The foramen ovale of the foetal and neonatal foal.
Abstract: Hearts from 24 foals were studied; 10 were from foetuses ranging in gestational age from 230 to 322 days and 14 were from newborn and young foals aged between birth and 17 days. The foramen ovale and associated vena caval and atrial structures were examined by scanning electron microscopy. Additional observations were made by light and transmission electron microscopy. A tube-like flap of tissue was observed, extending from the aperture in the caudal vena cava to the lumen of the left atrium. In the younger foetuses, the distal end of this tube was covered with a thread-like network of tissue. In animals nearer to term, the network was replaced by distal fenestrations. Protrusions were seen on the rim of the opening of the tube as it entered the atrium. The role that these may play, together with the significance of cardiac muscle and non-elastic connective tissue in the wall of the tube, were discussed with respect to possible mechanisms of closure of the foramen ovale.
Publication Date: 1988-07-01 PubMed ID: 3168985DOI: 10.1111/j.2042-3306.1988.tb01517.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates the structure and function of the foramen ovale in foetal and newborn horses. The study was conducted on the hearts of 24 foals, using electron and light microscopy to understand how the foramen ovale behaves and changes over time.
Research Methodology
- Hearts from 24 foals were analyzed; 10 of these were from foetuses at various gestation periods, and the rest from newborn and young foals up to 17 days old.
- The main research tools were scanning electron microscopy for the broad observation of the foramen ovale and its related structures, and light and transmission electron microscopy for detailed observations.
Findings and Observations
- In all samples, researchers detected a tube-like flap of tissue stretching from the opening in the caudal vena cava (a large vein carrying deoxygenated blood into the heart) to the lumen of the left atrium (a chamber on the left side of the heart).
- In younger foetuses, the end of this tube was shielded by a delicate tissue network, though this was replaced by distal fenestrations (small openings or holes) in individuals closer to term.
- Protrusions were identified on the edge of the tube’s opening as it entered the atrium.
Interpretation and Significance
- The alterations observed in the tube-like tissue, specifically the replacement of the tissue network with fenestrations as the foetus matured, indicate a changing function of the foramen ovale towards birth. In mammals, the foramen ovale allows blood to bypass the nonfunctional lungs in the foetus, and it usually closes shortly after birth when the lungs become functional.
- The presence of protrusions at the rim of the tube’s opening into the atrium as well as the existence of cardiac muscle and non-elastic connective tissue in the tube’s wall may play roles in the closing of the foramen ovale post-birth.
- This research provides significant insight into the structural and functional transformation of the foramen ovale from a foetal to a postnatal stage, which is crucial for understanding normal heart development and diagnosing diseases related to the foramen ovale’s function in horses and potentially other mammals.
Cite This Article
APA
MacDonald AA, Fowden AL, Silver M, Ousey J, Rossdale PD.
(1988).
The foramen ovale of the foetal and neonatal foal.
Equine Vet J, 20(4), 255-260.
https://doi.org/10.1111/j.2042-3306.1988.tb01517.x Publication
Researcher Affiliations
- Department of Preclinical Veterinary Sciences, University of Edinburgh, Summerhall.
MeSH Terms
- Animals
- Animals, Newborn / anatomy & histology
- Fetal Heart / anatomy & histology
- Fetal Heart / ultrastructure
- Heart Septum / anatomy & histology
- Heart Septum / ultrastructure
- Horses / anatomy & histology
- Microscopy, Electron, Scanning
Grant Funding
- Wellcome Trust
Citations
This article has been cited 6 times.- De Lange L, Vernemmen I, van Loon G, Decloedt A. Echocardiographic Features of the Ductus Arteriosus and the Foramen Ovale in a Hospital-Based Population of Neonatal Foals. Animals (Basel) 2022 Aug 30;12(17).
- Vernemmen I, Paulussen E, Dauvillier J, Decloedt A, van Loon G. Three-dimensional and catheter-based intracardiac echocardiographic characterization of the interatrial septum in 2 horses with suspicion of a patent foramen ovale. J Vet Intern Med 2022 Jul;36(4):1535-1542.
- Jensen B, Wang T, Moorman AFM. Evolution and Development of the Atrial Septum. Anat Rec (Hoboken) 2019 Jan;302(1):32-48.
- Macdonald AA, Carr PA, Currie RJ. Comparative anatomy of the foramen ovale in the hearts of cetaceans. J Anat 2007 Jul;211(1):64-77.
- Macdonald AA, Johnstone M. Comparative anatomy of the cardiac foramen ovale in cats (Felidae), dogs (Canidae), bears (Ursidae) and hyaenas (Hyaenidae). J Anat 1995 Apr;186 ( Pt 2)(Pt 2):235-43.
- Macdonald AA. Comparative anatomy of the foramen ovale in the Suina. Anat Embryol (Berl) 1988;178(1):53-7.
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