Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart

Normal anatomy of the left atrial appendage (LAA) of human fetus is of a great importance for fetal cardiac surgery and heart bioprinting. Aim of the study was to clarify the mesoscopic anatomy and histotopography of different parts of the LAA walls in normal human fetuses of 16–22 gestation weeks....

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Main Authors: A. A. Gaponov, I. D. Ufimtseva, E. G. Dmitrieva, D. K. Kuznetsov, V. I. Pryakhina, A. A. Iakimov
Format: Article
Language:Russian
Published: Russian Academy of Sciences, Siberian Branch Publishing House 2024-07-01
Series:Сибирский научный медицинский журнал
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Online Access:https://sibmed.elpub.ru/jour/article/view/1548
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author A. A. Gaponov
I. D. Ufimtseva
E. G. Dmitrieva
D. K. Kuznetsov
V. I. Pryakhina
A. A. Iakimov
author_facet A. A. Gaponov
I. D. Ufimtseva
E. G. Dmitrieva
D. K. Kuznetsov
V. I. Pryakhina
A. A. Iakimov
author_sort A. A. Gaponov
collection DOAJ
description Normal anatomy of the left atrial appendage (LAA) of human fetus is of a great importance for fetal cardiac surgery and heart bioprinting. Aim of the study was to clarify the mesoscopic anatomy and histotopography of different parts of the LAA walls in normal human fetuses of 16–22 gestation weeks. Material and methods. We prepared serial histotopograms of the left atrial appendages from 10 normal human fetal hearts stained by Masson trichrome, orcein and fast green. We studied slides by means Olympus CX microscope, TOUPCAM U31S digital camera, and ADF-Image program for measuring. Using a Carl Zeiss EVO LS 10 scanning electron microscope at a magnification of 15–5000 times, three samples were examined using the freeze-chip method. Results. Having measured the outer walls of the LAA intertrabecular spaces, we found that at the level of the middle third of the left atrium, their thickness is minimal in the posterior wall (80 [61–97] μm) (median [lower quartile; upper quartile]), thickness in the anterior wall is 142.9 ± 33.2 μm (mean ± standard deviation) (101 [79–192] μm). At the level of the coronary sulcus, the same parameters were 143.7 ± 23.6 µm (147.5 [90–180] µm) and 137.4 ± 33.9 µm (101 [68–195] µm), respectively. Downward, LAA posterior wall increased about 1.8 in thickness, whereas the thickness of the anterior wall was the same. The endocardium showed the same thickness in all locations. Microanatomically, the LAA myocardium never discovered to build from distinct layers but “anatomical syncytium” or seldom bundles. Collagen and elastic layers were common for endocardium, rare for epicardium. Endocardial elastic fibers interweaved in the underlying collagen so the distinct boundary lacks there. Conclusions. Mesoscopic and microanatomical features of LAA walls in human fetus consist of variable thickness at different levels, unlayered but “syncytial” myocardium, muscleless areas, elastic and collagen layers of the endocardium.
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spelling doaj-art-eab393b9068142a4a24c8ae3e6d4cc4e2025-08-20T03:50:44ZrusRussian Academy of Sciences, Siberian Branch Publishing HouseСибирский научный медицинский журнал2410-25122410-25202024-07-01443687710.18699/SSMJ20240307633Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heartA. A. Gaponov0I. D. Ufimtseva1E. G. Dmitrieva2D. K. Kuznetsov3V. I. Pryakhina4A. A. Iakimov5Ural Federal University named after the first President of Russia B.N. Yeltsin; The Ural State Medical University of Minzdrav of RussiaUral Federal University named after the first President of Russia B.N. YeltsinUral Federal University named after the first President of Russia B.N. Yeltsin; The Ural State Medical University of Minzdrav of RussiaUral Federal University named after the first President of Russia B.N. YeltsinUral Federal University named after the first President of Russia B.N. YeltsinUral Federal University named after the first President of Russia B.N. Yeltsin; The Ural State Medical University of Minzdrav of RussiaNormal anatomy of the left atrial appendage (LAA) of human fetus is of a great importance for fetal cardiac surgery and heart bioprinting. Aim of the study was to clarify the mesoscopic anatomy and histotopography of different parts of the LAA walls in normal human fetuses of 16–22 gestation weeks. Material and methods. We prepared serial histotopograms of the left atrial appendages from 10 normal human fetal hearts stained by Masson trichrome, orcein and fast green. We studied slides by means Olympus CX microscope, TOUPCAM U31S digital camera, and ADF-Image program for measuring. Using a Carl Zeiss EVO LS 10 scanning electron microscope at a magnification of 15–5000 times, three samples were examined using the freeze-chip method. Results. Having measured the outer walls of the LAA intertrabecular spaces, we found that at the level of the middle third of the left atrium, their thickness is minimal in the posterior wall (80 [61–97] μm) (median [lower quartile; upper quartile]), thickness in the anterior wall is 142.9 ± 33.2 μm (mean ± standard deviation) (101 [79–192] μm). At the level of the coronary sulcus, the same parameters were 143.7 ± 23.6 µm (147.5 [90–180] µm) and 137.4 ± 33.9 µm (101 [68–195] µm), respectively. Downward, LAA posterior wall increased about 1.8 in thickness, whereas the thickness of the anterior wall was the same. The endocardium showed the same thickness in all locations. Microanatomically, the LAA myocardium never discovered to build from distinct layers but “anatomical syncytium” or seldom bundles. Collagen and elastic layers were common for endocardium, rare for epicardium. Endocardial elastic fibers interweaved in the underlying collagen so the distinct boundary lacks there. Conclusions. Mesoscopic and microanatomical features of LAA walls in human fetus consist of variable thickness at different levels, unlayered but “syncytial” myocardium, muscleless areas, elastic and collagen layers of the endocardium.https://sibmed.elpub.ru/jour/article/view/1548human anatomyheart anatomyhuman fetusatriaatrial auriclesatrial appendagesmyocardiumendocardiumloose connective tissue of the heart
spellingShingle A. A. Gaponov
I. D. Ufimtseva
E. G. Dmitrieva
D. K. Kuznetsov
V. I. Pryakhina
A. A. Iakimov
Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
Сибирский научный медицинский журнал
human anatomy
heart anatomy
human fetus
atria
atrial auricles
atrial appendages
myocardium
endocardium
loose connective tissue of the heart
title Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
title_full Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
title_fullStr Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
title_full_unstemmed Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
title_short Mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
title_sort mesoscopic anatomy and histotopography of the left atrial appendage walls in human fetal heart
topic human anatomy
heart anatomy
human fetus
atria
atrial auricles
atrial appendages
myocardium
endocardium
loose connective tissue of the heart
url https://sibmed.elpub.ru/jour/article/view/1548
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