Myoneural maturation and function of the foetal rat tongue at the time of secondary palate closure

Wragg, Laurence E.; Smith, Jacob; Borden, Charles S.

doi:10.1016/0003-9969(72)90193-8

Cited by 43 publications

(22 citation statements)

References 13 publications

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“…1979;Coleman, 1965;Walker and Ross, 1972], In fact, the palatal shelf rotates to a certain extent by a flip-up movement, implying the existence of intrinsic tensile forces within the palatal tissue [Walker and Fraser, 1956] in a dorso-medial direc tion at the critical period of elevation. In the present experiment, this was observed under a dissecting micro scope by withdrawing the intervening tongue downward by a forceps, as reported previously by several workers [Walker and Fraser, 1956;Walker and Ross, 1972;Ferguson, 1978], There are some suggestions [Greene and Pratt, 1976;Wragg et al, 1972] that the tongue has the capacity of voluntary movement for palatal shelf rotation. How ever, it was necessary to open the mouth and to with draw the tongue to a considerable extent for the shelf rotation in the live fetus in our experiment mentioned above.…”

Section: Discussionsupporting

confidence: 52%

The Anterior Half of Mouse Palatal Shelf Is Elevated by a Remodeling Movement

Yasuda¹,

Fujimoto²

1986

Cells Tissues Organs

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During the development of the mammalian secondary palate, the lateral palatine process (the palatal shelf) rises from the vertical plane beside the tongue to the horizontal plane above it. To determine the mode of elevation of the palatal shelf, we have cultured the whole ICR mouse fetus on day 14 (0–2 h) of gestation with a scratch as a marker at the distal edge of the anterior fourth of the vertical palatal shelf. After 6–18 h of culture, the survival ratio was 78.9% and the palatal shelf rose horizontally above the tongue in 22.2% of the surviving fetuses. The scratch was found as a scar on the oral epithelium laterally to the medial edge of the elevated palatal shelf. These results indicate that the medial edge of the horizontal shelf was newly formed from the medial wall of the preceding vertical-stage shelf during elevation, and that the palatal shelf was elevated by a remodeling process in the anterior half of the shelf.

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Section: Discussionsupporting

confidence: 52%

The Anterior Half of Mouse Palatal Shelf Is Elevated by a Remodeling Movement

Yasuda¹,

Fujimoto²

1986

Cells Tissues Organs

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“…Direct electrical stimulation of the embryonic rat tongue muscles produced relatively weak and slow contractions, whereas stimulation of the hypoglossal nucleus and the suprahyoid muscles produced more vigorous mouthopening movements and tongue protrusion (Wragg et al, 197213). The genioglossus muscle, the major tongue protrusion muscle (Bosma, 1967;Lowe, 19801, was shown to be in the young fiber stage prior to shelf elevation (Wragg et al, 1972b). Since the genioglossus muscle has its origin at the ventral aspect in the anterior region of Meckel's cartilage, contraction of this muscle would have the effect of lowering the body of the tongue and moving it forward.…”

Section: Neuromuscular Movementsmentioning

confidence: 98%

A morphometric analysis of craniofacial growth and changes in spatial relations during secondary palatal development in human embryos and fetuses

Diewert

1983

Am. J. Anat.

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Staged human embryos and fetuses in the Carnegie Embryological Collection were morphometrically analyzed to show craniofacial dimensions and changes in spatial relations, and to identify patterns that would reflect normal developmental events during palatal formation. Normal embryos aged 7-8 weeks postconception (Streeter-O'Rahilly stages 19-23) and fetuses aged 9-10 weeks postconception, in eight groups with mean crown-rump (CR) lengths of 18-49 mm, were studied with cephalometric methods developed for histologic sections. In the 4-week period studied, facial dimensions increased predominantly in the sagittal plane with extensive changes in length (depth) and height, but limited changes in width. Growth of the mandible was more rapid than the nasomaxillary complex, and the length of Meckel's cartilage exceeded the length of the oronasal cavity at the time of horizontal movement of the shelves during stage 23. Simultaneously with shelf elevation, the upper craniofacial complex lifted, and the tongue and Meckel's cartilage extended forward beneath the primary palate. Analysis of spatial relations in the oronasal cavity showed that the palatomaxillary processes became separated from the tongue--mandibular complex as the head extended, and the tongue became positioned forward with growth of Meckel's cartilage. As the head position extended by 35 degrees, the cranial base angulation was unchanged and the primary palate maintained a 90 degrees position to the posterior cranial base. However, the sagittal position of the maxilla relative to the anterior cranial base increased by 20 degrees between stages 19 and 23. In the late embryonic and early fetal periods, the mean cranial base angulation of approximately 128 degrees and the mean maxillary position angulation of approximately 84 degrees were similar to the angulations previously shown to be present later prenatally and post-natally. The results suggest that human patterns of cranial base angulation and maxillary position to the cranial base develop during the late embryonic period when the chondrocranium and Meckel's cartilage form the primary skeleton.

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“…Note the secondary palate is not seen in this midsagittal section since the palatal shelves are not fused and retain a vertical position within the oral cavity. the rodent tongue is functional during this period, and reflex neuromuscular movements have been observed (Wragg et al, 1972). The oral cavity region experiences over a fourfold increase in size as well as undergoing a dramatic shape alteration in the sagittal plane.…”

Section: Intragroup Comparisonmentioning

confidence: 98%

Measuring histological form change with finite element methods: An application using diazo‐oxo‐norleucine (DON)‐treated rats

Lozanoff

Diewert

1986

Am. J. Anat.

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Analyses of drug-induced anatomical malformations routinely rely on linear measurements as a data base. Morphometric approaches utilizing these measures become inappropriate at the histological level at which a constant external referencing system is impossible to achieve. The purpose of this study was to quantify anatomical form change in the craniofacial region of late embryonic rats induced by a known teratogen, diazo-oxo-norleucine (DON), independent of any global referencing system. A sample of 17 untreated specimens of 17-day gestation served as the control. A second group, equivalent in number and age, received 2.0 mg DON on day 15. Homologous landmarks were identified in each specimen and craniofacial regions were partitioned with respect to these bounding nodes into nasal, oral, and mandibular elements. Form change was viewed as the continuous deformation of a reference craniofacial region from a 15-day untreated specimen into each final 17-day geometry. An interactive graphics program generated spatially invariant measures of form change through finite element methods. A local coordinate system was established for each element. A point within each region of the 15-day reference specimen was selected and the spatial relationship between this point and bounding nodes was quantified through interpolation functions. Size and shape variables were derived from a Lagrangian strain tensor, and values were compared between groups. Results showed that all three craniofacial regions were smaller in size among DON-treated specimens, but only oral and mandibular region shapes were different from controls. The finite element approach was considered superior to other histological morphometric techniques since an entire geometry was described and a visual description of form change as well as spatially invariant measures of size and shape change were derived.

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Myoneural maturation and function of the foetal rat tongue at the time of secondary palate closure

Cited by 43 publications

References 13 publications

The Anterior Half of Mouse Palatal Shelf Is Elevated by a Remodeling Movement

The Anterior Half of Mouse Palatal Shelf Is Elevated by a Remodeling Movement

A morphometric analysis of craniofacial growth and changes in spatial relations during secondary palatal development in human embryos and fetuses

Measuring histological form change with finite element methods: An application using diazo‐oxo‐norleucine (DON)‐treated rats

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