File:Bailey305.jpg

From Embryology

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Fig. 305. Transverse section of a dog embryo with 19 primitive segments

Bonnet.

  • Section taken through sixth segment.
  • The pronephric tubules are but transient structures and have no functional significance in man and the higher Vertebrates.
  • The ducts, however, remain and become the ducts of the second set of urinary organs, the mesonephroi.
  • primitive segments = somites.

The pronephros, with the pronephric duct, is the first of the urinary organs to appear. In embryos of 2-3 mm. there are two pronephric tubules on each side, situated at the level of the heart. Although their mode of origin has not been observed in the human embryo, it is probable, judging from observations on lower Vertebrates, that they arise as evaginations of the mesothelium. The part of the mesothelium involved is that adjacent to the intermediate cell mass (Fig. 305) .


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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Reference

Bailey FR. and Miller AM. Text-Book of Embryology (1921) New York: William Wood and Co.



Cite this page: Hill, M.A. (2024, June 14) Embryology Bailey305.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey305.jpg

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current11:11, 25 January 2011Thumbnail for version as of 11:11, 25 January 2011931 × 440 (82 KB)S8600021 (talk | contribs)
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22:16, 23 January 2011Thumbnail for version as of 22:16, 23 January 20111,511 × 1,200 (292 KB)S8600021 (talk | contribs){{Template:Bailey 1921 Figures}} Category:Human Category:Renal