isolated cleft palate.

Objective: To propose a new method, which allows for a complete description of primary and secondary cleft palates, incorporating elements that are related to the palate, lip, and nose that will also reflect the complexity of this problem., Method: To describe the type of cleft, two embryonic structures were considered: (1) the primary palate, formed by the prolabium, premaxilla, and columella and (2) the secondary palate, which begins at the incisive foramen and is formed by a horizontal portion of the maxilla, the horizontal portion of the palatine bones, and the soft palate. Anatomical characteristics to be considered were defined, and a new method is proposed to more fully describe any cleft., Results: A description of five cases was made using the method proposed in this work and compared with other published methods for the classification and description of clefts., Conclusions: A mathematical expression was developed to characterize clefts of the primary palate, including the magnitude of palatal segment separation and the added complexity of bilateral clefts, yielding a numerical score that reflects overall complexity of the cleft. Clefts of the secondary palate are also considered in a separate score. Using this method, it is possible to incorporate elements that are not considered in other approaches and to describe all possible clefts that may exist.

Objective: The purpose of this study was to investigate, in a normal human fetal sample, the development of the anterior area of the palate. Emphasis has been placed on the bilateral epithelial fusion lines between the soft-tissue palatal shelves and the premaxillary mucosa, and on the relationship between these fusion lines and the locations of the inclusive fissures and of the tooth buds. The goal was to evaluate how the location of clefts in cleft lip and palate (CLP) patients interferes with tooth buds that are often affected in clefting., Design: Nineteen maxillas of human fetuses underwent histologic examination after serial horizontal sectioning. Superimpositions of tracings from photographs of the histologic sections yielded information on the maxillary morphology at different levels., Results: After elevation and fusion of the soft-tissue palatal shelves, the palatal fusions were Y-shaped. During subsequent osseous palate development, including formation of the incisive fissure and intermaxillary suture, the Y-shaped epithelial fusions disintegrated. The locations of the anterior arms of the epithelial Y and of the incisive fissure did not coincide., Conclusions: The incisive fissure is likely not the location of clefts in CLP. The location of anterior palatal clefting in CLP patients follows the original course of the epithelial fusion between the palatal shelves and the premaxillary mucosa found in the region of the lateral incisors.

The two specific aims of this study were as follows: to evaluate the appropriateness of the A/Jax mouse model in the investigation of the key cellular stages in prenatal soft palate morphogenesis and myogenesis; and to describe structural differences in the histomorphology of the soft palate anatomy from cleft and noncleft mice prior to, during, and after palatogenesis. Cleft-induced and control groups of A/Jax mouse embryos from timed pregnancies were harvested sequentially on gestational days 15 to 19. Embryos were weighed and staged for external body morphology. The heads were removed and fixed for light microscopy, sectioned serially in the frontal plane at 10 microns and stained with hematoxylin-eosin to characterize and compare the soft palate musculature. All observations were made at the head depth of the trigeminal ganglion in both age- and stage-matched embryos. The following findings were made: (1) the A/Jax mouse is a suitable animal model for the study of soft palate myogenesis; (2) there were no discernible morphologic differences between the soft palate muscles in cleft and noncleft A/Jax mice when viewed under light microscopy; (3) the soft palate and related muscles were identifiable as muscle fields, in both the cleft and noncleft fetuses, as early as gestational day 15 and as specific muscles at gestational day 18; (4) in both the cleft and noncleft A/Jax fetuses, the soft palate muscles appeared in a sequential anatomic fashion (the palatine aponeurosis appeared first, next the tensor palatini, and then the levator palatini muscles); and (5) in the cleft palate fetuses, both pterygoid plates were angulated and displaced laterally.

To test the hypothesis that soft palate muscles are abnormal in cleft palate, we compared soft palate morphogenesis in fetuses with cleft palate (n = 4) to age-matched (n = 3) and nonmatched (n = 1) control specimens. The morphologic status of all soft palate and masticatory structures were classified into one of six stages based on the level of histogenesis. At 54 mm crown-rump length (CRL), the levator veli palatini (L), palatopharyngeus (PP), and palatoglossus (PG) in cleft subjects demonstrated mesenchymal condensation into myoblastic fields, lagging behind the control specimens (97 mm CRL), which displayed definitive fields of myoblasts and myotube formation. In the 175 mm and 225 mm cleft and the 170 mm and 192 mm control specimens, muscular morphology was similar and had reached its postnatal appearance for the tensor veli palatini (175 m only) and L, PP, PG (225 mm only). Muscle fiber directions were, however, disoriented and disorganized, especially close to the medial epithelial edge of the cleft. The levator veli palatini, could not be distinguished as a discrete muscle in the cleft specimens, and what we believed to be the PP and PG seemed "normal" at the level of light microscopy, but malpositioned in a superior direction. This preliminary study demonstrates for the first time that early myogenesis in cleft palates differs from normal.

Surgical correction of clefts of the soft palate leads to varying degrees of normal function although the repair itself is successful. Explanations for this include structural abnormalities of the muscles. Previous studies have focused primarily on gross anatomical features of late fetal and postnatal cleft palate musculature; however, infrequent reference has been made to early prenatal morphologic patterns of soft-palate development, beginning with the embryo. Thus we evaluated the chronology of prenatal myogenesis of the soft palate from its early mesenchymal phase through the appearance of definitive palatal muscles and associated structures in a sample of 22 human fetuses that represented postfertilization weeks 6.5 to 20.5 (18- to 192-mm crown-rump length). Specimens were histologically prepared for descriptive and morphometric light microscopy. Data were collected on the earliest appearance times of identifiable soft palate and associated structures within the mesenchymal field and on their individual stages of myogenesis (e.g., for muscles, from mesenchyme to myoblasts to fascicles). Analyses showed that (1) palatal muscles and related bony structures emerge sequentially as densely staining mesenchymal subfields within the larger mesenchymal soft-palate field during the 6- to 9-week period, with the tensor veli palatini muscle appearing earliest, and the musculus uvulae latest; (2) further morphogenesis of the soft palate and associated structures follows a definite timeline; and (3) by 16 to 17 weeks the postnatal palatal morphology is in place.

A new method of anatomic dissection and image reconstruction using computer techniques for better understanding of eustachian tube (ET) functioning is presented. Coronal sections of two noncleft fetal skulls were photographed and projected on a graphic tablet. Contours of the pertinent structures were digitized using a mouse. Coordinates of all digitized points were entered into a special computer program. The data were transformed into three-dimensional representations of anatomic structures. The levator veli palatini muscle (M-LVP) was found to have a close relationship with the ET running underneath it and passing at the inside of the pharyngeal edge of the medial cartilage before entering the soft palate. On M-LVP contraction, this part of the medial ET cartilage appears to be the sole point of impact for ET opening. The tensor veli palatini muscle (M-TVP) is connected with the lateral cartilage of the ET and leaves the ET, rounding the pterygoid hamulus before entering the palatal aponeurosis. On this anatomic basis, action of the muscle by isotonic contraction appears to be more likely than isometric contraction.

Some clefts of the lip and palate appear to result from the rupture after fusion has occurred. This possibility is suggested by (1) epithelial remnants found in the palatal shelves, (2) regenerating epithelium found in the palatal clefts of human fetuses older than 13 weeks, (3) immature epithelium visible on the margin of the cleft, (4) nasopalatine ducts cut off by clefts, (5) perforation type cleft found in the hard palate, (6) a Simonart band visible in six cleft mouse fetuses, (7) duplicated upper lateral incisors enclosing a lip-jaw cleft, and (8) rodent cavities in the lip or palate related to cleft formation.