Paper - The Development of the Pars Membranacea Septi in the Human Heart: Difference between revisions
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=The Development of the Pars Membranacea Septi in the Human Heart= | |||
By P. N. B. Odgers | |||
From the Department of Human Anatomy, University of Oxford | |||
THE accounts which have been published of the development of this region of | |||
the heart, the method in which the interventricular foramen is occluded to | |||
form the membranous part of the septum, or whether indeed this occurs at all, | |||
have been so vague or so contradictory that a re-examination of the question | |||
seemed worth while. | |||
For this investigation I was able to study human embryos of 11.2, 11.4-, 12.5, 14, 14.5, 15.5, 17, and 17.5 mm. in crown-rump length. Of these the 14 mm. embryo was the least valuable for my present purpose, as the heart is over-distended with blood in this specimen. I have therefore not included it among the detailed descriptions which follow. Reconstruction models were made of this region in the 11.2, 11.4, 14.5, 15.5, and 17 mm. specimens. | |||
==11.2 mm Embryo== | |||
At this stage (Text-fig. 1) the two bulbar ridges (Frazer) or the proximal | |||
bulbar swellings (Tandler) are seen united above to form the bulbar septum, but | |||
soon separating below into right and left moieties. The right one (R.B.R.) can be | |||
traced down on the right ventricular wall to become continuous with the anlage | |||
of the right or inferior cusp of the tricuspid valve, while the left one (L.B.R.) | |||
joins the right side of the interventricular septum and on that soon disappears. | |||
Where they are fused and for a few sections after their separation the two | |||
ridges are seen to be of equal size, but at a. lower level the right one soon appears to be not only the more extensive but the more substantial of the two. | |||
The interventricular foramen (I. V.F.) is seen in thirty sections, i.e. its cranio-caudal diameter is 300 p.. It is bordered ventrally by the inter ventricular septum (I. V.S.) and dorsally by the fused auriculoventricular cushions (hereafter abbreviated into the A.-V. cushions). Above, the dorsal (cranial) border of the interventricular septum joins the fused A.-V. cushions about their centre, while below it joins their right margin. | |||
Below the caudal border of the foramen the septum is fused to the inferior A.-V. cushion in fourteen sections (i.e. for 140 p.). This must presumably represent the amount of closure of the interventricular foramen which has already occurred since about the 7 mm. stage. It may be noted here, however, that in our 7 mm. embryo, where the interventricular septum is represented by a | |||
low ridge which does not yet make contact with the A.-V. cushions, the cranio- | |||
Revision as of 09:56, 19 January 2016
Embryology - 6 May 2024    Expand to Translate
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Odgers PN. The Development of the Pars Membranacea Septi in the Human Heart. J Anat. 1938 Jan;72(Pt 2):247-59. PMID 17104688
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The Development of the Pars Membranacea Septi in the Human Heart
By P. N. B. Odgers
From the Department of Human Anatomy, University of Oxford
THE accounts which have been published of the development of this region of the heart, the method in which the interventricular foramen is occluded to form the membranous part of the septum, or whether indeed this occurs at all, have been so vague or so contradictory that a re-examination of the question seemed worth while.
For this investigation I was able to study human embryos of 11.2, 11.4-, 12.5, 14, 14.5, 15.5, 17, and 17.5 mm. in crown-rump length. Of these the 14 mm. embryo was the least valuable for my present purpose, as the heart is over-distended with blood in this specimen. I have therefore not included it among the detailed descriptions which follow. Reconstruction models were made of this region in the 11.2, 11.4, 14.5, 15.5, and 17 mm. specimens.
11.2 mm Embryo
At this stage (Text-fig. 1) the two bulbar ridges (Frazer) or the proximal bulbar swellings (Tandler) are seen united above to form the bulbar septum, but soon separating below into right and left moieties. The right one (R.B.R.) can be traced down on the right ventricular wall to become continuous with the anlage of the right or inferior cusp of the tricuspid valve, while the left one (L.B.R.) joins the right side of the interventricular septum and on that soon disappears. Where they are fused and for a few sections after their separation the two ridges are seen to be of equal size, but at a. lower level the right one soon appears to be not only the more extensive but the more substantial of the two.
The interventricular foramen (I. V.F.) is seen in thirty sections, i.e. its cranio-caudal diameter is 300 p.. It is bordered ventrally by the inter ventricular septum (I. V.S.) and dorsally by the fused auriculoventricular cushions (hereafter abbreviated into the A.-V. cushions). Above, the dorsal (cranial) border of the interventricular septum joins the fused A.-V. cushions about their centre, while below it joins their right margin.
Below the caudal border of the foramen the septum is fused to the inferior A.-V. cushion in fourteen sections (i.e. for 140 p.). This must presumably represent the amount of closure of the interventricular foramen which has already occurred since about the 7 mm. stage. It may be noted here, however, that in our 7 mm. embryo, where the interventricular septum is represented by a
low ridge which does not yet make contact with the A.-V. cushions, the cranio-
Cite this page: Hill, M.A. (2024, May 6) Embryology Paper - The Development of the Pars Membranacea Septi in the Human Heart. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_Development_of_the_Pars_Membranacea_Septi_in_the_Human_Heart
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
