Clarification of the process of separation of the cloaca into rectum and urogenital sinus in the rat embryo

Qi, Bao Quan; Williams, Andrew K.; Beasley, Spencer W.; Frizelle, F. A.

doi:10.1053/jpsu.2000.19265

Cited by 46 publications

(46 citation statements)

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“…The present study also examined distribution of apoptotic cells and bodies in the cloacal region. Distribution of apoptosis in the epithelial layers has already been reported by Qi et al (2000b), and the present findings are similar. However, spatial and temporal distribution of apoptosis in the mesenchyme remains unclear.…”

supporting

confidence: 93%

“…In order to explain the process of normal cloacal developmental, the concept of the descending superior septum, or Tourneux fold (Tourneux, 1888), and two lateral ridges, or Rathke plicae (Rathke, 1832;Rettere, 1890), fusing to partition the cloaca was proposed long ago. Many authors have supported the concept that one or two of these processes take place during cloacal development (Keibel, 1895;Pohlman, 1911;De Vries andFriedland, 1974a, 1974b;Stephens and Smith, 1988;Miller and Briglin, 1996;Kromer, 1999;Qi et al, 2000aQi et al, , 2000bQi et al, , 2000c. This means that the superior urorectal septum reaches the cloacal membrane and divides the cloaca, and the two lateral folds unite with the superior fold to form a complete septum.…”

Section: Observation Of Normal Cloacal Developmentmentioning

confidence: 97%

“…In addition, the cloacal membrane was divided into separate urogenital and anal membranes by the septum. Miller and Briglin (1996) and Qi et al (2000aQi et al ( , 2000bQi et al ( , 2000c mentioned that soon after fusion of the urorectal septum with the cloacal membrane, the urogenital and anal membranes begin to disintegrate. In contrast, Politzer (1931) had already rejected the separation into anal and urogenital membranes.…”

Section: Observation Of Normal Cloacal Developmentmentioning

confidence: 99%

“…In addition, for the formation of various structures during morphogenesis, cell death occurs according to precise temporal sequences and spatial patterns and is considered to play a key role by elim- inating unnecessary cells to achieve complex histogenesis and organogenesis. For example, cell death is involved in remodeling the embryonic tail bud in humans (Kunimoto, 1918;Wittman et al, 1972;Fallon and Simandl, 1978), mice (Wittman et al, 1972;Schoenwolf, 1984;Tam, 1984), rats (Butcher, 1929;Gajović et al, 1989Gajović et al, , 1993Qi et al, 2000b), and chicks (Klika and Jelinik, 1969;Van Horn, 1971;Schoenwolf, 1981;Sanders et al, 1986;Mills and Bellairs, 1989;Miller and Briglin, 1996). Several investigators have indicated that cell death is involved in removal of the tailgut in chicks (Van Horn, 1971), rats (Š vajger et al, 1985), and humans (Fallon and Simandl, 1978).…”

Section: Spatiotemporal Distribution Of Apoptosis In Cloacal Developmentmentioning

confidence: 99%

“…The most debated point is whether fusion of the urorectal septum with the cloacal membrane occurs in normal development (Keibel, 1895;Pohlman, 1911;Politzer, 1931;De Vries andFriedland, 1974a, 1974b;Van der Putte and Neeteson, 1983;Van der Putte, 1986;Stephens and Smith, 1988;Kluth et al, 1995;Miller and Briglin, 1996;Nievelstein et al, 1998;Kromer, 1999;Paidas et al, 1999;Qi et al, 2000aQi et al, , 2000bQi et al, , 2000c. In addition, discussion has also centered around whether the cloacal membrane is divided into urogenital and anal membranes by the urorectal septum.…”

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confidence: 99%

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Spatiotemporal distribution of apoptosis during normal cloacal development in mice

2004

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To understand normal cloacal developmental processes, serial sagittal sections of mouse embryos were made every 6 hrs from embryonic day 11.5 (E11.5) to E13.5. During cloacal development to form the urogenital sinus and anorectal canal, fusion of the urorectal septum with the cloacal membrane was not observed, and the ventral and dorsal parts of the cloaca were continuously connected by the canal until disappearance of the cloacal membrane to open the vestibule formed by the urogenital sinus and anorectal canal to the outside at E13.5. Ventral shifting of the dorsal part of the cloaca was observed until E12.5. The dorsal part was transformed in accordance with ventral shifting. In addition, apoptosis was seen to occur around the dorsal part. However, from E12.25, apoptotic cells are observed in a linear arrangement in the urorectal septum just ventral to the peritoneal cavity. Interestingly, extension of this line reaches the area of the cloacal membrane disintegrated by apoptosis. The present findings suggest that in the early stages (until E12.0), distribution of apoptosis in mesenchyme around the dorsal part of the cloaca might be strongly related to the transformation and ventral shifting of this part. Conversely, the apoptosis pattern in urorectal septum mesenchyme in later stages (from E12.0) might be involved in transformation of the urorectal septum and disintegration of the cloacal membrane.

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supporting

confidence: 93%

Section: Observation Of Normal Cloacal Developmentmentioning

confidence: 97%

Section: Observation Of Normal Cloacal Developmentmentioning

confidence: 99%

Section: Spatiotemporal Distribution Of Apoptosis In Cloacal Developmentmentioning

confidence: 99%

mentioning

confidence: 99%

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Spatiotemporal distribution of apoptosis during normal cloacal development in mice

2004

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Epithelial and Muscular Regionalization of the Human Developing Anorectum

Fritsch

Aigner

Ludwikowski

et al. 2007

The Anatomical Record

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In the past, interpretations of anorectal development were mainly based on analysis of serially sectioned embryos of various nonhuman species as well as some human specimens. A four-dimensional view of the developmental situation in the human has never been established nor connected to recent findings obtained from newer molecular techniques. We, therefore, investigated human embryonic and fetal pelves by means of immunohistochemistry and in situ hybridization to elucidate differentiation and interaction of epithelial and mesenchymal layers of the anorectum. To emphasize spatial as well as sequential morphological development, we produced three-dimensional reconstructions of the specimens at hand. Research conducted proved that the decisive steps of epithelial and muscular differentiation occur between the 7th and 9th week after conception. This study elucidates a biphasic epithelial ''closure'' in the anal canal and interactions between epithelium, smooth musculature, and skeletal musculature. Based on the results presented here, it is possible to describe the pathogenesis of two anorectal malformations: the imperforate anal membrane and the anal membrane stenosis. This study will now provide the basis for further research into developmental processes occurring before the ones examined.

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Perineal groove: A rare congenital abnormality of failure of fusion of the perineal raphe and discussion of its embryological origin

Sekaran

Shawis

2009

Clinical Anatomy

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Clarification of the process of separation of the cloaca into rectum and urogenital sinus in the rat embryo

Cited by 46 publications

References 5 publications

Spatiotemporal distribution of apoptosis during normal cloacal development in mice

Spatiotemporal distribution of apoptosis during normal cloacal development in mice

Epithelial and Muscular Regionalization of the Human Developing Anorectum

Perineal groove: A rare congenital abnormality of failure of fusion of the perineal raphe and discussion of its embryological origin

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