Differentiation and innervation of the atrioventricular bundle and ventricular Purkinje system in sheep heart

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 641-651
Author(s):  
E. Canale ◽  
J.J. Smolich ◽  
G.R. Campbell
Keyword(s):  
Intermediate Filaments ◽  
Morphological Changes ◽  
Atrioventricular Node ◽  
Ventricular Wall ◽  
Nerve Fibres ◽  
Fetal Sheep ◽  
Purkinje Fibres ◽  
Developmental Mechanism ◽  
Purkinje System ◽  
Atrioventricular Bundle

The development of the atrioventricular bundle (AVB) and ventricular Purkinje system and their innervation have been studied in fetal sheep from 27 to 140 days gestation (term is 147 days). The AVB initially consisted of a primordium, which lacked innervation and was composed of small, relatively undifferentiated myocytes. Differentiation of Purkinje-like cells within the AVB began near its distal end and extended towards the atrioventricular node (AVN). Differentiation of the ventricular Purkinje system extended distally from the region of bifurcation of the AVB from cells that were indistinguishable from the working myocardium and continuous with the AVB primordium. Differentiation of Purkinje-like AVB cells was complete by 46 days gestation but Purkinje fibres were still differentiating within the ventricular wall at 60 days gestation. The main morphological changes included a large increase in cell size and organization into strands, development of characteristic glycogen-filled regions containing many intermediate filaments and early development of myofibrillar M lines compared to the working myocardium. The differentiation of AVB cells and the ventricular Purkinje system preceded their innervation. The AVB became innervated earlier than ventricular Purkinje fibres, intimate contacts between proximal AVB cells and nerve axons being present at 60 days gestation. Nerve fibres were present in the septomarginal band at this time, however, en passant associations with ventricular Purkinje fibres were rarely observed until 140 days gestation and intimate contacts were not present at any stage. Although the AVB and ventricular Purkinje system of adult sheep are composed of morphologically similar cells, the present study demonstrates that they differ in origin and their mode of differentiation as well as timing and intimacy of innervation. Innervation is not part of the developmental mechanism leading to the differentiation of Purkinje fibres. No primordium of the ventricular Purkinje system could be identified, suggesting that the mechanism of differentiation of ventricular Purkinje fibres involves recruitment from early working myocardium.

The spatial distribution and relative abundance of gap-junctional connexin40 and connexin43 correlate to functional properties of components of the cardiac atrioventricular conduction system

1993 ◽  
Vol 105 (4) ◽  
pp. 985-991 ◽  
Author(s):  
R.G. Gourdie ◽  
N.J. Severs ◽  
C.R. Green ◽  
S. Rothery ◽  
P. Germroth ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Relative Abundance ◽  
Atrioventricular Node ◽  
Conduction System ◽  
Atrioventricular Conduction ◽  
Purkinje Fibre ◽  
Purkinje Fibres ◽  
Atrioventricular Bundle ◽  
Junctional Protein ◽  
Gap Junctional

Electrical coupling between heart muscle cells is mediated by specialised regions of sarcolemmal interaction termed gap junctions. In previous work, we have demonstrated that connexin42, a recently identified gap-junctional protein, is present in the specialised conduction tissues of the avian heart. In the present study, the spatial distribution of the mammalian homologue of this protein, connexin40, was examined using immunofluorescence, confocal scanning laser microscopy and quantitative digital image analysis in order to determine whether a parallel distribution occurs in rat. Connexin40 was detected by immunofluorescence in all main components of the atrioventricular conduction system including the atrioventricular node, atrioventricular bundle, and Purkinje fibres. Quantitation revealed that levels of connexin40 immunofluorescence increased along the axis of atrioventricular conduction, rising over 10-fold between atrioventricular node and atrioventricular bundle and a further 10-fold between atrioventricular bundle and Purkinje fibres. Connexin40 and connexin43, the principal gap-junctional protein of the mammalian heart, were co-localised within atrioventricular nodal tissues and Purkinje fibres. By applying a novel photobleach/double-labelling protocol, it was demonstrated that connexin40 and connexin43 are co-localised in precisely the same Purkinje fibre myocytes. A model, integrating data on the spatial distribution and relative abundance of connexin40 and connexin43 in the heart, proposes how myocyte-type-specific patterns of connexin isform expression account for the electrical continuity of cardiac atrioventricular conduction.

scholarly journals A Novel Model of Cancer-Induced Peripheral Neuropathy and the Role of TRPA1 in Pain Transduction

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Ahmad Maqboul ◽  
Bakheet Elsadek
Keyword(s):  
Immune Cells ◽  
Peripheral Nerves ◽  
Morphological Changes ◽  
Nerve Fibres ◽  
Cold Allodynia ◽  
Sciatic Nerves ◽  
Pain Transduction ◽  
Thermal Stimuli ◽  
Novel Model

Background. Models of cancer-induced neuropathy are designed by injecting cancer cells near the peripheral nerves. The interference of tissue-resident immune cells does not allow a direct contact with nerve fibres which affects the tumor microenvironment and the invasion process. Methods. Anaplastic tumor-1 (AT-1) cells were inoculated within the sciatic nerves (SNs) of male Copenhagen rats. Lumbar dorsal root ganglia (DRGs) and the SNs were collected on days 3, 7, 14, and 21. SN tissues were examined for morphological changes and DRG tissues for immunofluorescence, electrophoretic tendency, and mRNA quantification. Hypersensitivities to cold, mechanical, and thermal stimuli were determined. HC-030031, a selective TRPA1 antagonist, was used to treat cold allodynia. Results. Nociception thresholds were identified on day 6. Immunofluorescent micrographs showed overexpression of TRPA1 on days 7 and 14 and of CGRP on day 14 until day 21. Both TRPA1 and CGRP were coexpressed on the same cells. Immunoblots exhibited an increase in TRPA1 expression on day 14. TRPA1 mRNA underwent an increase on day 7 (normalized to 18S). Injection of HC-030031 transiently reversed the cold allodynia. Conclusion. A novel and a promising model of cancer-induced neuropathy was established, and the role of TRPA1 and CGRP in pain transduction was examined.

scholarly journals Characterisation of Morphology in Musculus Semitendinosus Tendon Used for Anterior Cruciate Ligament Reconstruction: A Pilot Study

2020 ◽  
Vol 18 (1) ◽  
pp. 1-6
Author(s):  
Janis Davis Osipovs ◽  
Mara Pilmane ◽  
Modris Ciems
Keyword(s):  
Anterior Cruciate Ligament ◽  
Morphological Changes ◽  
Cruciate Ligament ◽  
Collagen I ◽  
Collagen Fibres ◽  
Nerve Fibres ◽  
Tissue Ischemia ◽  
Moderate Number ◽  
Collagen Iii ◽  
Anterior Cruciate

SummaryIntroductionAnterior cruciate ligament (ACL) rupture is very common in athletes. In the general population, incidence is approximately 33 per 100 000 people.Aim of the studyThe aim of the study was the evaluation of morphological changes in the musculus semitendinosus tendon used for the reconstruction of ACL to understand the quality of most common for surgery used material.Material and methodsThe materials were obtained from four ACL autologous hamstring reconstruction surgeries. The tissue was stained with hematoxyllin and eosin and with immunohistochemical (IMH) staining of PGP9.5, VEGF, collagen I and collagen III. The material was evaluated with semiquantitative method.ResultsRoutine staining showed practically unchanged tendon structure, with one exception when sclerotic blood vessels were observed in endotenon. Collagen III IMH demonstrated moderate to numerous positive collagen fibres in two cases, but in other two there were only few positive structures seen. Collagen I IMH showed few to moderate number of positive collagen fibres in all cases. In two cases, moderate number of PGP9.5 positive nerve fibres was observed and in two other cases occasional to few number of positive structures was detected. PGP 9.5 marked higher number of nerve fibres in peritenon than in endotenon. Numerous VEGF positive endotheliocytes were observed in two cases, but in two other cases VEGF positive endotheliocytes were occasional.ConclusionsTendon of musculus semitendinosus displays two patterns of distribution of tissue ischemia, neuropeptide containing innervation and collagen I and III. Collagen III is thought to be evaluated as a response of tendon to the ischemia and intensive innervation, while increase of collagen I probably is related to the relatively unchanged vascularity and innervation. The pattern of musculus semitendinosus tendon structural changes seems to be connected to the individual homeostasis in patients persisting before the usage of tendon for the reconstruction.

Concealed accessory pathways and related tachycardias

ESC CardioMed ◽  
2018 ◽  
pp. 2091-2092
Author(s):  
Carlo Pappone ◽  
Vincenzo Santinelli
Keyword(s):  
Catheter Ablation ◽  
Radiofrequency Catheter Ablation ◽  
Atrioventricular Node ◽  
Tricuspid Annulus ◽  
Atrioventricular Reentrant Tachycardia ◽  
Accessory Pathways ◽  
Purkinje System ◽  
Electrical Impulses ◽  
Supraventricular Tachycardias ◽  
Retrograde Conduction

Conduction from the atria to the ventricles normally occurs via the atrioventricular node–His–Purkinje system. Accessory pathways (APs) directly connect the atrium and ventricle and bypass the atrioventricular node, bridging the mitral or, less commonly, the tricuspid annulus. Concealed APs conduct electrical impulses retrogradely from the ventricles to the atria, but not antegradely from the atria to the ventricles. Approximately 40% of all APs are concealed, and orthodromic atrioventricular reentrant tachycardia due to concealed APs is present in up to 15% of patients with supraventricular tachycardias referred for catheter ablation. Most concealed APs are left-sided, exhibiting non-decremental retrograde conduction. Tachyarrhythmias due to concealed APs are managed similarly to those supraventricular tachycardias associated with manifest APs, and symptomatic tachyarrhythmias are successfully treated by radiofrequency catheter ablation in the majority of patients.

scholarly journals THE EXTENT OF THE CAPILLARY BED OF THE HEART

1928 ◽  
Vol 47 (2) ◽  
pp. 273-290 ◽  
Author(s):  
Joseph T. Wearn ◽  
Keyword(s):  
Skeletal Muscle ◽  
Blood Supply ◽  
Aortic Wall ◽  
Ventricular Wall ◽  
Papillary Muscles ◽  
Normal Heart ◽  
Purkinje System ◽  
Capillary Bed ◽  
Abundant Supply ◽  
Muscle Capillaries

By means of injections made into the coronary arteries of beating hearts it has been possible to determine the number of capillaries in the normal heart muscle. This study has shown a very rich blood supply with an average of approximately one capillary for each muscle fibre in the ventricular walls and papillary muscles, and a less abundant supply in the auricular muscle and Purkinje system. The number of capillaries per sq. mm. of ventricular wall or papillary muscle is about twice that found by Krogh in skeletal muscle. Capillaries were not found constantly in the valves of hearts in which there was apparently a complete injection of the capillary bed. The method described for injecting the capillaries of the heart also provides a means of studying the blood supply to the muscle, valves and aortic wall in pathological hearts.

Immunoexpression of intermediate filaments and morphological changes in the liver and bile duct of rats infected withFasciola hepatica

2015 ◽  
Vol 90 (7) ◽  
pp. 477-485 ◽  
Author(s):  
L Kolodziejczyk ◽  
M Laszczyńska ◽  
M Masiuk ◽  
M Grabowska ◽  
E Skrzydlewska
Keyword(s):  
Bile Duct ◽  
Intermediate Filaments ◽  
Morphological Changes

MORPHOLOGICAL CHANGES IN UNMYELINATED NERVE FIBRES IN THE SURAL NERVE WITH AGE

Brain ◽  
1991 ◽  
Vol 114 (1) ◽  
pp. 585-599 ◽  
Author(s):  
TAKASHI KANDA ◽  
HIROSHI TSUKAGOSHI ◽  
MASAYA ODA ◽  
KAZUHITO MIYAMOTO ◽  
HITOSHI TANABE
Keyword(s):  
Sural Nerve ◽  
Morphological Changes ◽  
Nerve Fibres ◽  
Unmyelinated Nerve
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