Development of the ventral body wall in the human embryo

Mekonen, Hayelom K.; Hikspoors, Jill P. J. M.; Mommen, Greet M. C.; Köhler, S. Eleonore; Lamers, Wouter H.

doi:10.1111/joa.12380

Cited by 53 publications

(87 citation statements)

References 55 publications

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“…in Mekonen et al. ). At this time, all ribs pointed ventrolaterally and were of approximately the same length.…”

Section: Resultsmentioning

confidence: 92%

“…in Mekonen et al. ). The ribs had increased in length, with all ribs still showing similar lengths, but their anterior extremities were now pointing ventrally.…”

Section: Resultsmentioning

confidence: 92%

“…in Mekonen et al. ). At CS20, the ribs extended ventromedially and started to form a connection with the sternum in a craniocaudal sequence.…”

Section: Resultsmentioning

confidence: 92%

“…Later stages of vertebral development, such as the development of the rib cage between 5 and 8 weeks (Mekonen et al. ), and the neural processes between 5 and 10 weeks, are used even less frequently. With 3D reconstruction of embryos being increasingly practicable, however, the number of somites and the developmental stage of the rib cage will probably serve more often to stage early human embryos.…”

Section: Introductionmentioning

confidence: 99%

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Closure of the vertebral canal in human embryos and fetuses

et al. 2017

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The vertebral column is the paradigm of the metameric architecture of the vertebrate body. Because the number of somites is a convenient parameter to stage early human embryos, we explored whether the closure of the vertebral canal could be used similarly for staging embryos between 7 and 10 weeks of development. Human embryos (5-10 weeks of development) were visualized using Amira 3D reconstruction and Cinema 4D remodelling software. Vertebral bodies were identifiable as loose mesenchymal structures between the dense mesenchymal intervertebral discs up to 6 weeks and then differentiated into cartilaginous structures in the 7th week. In this week, the dense mesenchymal neural processes also differentiated into cartilaginous structures. Transverse processes became identifiable at 6 weeks. The growth rate of all vertebral bodies was exponential and similar between 6 and 10 weeks, whereas the intervertebral discs hardly increased in size between 6 and 8 weeks and then followed vertebral growth between 8 and 10 weeks. The neural processes extended dorsolaterally (6th week), dorsally (7th week) and finally dorsomedially (8th and 9th weeks) to fuse at the midthoracic level at 9 weeks. From there, fusion extended cranially and caudally in the 10th week. Closure of the foramen magnum required the development of the supraoccipital bone as a craniomedial extension of the exoccipitals (neural processes of occipital vertebra 4), whereas a growth burst of sacral vertebra 1 delayed closure until 15 weeks. Both the cranial- and caudal-most vertebral bodies fused to form the basioccipital (occipital vertebrae 1-4) and sacrum (sacral vertebrae 1-5). In the sacrum, fusion of its so-called alar processes preceded that of the bodies by at least 6 weeks. In conclusion, the highly ordered and substantial changes in shape of the vertebral bodies leading to the formation of the vertebral canal make the development of the spine an excellent, continuous staging system for the (human) embryo between 6 and 10 weeks of development.

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“…in Mekonen et al. ). At this time, all ribs pointed ventrolaterally and were of approximately the same length.…”

Section: Resultsmentioning

confidence: 92%

“…in Mekonen et al. ). The ribs had increased in length, with all ribs still showing similar lengths, but their anterior extremities were now pointing ventrally.…”

Section: Resultsmentioning

confidence: 92%

“…in Mekonen et al. ). At CS20, the ribs extended ventromedially and started to form a connection with the sternum in a craniocaudal sequence.…”

Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Closure of the vertebral canal in human embryos and fetuses

et al. 2017

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“…The elasticity of the abdomen may be limited in the craniocaudal and latero‐lateral directions, as the abdominal muscles such as the rectus and external and internal oblique muscles develop before the return phase (Mekonen et al. ; Warmbrunn et al. ).…”

Section: Discussionmentioning

confidence: 99%

Return of the intestinal loop to the abdominal coelom after physiological umbilical herniation in the early fetal period

Nagata

Hatta

et al. 2019

Journal of Anatomy

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The intestine elongates during the early fetal period, herniates into the extraembryonic coelom, and subsequently returns to the abdominal coelom. The manner of herniation is well‐known; however, the process by which the intestinal loop returns to the abdomen is not clear. Thus, the present study was designed to document and measure intestinal movements in the early fetal period in three dimensions to elucidate the intestinal loop return process. Magnetic resonance images from human fetuses whose intestinal loops herniated (herniated phase; n = 5) while returning to the abdominal coelom [transition phase; n = 3, crown–rump length (CRL)] 37, 41, and 43 mm] and those whose intestinal loops returned to the abdominal coelom normally (return phase; n = 12) were selected from the Kyoto Collection. Intestinal return began from proximal to distal in samples with CRL of 37 mm. Only the ileum ends were observed in the extraembryonic coelom in samples with CRLs of 41 and 43 mm, whereas the ceca were already located in the abdominal coeloms. The entire intestinal tract had returned to the abdominal coelom in samples with CRL > 43 mm. The intestinal length increased almost linearly with fetal growth irrespective of the phase (R2 = 0.90). The ratio of the intestinal length in the extraembryonic coelom to the entire intestinal length was maximal in samples with CRLs of 32 mm (77%). This ratio rapidly decreased in three of the samples that were in the transition phase. The abdominal volumes increased exponentially (to the third power) during development. The intestinal volumes accounted for 33–41% of the abdominal volumes among samples in the herniated phase. The proportion of the intestine in the abdominal cavity increased, whereas that in the liver decreased, both without any break or plateau. The amount of space available for the intestine by the end of the transition phase was approximately 200 mm3. The amount of space available for the intestine in the abdominal coelom appeared to be sufficient at the beginning of the return phase in samples with CRLs of approximately 43 mm compared with the maximum intestinal volume available for the extraembryonic coelom in the herniated phase, which was 25.8 mm3 in samples with CRLs of 32 mm. A rapid increase in the space available for the intestine in the abdominal coelom that exceeded the intestinal volume in the extraembryonic coelom generated an inward force, leading to a ‘sucked back’ mechanism acting as the driving force. The height of the hernia tip increased to 8.9 mm at a maximum fetal CRL of 37 mm. The height of the umbilical ring increased in a stepwise manner between the transition and return phases and its height in the return phase was comparable to or higher than that of the hernia tip during the herniation phase. We surmised that the space was generated in the aforementioned manner to accommodate the herniated portion of the intestine, much like the intestine wrapping into the abdominal coelom as the height of the umbilical ring increased.

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Relationship Between Physiological Umbilical Herniation and Liver Morphogenesis During the Human Embryonic Period: A Morphological and Morphometric Study

Kanahashi

Yamada

Yoneyama³

et al. 2019

The Anatomical Record

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It is widely hypothesized that physiological umbilical herniation (PUH) in humans occurs, because the liver occupies a large space in the abdominal cavity, which pushes the intestine into the extraembryonic coelom during the embryonic period. We have recently shown the presence of the intestinal loop in the extraembryonic coelom in embryos with liver malformation. Here, we analyzed the relationship between the liver and the PUH at Carnegie stage 21 of four embryos with liver malformation, including two with hypogenesis (HY1, HY2) and two with agenesis (AG1, AG2), using phase-contrast X-ray computed tomography and compared them with two control embryos. The intestinal loop morphology in the malformed embryos differed from that in the control embryos, except in HY1. The length of the digestive tract in the extraembryonic coelom of the embryos with liver malformation was similar to or longer than that of the controls. The rate of intestinal loop lengthening in the extraembryonic coelom compared with that of the total digestive tract in all embryos with liver malformation was similar to or higher than that of the controls. The estimated total abdominal cavity volume in the embryos with liver malformation was considerably smaller than that of the controls, while the intestinal volume was similar. The cardia and proximal portion of the pancreas connecting to the duodenum were located at almost identical positions in all the embryos, whereas other parts of the upper digestive tract deviated in the embryos with abnormal livers. Thus, our results provided evidence that PUH occurred independently of liver volume.

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Development of the ventral body wall in the human embryo

Cited by 53 publications

References 55 publications

Closure of the vertebral canal in human embryos and fetuses

Closure of the vertebral canal in human embryos and fetuses

Return of the intestinal loop to the abdominal coelom after physiological umbilical herniation in the early fetal period

Relationship Between Physiological Umbilical Herniation and Liver Morphogenesis During the Human Embryonic Period: A Morphological and Morphometric Study

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