Ultrastructural changes in the epithelium during fusion of the palatal processes in rats

Hayward, A.F.

doi:10.1016/0003-9969(69)90188-5

Cited by 75 publications

(23 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the cessation of DNA synthesis in MEE cells may not necessarily be a sign of cell death. Although the intracellular increase in lysosomal enzymes has been observed in a subset of MEE cells prior to or during palatal fusion (Hayward, 1969;Smiley, 1970;Pratt and Greene, 1976), degradative enzymes may be required not only for PCD but also for epithelial-mesenchymal transformation and migration of MEE cells.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, several morphological studies detected degenerated cells in the midline epithelial seam and among disappearing midline epithelial cells (Farbman, 1968;Hayward, 1969;Mato et al, 1972;Pratt and Hassel, 1975). However, the presence of dead cells is not a conclusive evidence of PCD in MEE cells.…”

Section: Discussionmentioning

confidence: 99%

“…The classical hypothesis that cell death is required for palatogenesis has been proposed based on the observations as follows: (1) some MEE cells develop ultrastructural changes that are characteristic to dead cells prior to and/or during palatal fusion (Farbman,1968;Shapiro and Sweney, 1969;Chaudhry and Shah, 1973); (2) MEE cells cease DNA synthesis prior to the fusion of palatal shelves (Hudson and Shapiro, 1973;Pratt and Martin, 1975;Greene and Pratt, 1976); and (3) lysosomal enzyme levels in MEE cells increase prior to or during palatal fusion (Hayward, 1969;Smiley, 1970;Pratt and Greene, 1976). Furthermore, several morphological studies detected degenerated cells in the midline epithelial seam and among disappearing midline epithelial cells (Farbman, 1968;Hayward, 1969;Mato et al, 1972;Pratt and Hassel, 1975).…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Programmed cell death is not a necessary prerequisite for fusion of the fetal mouse palate.

Takahara

Takigawa²,

Shiota³

2004

Int. J. Dev. Biol.

View full text Add to dashboard Cite

It has been widely accepted that programmed cell death (PCD) is an essential event in palatogenesis and that its failure can result in cleft palate, one of the most common birth defects in the human. However, some conflicting results have been reported concerning the timing of cell death occurring in the fusing palate and therefore the role of PCD in palatal fusion is controversial. In order to clarify whether cell death is indispensable for mammalian palatogenesis, we cultivated the palates of day-13 mouse fetuses in vitro and prevented cell death by treating them with the inhibitors of caspases-1 and -3 or with aurintricarboxylic acid which inhibits the activity of caspaseactivated DNase. Even when cell death was almost completely inhibited, palatal fusion took place successfully. Histological examination revealed that in the absence of apoptotic cell death, the medial edge epithelia of opposing palatal shelves adhered to each other and subsequently, the midline epithelial seam was disrupted and disappeared to bring about mesenchymal confluence across the palate. It seems that cell death is not a necessary prerequisite for palatal fusion but it may help to efficiently eliminate unnecessary cells which failed to migrate or differentiate properly.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Programmed cell death is not a necessary prerequisite for fusion of the fetal mouse palate.

Takahara

Takigawa²,

Shiota³

2004

Int. J. Dev. Biol.

View full text Add to dashboard Cite

show abstract

“…The two opposing MEE first come into contact following the rotation to a horizontal posi-tion of the palatal shelves. The pattern of subsequent differentiation of the medial edge epithelium differs from that of the adjacent and continuous oral and nasal epithelia (Farbman, 1968;Hayward, 1969;Mato et al, 1972;Pratt and Hassell, 1975;Tassin et al, 1983). The MEE is committed to a pattern of differentiation that results in the disappearance of these cells from the midline.…”

Section: Fate Of the Medial Edge Epitheliummentioning

confidence: 99%

“…By the mid-1970's, the hypothesis for a programmed cell death fate for the MEE was wellaccepted. That conclusion was based on several studies that used ultrastructural observations of degenerated epithelial cells in the midline seam area and disappearance of epithelial cells from the region of mesenchymal confluence (Farbman, 1968;Hayward, 1969;Mato et al, 1972;Pratt and Hassell, 1975). Interestingly, when these papers are reviewed, the electronmicrographs often contain many perfectly normal-appearing MEE cells without any signs of apoptosis that are either near or adjacent to a degenerated cell.…”

Section: Programmed Cell Heath Of Medial Edge Epitheliummentioning

confidence: 99%

Programmed Cell Death and Cell Transformation in Craniofacial Development

Shuler

1995

Critical Reviews in Oral Biology & Medicine

View full text Add to dashboard Cite

Fusion of branchial arch derivatives is an essential component in the development of craniofacial structures. Bilaterally symmetric branchial arch processes fuse in the midline to form the mandible, lips, and palate. The mechanism for fusion requires several different morphologic and molecular events prior to the completion of the mesenchymal continuity between opposing tissue processes. The ectodermal covering of the branchial arches is one of the cell types that has an important role during craniofacial development. The surface epithelia provide the initial adherence between the processes; however, this population of cells is ultimately absent from the fusion zone. The medial edge epithelium of the secondary palatal shelves is one example of such an epithelium that must disappear from the fusion zone of the secondary palate during development in order to complete palatal fusion. The mechanisms for removal of the epithelial cells from the fusion zone could include either programmed cell death, epithelial-mesenchymal transformation, or migration to adjacent epithelia. All three of these fates have been hypothesized as a mechanism for the removal of the palatal medial edge epithelia. The processes of programmed cell death, epithelial-mesenchymal transformation, and epithelial migration are reviewed with respect to both palatal fusion and results reported in other model systems.

show abstract

Fine structural observations on cell death in the epidermis of the external gills of the larval frog, Rana pipiens

1971

View full text Add to dashboard Cite

The fine structure of the epidermis of the external gills of the larval frog, Rana pipiens, was observed during the period of gill degeneration. Many of the epidermal cells underwent morbid alterations. In typical degenerating epidermal cells the nucleus became irregular in outline, chromatin formed electron-dense clumps and the nuclear envelope increased in width. Lysosomes became prevalent in the cytoplasm of these cells and progressively larger autophagic vacuoles appeared. As degeneration continued, apical epidermal cells were found embedded deeper within the epidermis. In some instances cell processes from two neighboring epidermal cells extended partially around the relocated degenerating apical epidermal cells probably contributing to their translocation; phagocytosis was completed by a single cell in other instances. The degree of participation of the phagocytic epidermal cells in the degenerative process was uncertain. The distribution of acid phosphatase activity was followed in specimens treated by the Gomori technique. Profiles of cisterna-like elements, positive for the enzyme, suggested that perhaps entire Golgi cisternae contributed to the formation of autophagic vacuoles in combination with small vesicles. Heterophils and macrophages observed in the degenerating gills were believed to participate in the removal of the dying cells.The development and degeneration of external gills of both anurans and urodeles were studied by several nineteenth century investigators (Whitney, 1867; Boas, 1882;Maurer, 1888;Naue, 1890; Clemens, 1895). Experimental embryologists of the early twentieth century found amphibian external gills useful organs for studying the interactions between the germ layers of embryos (Ekman, '13; Harrison, '21; Severinghaus, '30; Moser, '40). Physiologists have explored the relationship between the concentration of respiratory gases and the growth of external gills (Drastich, '25; Savage, '61; Boell et al., '63; Lprvtrup and Pigon, '68). However, cellular changes occurring during degeneration of the external gills of anurans have never been reported.The external gills of the larval frog, Rana pipiens, and many other species of anurans are transitory respiratory organs that arise from the third, fourth and fifth visceral arches, just prior to the heart-AM. J. ANAT., 132: 301-318.beat stage. The finger-like external gill filaments consist of an epidermis of two cell layers, connective tissue containing collagenous fibers and scattered mesenchymal cells, and one or more large capillary loops. The gills grow to a maximum length of about 1 mm. After only two or three days of function, the opercular fold begins to enclose them in the opercular chamber. Concurrently, the external gills start to degenerate resulting in their disappearance within five to seven days. The external gills are replaced by internal gills, that presumably take over the respiratory function (Rugh, '51).The external gills of the larval frog are an excellent system for investigation of developmental cell death ...

show abstract

Ultrastructural changes in the epithelium during fusion of the palatal processes in rats

Cited by 75 publications

References 23 publications

Programmed cell death is not a necessary prerequisite for fusion of the fetal mouse palate.

Programmed cell death is not a necessary prerequisite for fusion of the fetal mouse palate.

Programmed Cell Death and Cell Transformation in Craniofacial Development

Fine structural observations on cell death in the epidermis of the external gills of the larval frog, Rana pipiens

Contact Info

Product

Resources

About