Conus Arteriosus Research Articles

Relationship between diagnosis of conus arteriosus malformation and genetic diagnosis results in fetal cardiac axis abnormalities by echocardiography during middle pregnancy.

To explore the clinical value of echocardiography in detecting fetal cardiac axis abnormalities during middle pregnancy for diagnosing conus arteriosus malformation, and to compare and analyze the genetic diagnosis results, in order to provide evidence for clinical diagnosis and intervention. Four hundred twenty-one fetuses with conus arteriosus malformation from January 2020 to October 2023 were included as the conus arteriosus malformation group, and 917 healthy fetuses (all single fetuses) matched at the same gestational age were selected as the healthy group. There was no significant difference in gestational weeks between two groups (P > 0.05). The age of pregnant women in conus arteriosus malformation group was lower compared to healthy group (P < 0.05), and the fetal cardiac axis in conus arteriosus malformation group was significantly higher compared to healthy group (P < 0.05). Among the fetuses with conus arteriosus malformation, tetralogy of Fallot (TOF), transposition of the great arteries (TGA) and double outlet right ventricle (DORV) had the highest proportions, accounting for 38.00%, 18.29% and 17.58%, respectively. Among all types of conus arteriosus malformations, atresia pulmonary valve syndrome associated with TOF, persistent truncus arteriosus and DORV exhibited higher proportions of fetal cardiac axis abnormalities, at 75.00%, 36.84% and 27.03%, respectively, while TGA and interrupted aortic arch associated with B-type interruption had lower proportions of fetal cardiac axis abnormalities, at 2.60% and 4.55%, respectively. Genetic testing was conducted on 73 cases (17.34%) of fetuses with conus arteriosus malformation in this study. Among them, fetal cardiac axis abnormalities were considered positive for genetic results due to factors such as aneuploidy, copy number abnormalities, and single-gene pathogenicity. A total of 31 cases tested positive for genetic anomalies, with a positive rate of approximately 42.47%. In the middle pregnancy, the fetal cardiac axis in cases of conus arteriosus malformation was significantly higher than in normal fetuses. Moreover, there were variations in fetal cardiac axis among different types of conus arteriosus malformations, and these differences were notably associated with genetic diagnostic results.

Autonomic neuro-cardiac profile of electrical, structural and neuronal remodeling in myocardial infarction-induced heart failure.

Heart failure is a clinical syndrome typified by abnormal autonomic tone, impaired ventricular function, and increased arrhythmic vulnerability. This study aims to examine electrophysiological, structural and neuronal remodeling following myocardial infarction in a rabbit heart failure model to establish its neuro-cardiac profile. Weight-matched adult male New Zealand White rabbits (3.2±0.1kg, n=25) were randomized to have coronary ligation surgeries (HF group, n=13) or sham procedures (SHM group, n=12). Transthoracic echocardiography was performed six weeks post-operatively. On week 8, dual-innervated Langendorff-perfused heart preparations were set up for terminal experiments. Seventeen hearts (HF group, n=10) underwent ex-vivo cardiac MRI. Twenty-two hearts (HF group, n=7) were examined histologically. Electrical remodeling and abnormal autonomic profile were evident in HF rabbits with exaggerated sympathetic and attenuated vagal effect on ventricular fibrillation threshold, ventricular refractoriness and restitution curves, in addition to increased spatial restitution dispersion. Histologically, there was significant neuronal enlargement at the heart hila and conus arteriosus in HF. Structural remodeling was characterized by quantifiable myocardial scarring, enlarged left ventricles, altered ventricular geometry and impaired contractility. In an infarct-induced rabbit heart failure model, extensive structural, neuronal and electrophysiological remodeling in conjunction with abnormal autonomic profile provide substrates for ventricular arrhythmias.

A cadaveric study of arteriovenous trigone of heart: the triangle of Brocq and Mouchet.

Left coronary artery divides into anterior interventricular branch and circumflex branch. As both the arteries run in their corresponding grooves, an arteriovenous trigone is formed between conus arteriosus and left auricle called triangle of Brocq and Mouchet. The triangle base is formed by great cardiac vein. This study aims to describe the frequency of triangle and its type and relationship between various boundaries and content of triangle and to supplement the existing knowledge of clinicians. This observational and descriptive study was conducted on 40 formalin fixed cadaveric hearts in department of anatomy, Kalpana chawla government medical college. The triangle was found in 92.5% of specimen with most common type being closed (51.3%) which is followed by inferiorly open in 35.1%, superiorly open in 8.1% and completely open in 5.4% hearts. Most frequent content of triangle was median artery followed by diagonal branches of anterior interventricular and circumflex branches. The mean area of the triangle was 246.3 mm2. Relationship of vein with two arterial branches was either superficial or deep. The knowledge of different patterns of existence will be required for angiographic procedures. Further the triangle is a potential epicardial access route to left fibrous ring. Thus detailed knowledge of variations will help cardiologist to achieve better outcome in interventional procedures with minimal complications.

Prenatal diagnosis and mRNA profiles of fetal tetralogy of Fallot

Tetralogy of fallot (TOF) in the fetus is a typical congential heart disease that occurs during the early embryonic period, being characterized by the abnormal development of conus arteriosus. The early diagnosis and prevention of fetal TOF is very important and there is a great need for exploring the pathogenesis of it in clinic. In this study, there were three cases being detected with TOF by fetal echocardiogram and confirmed by autopsy. We characterize the difference of expression of lncRNAs and mRNAs through sequencing analysis of 3 pairs of myocardial tissues of fetal TOF and those of age-matched controls. Compared with normal group, there were 94 differentially expressed lncRNAs and 83 mRNA transcripts in TOF (P < 0.05). Correlation analysis between lncRNA and mRNA further showed that differentially expressed lncRNA can be linked to mRNAs, suggesting the potential regulator role of lncRNA in mRNA expression. Our data serve as a fundamental resource for understanding the disease etiology of TOF.

Comparative gross anatomy of epicardiac ganglionated nerve plexi on the human and sheep cardiac ventricles.

This study aimed to examine the distribution and quantitative parameters of the epicardiac ventricular neural ganglionated plexus in the hearts of humans and sheep, highlighting the differences of this plexus in humans and large models. Five non-sectioned pressure distended whole hearts of the human newborns and 10 hearts of newborn German black-faced lambs were investigated applying a histochemical method for acetylcholinesterase to stain epicardiac neural structures with their subsequent stereomicroscopic examination. In humans, the ventricular nerves are spread by four epicardiac nerve subplexuses, that is, the left and right coronary as well as the left and middle dorsal. In sheep, the ventricular nerves are spread by five epicardiac nerve subplexuses, that is, the left and right coronary, the left and middle dorsal and the right ventral ones. The ventricular epicardium involved up to 129 ganglia in humans and up to 198-in sheep. The largest number of the ventricular ganglionic cells in humans were located on the ventral side, in front of the conus arteriosus, while on sheep ventricles, the most numerous neurons distributed on the dorsal wall of the left ventricle. This comparative study of the morphological patterns of the human and sheep ventricles demonstrates that the sheep heart is neuroanatomically distinct from the human one and this must be taking into consideration using the sheep model for the heart physiology experiments.

The Secrets of the Frogs Heart.

The heart of the African clawed frog has a double-inlet and single-outlet ventricle supporting systemic and pulmonary circulations via a truncus, and a lifespan of 25-30years. We sought to understand the unique cardiac anatomic and physiologic characteristics, with balanced circulation and low metabolic rate, by comparing the basic anatomy structures with focused echocardiography and cardiac magnetic resonance imaging. Twenty-four adult female African clawed frogs were randomly subjected to anatomic dissection (n = 4), echocardiography (n = 10), and cardiac magnetic resonance (n = 10). All anatomical features were confirmed and compared with echocardiography and cardiac magnetic resonance imaging. The main characteristics of the cardiovascular circulation in frogs are the following: Intact interatrial septum, with two separate atrio-ventricular valves, preventing atrial mixing of oxygenated and desaturated blood. Single spongiform ventricular cavity, non-conducive for homogeneous mixing. Single outlet with a valve-like mobile spiral structure, actively streaming into systemic and pulmonary arteries. Intact interatrial septum, spongiform ventricle, and valve-like spiral in the conus arteriosus are likely responsible for balanced systemic and pulmonary circulation in frogs, in spite of double-inlet and single-outlet ventricle.

Anuran development: A reinvestigation of the conus arteriosus and gill formation in Bufo bufo throughout metamorphosis using micro-CT.

Using high‐resolution X‐ray micro‐CT imaging of whole Bufo bufo specimens, we acquired detailed 3D descriptions of the changing morphology of the cardiac outflow structures, in particular the conus arteriosus through larval development and the transition. Previous findings regarding anuran conal structures were contradictory, depending on the specifics of the 2D imaging methods used by different authors. Our descriptions of conal morphology at different developmental stages show that early tadpoles initially only have one opening at the ventricular‐conal junction and only one cavum within their conus; however, the forming septum coni soon divides the conus into two chambers, the cavum pulmocutaneum and the cavum aorticum. This is accompanied by the development of a second small opening at the ventricular‐conal junction. The separated chambers continue into the aortic arches. Following the aortic arches into the area where gills will form, we describe how blood vessels associated with the external gills develop from vessels arising from the truncus arteriosus. The external gills soon undergo partial absorption. During the transition from external to internal gills, the gill filaments retreat asymmetrically into a gill chamber formed by a hyoidal cover contacting the animal's ventral side, leaving only a single opening on the animal's left side, the opercular spout. B. bufo retains its internal gills up to metamorphic climax, with the aortic arches arising from the conus arteriosus still leading into the gills. Our 3D image data are publicly available and will provide a sound morphological basis for future studies.

The Evolution of The Cardiac Myosinome of Gnathostomes

The term myosinome has been recently coined to define the set and distribution of myosins in a particular tissue. Since different myosin isoforms have different contractile properties, the myosinome of cardiac fibers determines their type of contraction. Classically, it has been assumed that the cardiac myosinome of vertebrates is mainly formed by only two myosin heavy chain (MYH) isoforms, which are heterogeneously distributed in the heart: whereas MYH6 is more abundant in the inflow, MYH7 predominates in the outflow myocardium. However, this concept has been recently questioned after the identification of significant amounts of additional isomyosins in hearts of other vertebrates, i.e. MYH15 in the amphibian outflow myocardium; MYH2 and MYH7B in the inflow and outflow myocardia of chondrichthyans, respectively. To study the diversity and evolution of the cardiac myosinome in vertebrates, we have analyzed the inflow and outflow myocardia of representative specimens of polypteriforms, lepisosteiforms, acipenseriforms and dipnoi, by means of a specific myosin extraction method followed by quantitative proteomic analysis. We have identified five additional MYH isoforms (MYH1, MYH3, MYH4, MYH8 and Fast-skeletal MYH), each abundantly expressed in the inflow or outflow myocardia of distinct vertebrate groups, demonstrating that the cardiac myosinome in vertebrates is more diverse than initially thought. In general, the diversity of MYH isoforms has increased in most osteichthyes and decreased in teleosts and tetrapods. Therefore, not all vertebrates share the MYH6/MYH7 pattern observed in teleosts, birds and mammals, which can be considered a specialized vertebrate myosinome. In addition, the abundance and distribution of these MYH isoforms in the morpho-functionally diverse hearts studied allow raising several hypotheses on the evolution of the vertebrate cardiac myosinome: While MYH4 seems to be an autapomorphy of non-tetrapod sarcopterygians, MYH7B can be considered an ancient myosin, only present in hearts with a primitive anatomical design. The primitive type of cardiac contraction in gnathostomes with a linear heart anatomy and a long conus arteriosus might require the expression of MYH7B together with MYH1 and Fast-skeletal MYH. Cardiac MYH2 expression may have appeared in association with the development of a specialized cardiac conduction system, whereas that of MYH3 and MYH8 might be associated with adaptation to environments with low oxygen tension. Further studies are needed to confirm these hypotheses on the evolution of the cardiac myosinome, which constitutes a new research field on cardiovascular evolution.

Morphological Study of the Heart of the Indonesian Short-Nosed Fruit Bat (Cynopterus titthaecheilus)

Abstract. Rahma A, Hanadhita D, Prawira AY, Kasmono S, Maheshwari H, Satyaningtijas AS, Agungpriyono S. 2020. Morphological study of the heart of the Indonesian short-nosed fruit bat (Cynopterus titthaecheilus Temminck, 1825). Biodiversitas 21: 5094-5101. The energy demand of an animal becomes an important factor that affects the adaptation of cardiac or heart anatomy. As the largest Cynopterus bat in Indonesia, Cynopterus titthaecheilus (Temminck, 1825) is one of the flying mammals that need a lot of energy to accommodate its flying activity. This study aims to acknowledge the anatomical adaptation of the heart in C.titthaecheilus, which includes the weight ratio of the heart, heart structure, and primary blood vessel branches. This study conducted of 10 juvenile C. titthaecheilus (56.15±13.43 g), 13 females (74.38±10.34 g), and 18 males (73.27±13.54 g). Bats ware killed by ketamine overdoses, then the thoracic cavity was opened and the heart was removed from the thoracic cavity for observation. The results of this study revealed that the ratio of heart mass to body mass of adult female C. titthaecheilus was 0.014, male adult C. titthaecheilus was 0.015 and juvenile C. titthaecheilus was 0.015. The heart-shaped was an oval, located in the thoracic cavity, tilted to the left. On the other hand, the heart structure of C. titthaecheilus consisted of a thicker left ventricle compared to the right ventricle, but the musculi pectinati, musculus papillaris, and trabecula septomarginalis were well developed on the right side of the heart compared to the left side. Subsequently, the branches of the primary blood vessels in the heart consisted of an aortae ascendens, three arteria pulmonalis dextra and one arteria pulmonalis sinistra, a vena pulmonalis, the vena cava anterior dextra et sinistra, and a single vena cava posterior. In addition, the conus arteriosus, which is an enlarged space of the pulmonary artery, was observed in a large size. Based on this study, it was concluded that the heart structure of C. titthaecheilus was very important in supporting their ability to fly.

Histochemical characterization and connective fiber distribution of the cardiac outflow tract of pirarucu, Arapaima gigas (Schinz, 1822) (Osteoglossiformes, Arapaimidae)

The cardiac outflow tract (OFT) in teleosts is composed of a proximal short conus arteriosus and a distal well-developed bulbus arteriosus located between the ventricle and ventral aorta. The role of these anatomical components includes structural connections, prevention of blood backflow and blood pressure control, which are related to their histological and histochemical compositions. A previous study in the heart of the Amazonian species Arapaima gigas reported an unusual OFT arrangement among teleosts that has been found only in members of Osteoglossiformes so far. Thus, considering the wide structural variability of the teleostean OFT, the present study focuses on identifying glycosaminoglycans types and describing the distribution of collagen, elastic and reticular fibers in the conus arteriosus, conal valves, and bulbus arteriosus of A. gigas. Hearts from A. gigas between 327 and 4040 g weight were used. Collagen fibers were concentrated in regions that were regularly exposed to stress, as elastic fibers showed a broad distribution in all anatomical segments. Several fibrous connections between the conal valve leaflets and the conus arteriosus were observed, possibly acting as the primary connection form. The functions of the connective fibers in the valve leaflets and the bulbus are supported by an extracellular matrix rich in non-sulfated glycosaminoglycans. The complex reticular fiber network in the compact myocardium of the conus and the smooth muscle of the bulbus wall suggests a relevant role in support contraction of both muscle types, and in attachment and mobility of the conal valve leaflets.

Differential expression of myosin heavy chain isoforms in cardiac segments of gnathostome vertebrates\xa0and its evolutionary implications

BackgroundImmunohistochemical studies of hearts from the lesser spotted dogfish, Scyliorhinus canicula (Chondrichthyes) revealed that the pan-myosin heavy chain (pan-MyHC) antibody MF20 homogeneously labels all the myocardium, while the pan-MyHC antibody A4.1025 labels the myocardium of the inflow (sinus venosus and atrium) but not the outflow (ventricle and conus arteriosus) cardiac segments, as opposed to other vertebrates. We hypothesized that the conventional pattern of cardiac MyHC isoform distribution present in most vertebrates, i.e. MYH6 in the inflow and MYH7 in the outflow segments, has evolved from a primitive pattern that persists in Chondrichthyes. In order to test this hypothesis, we conducted protein detection techniques to identify the MyHC isoforms expressed in adult dogfish cardiac segments and to assess the pan-MyHC antibodies reactivity against the cardiac segments of representative species from different vertebrate groups.ResultsWestern and slot blot results confirmed the specificity of MF20 and A4.1025 for MyHC in dogfish and their differential reactivity against distinct myocardial segments. HPLC-ESI-MS/MS and ESI-Quadrupole-Orbitrap revealed abundance of MYH6 and MYH2 in the inflow and of MYH7 and MYH7B in the outflow segments. Immunoprecipitation showed higher affinity of A4.1025 for MYH2 and MYH6 than for MYH7 and almost no affinity for MYH7B. Immunohistochemistry showed that A4.1025 signals are restricted to the inflow myocardial segments of elasmobranchs, homogeneous in all myocardial segments of teleosts and acipenseriforms, and low in the ventricle of polypteriforms.ConclusionsThe cardiac inflow and outflow segments of the dogfish show predominance of fast- and slow-twitch MyHC isoforms respectively, what can be considered a synapomorphy of gnathostomes. The myocardium of the dogfish contains two isomyosins (MYH2 and MYH7B) not expressed in the adult heart of other vertebrates. We propose that these isomyosins lost their function in cardiac contraction during the evolution of gnathostomes, the later acquiring a regulatory role in myogenesis through its intronic miRNA. Loss of MYH2 and MYH7B expression in the heart possibly occurred before the origin of Osteichthyes, being the latter reacquired in polypteriforms. We raise the hypothesis that the slow tonic MYH7B facilitates the peristaltic contraction of the conus arteriosus of fish with a primitive cardiac anatomical design and of the vertebrate embryo.

Investigating the Echocardiography and Heart Anatomy of Immature Beluga (Huso huso)

Objective: The purpose of present study was to obtain a complete understanding about anatomical features and echocardiography of Beluga (Huso huso) species in order to provide standard approaches for performing echocardiography on this sturgeon species.Design - Experimental studyAnimals -10 immature (2.5 years old) Beluga (Huso huso)Procedures- To perform echocardiography, Sonosite-MicroMaxx ultrasonography Machin and Linear Probe with a frequency of 6-12 MHz of ventral approach between two pectoral fins were used.Results-Four main parts of the heart were identified in investigations and the way of locating and connections of these parts were examined. Sinus venosus had a thin wall and leaned toward left. The atrium wall was characterized by connective tissue and muscle. There was a valve structure between Sinus venosus and atrium. The ventricle had a thick muscular wall with a two-layer appearance. Conus arteriosus leaned toward right. This part had three rows of valves including one distal row and two proximal rows with a certain distance between the distal row and the two proximal rows.Conclusion and Clinical Relevance- Since there has not yet been a complete study on the heart of Beluga species in the terms of ultrasonography and anatomy, the present study can be utilized as a basis for investigating other sturgeon species. In the present study, a standard approach has been provided to perform echocardiography on Beluga species.

Proteomics analysis indicated the protein expression pattern related to the development of fetal conotruncal defects.

Abnormal development of embryonic conus arteriosus could lead to conotruncal defects in fetal heart, and increase the incidence of fetal congenital heart disease. Tetralogy of Fallot (TOF) is one of the most common forms of congenital heart disease. It may be helpful for us to solve this clinical problem through exploring the molecular mechanisms of development in embryonic congenital heart disease. Proteomics has attracted much attention in understanding the development of human diseases during the past decades. However, there is still little information about the relationship between protein expression pattern and TOF. In this study, we aimed to explore the potential linkage of proteomics and TOF development. Briefly, 121 differentially expressed proteins were identified from a TOF group, compared with a control group. The expression levels of 34 of these proteins were significantly different (>1.5 absolute fold change, p < 0.05) between the two groups. Gene ontology (GO) and pathway analysis showed that these proteins were mainly associated with carbon metabolism, biosynthesis of antibodies, positive regulation of transcription from RNA polymerase II promoter, nucleus, ATP binding, and so on. The ingenuity pathway analysis (IPA) results indicated that 435 of upstream regulators were identified of these differentially expressed proteins, which might be involved in the development of TOF. Data of string analysis showed the protein-protein interaction network among the differentially expressed proteins and regulators, which are related to TOF. In conclusion, our study explored the protein expression pattern of TOF, which might provide new insights into understanding the mechanism of TOF development and afford potential targets for TOF diagnosis and therapy.

The valves of the cardiac outflow tract of the starry ray, Raja asterias (Chondrichthyes; Rajiformes): Anatomical, histological and evolutionary aspects.

The cardiac outflow tract of chondrichthyans is composed of the myocardial conus arteriosus, equipped with valves at its luminal side, and the bulbus arteriosus devoid of myocardium. Knowledge of the histomorphology of the conal valves is scarce despite their importance in preventing blood backflow to the heart. Current information on the subject refers to a single shark species. The present report is the first to describe the structure of the conal valves of a batoid species, namely, Raja asterias. Hearts from seven starry rays were examined using scanning electron microscopy and histochemical techniques for light microscopy. In all hearts, the conus showed four transverse rows of three pocket-like valves each. Each valve was composed of a leaflet and its supporting sinus. The leaflet had a stout central body, rich in glycosaminoglycans, which contained fibroblasts, collagen and elastin. The central body was surrounded by two thin fibrous layers, outer and inner, formed mainly by collagen. The valves of the anterior row, which were the largest of the valvular system, were attached proximally to the conus arteriosus and distally to the bulbus arteriosus, and not to the ventral aorta as previously reported for chondrichthyans. The arrangement of the anterior valves in the starry ray is an anatomical pattern that apparently has been preserved throughout the evolution of vertebrates.

The artery of Mouchet: blood supply of the septomarginal trabecula in 50 human hearts.

The septomarginal trabecula is a muscular structure which transmits the right branch of the atrioventricular bundle. It is usually supplied by a branch from the second anterior septal artery. Anastomoses between the right and left coronary arteries may happen on the septomarginal trabecula. They are of great significance in order to prevent ischemia during a myocardial infarction. Surgeries such as Konno's and Ross' procedures implies in knowledge of these vessels anatomy. The coronary arteries of 50 human hearts were injected with latex and subsequentely dissected with the purpose of identifying the arterial branch that supplied the septomarginal trabecula. The trabecular branch arose from the second anterior septal artery in 38% of cases, and the branch arose from the first anterior septal artery in 26%. One of the hearts had its septomarginal trabecula supplied by the conus arteriosus arteryliterature. Anastomoses between the right and left coronary arteries were found inside the septomarginal trabecula. The right branch of the atrioventricular bundle is subject to a great number of clinical conditions and is often manipulated during surgery, thus, the study of the septal branches of the coronary arteries and the trabecular branch is essential.

Descrição anátomo-topográfica do coração da paca (Agouti paca)

Background : : : : The domestic animals heart is a conical hollow viscera, surrounded by pericardium, laterally compressed, accompanying the thorax shape. Atriums constituted the heart basis and their auricles partially bound the initial portion of the aorta and pulmonary trunk. In mammals, heart is kept suspended in the thoracic cavity and the pericardic sac is fixed dorsally by great veins and arteries roots, and ventrally fixed to the sternum, although its fixation to the diaphragm varies among species. This paper aimed to describe morphological aspects of the heart of the paca, the second biggest Brazilian rodent. Materials, Methods & Results : There were used 12 hearts of adult pacas for this study, obtained from the UNESP, Jaboticabal, SP, which died due fights or anesthesia during bandages or radiograph exams. The thoracic aorta was filled with colored latex and the animal was set in a 10% formaldehyde solution for at least 72 hours. The thoracic cavity was dissected and hearts individualized and measured with a paquimeter, lateromedially, craniocaudally and dorsoventrally. The paca heart is placed between the first and fifth intercostal space (ICS), in a craniocaudal oblique position; its basis is craniodorsally positioned, on the middle third between the first and second ICS and its apex is located near the sternodiaphragmatic joint, on the fifth ICS, tilted to the left antimere. The heart is surrounded by pericardium, which from ventrocaudally is originated the sternopericardic ligament, that continues as phrenopericardic ligament. At the heart basis, the rising of the pulmonary trunk was observed and the conus arteriosus formed a typical projection. The aorta also rised from the heart basis and its arch, which was caudally curved, crossed dorsally the pulmonary trunk; the right cranial and caudal cava veins drained to the right atrium. There is a left cranial cava vein, which surrounded the left atrium and joined the right caudal cava vein on the right atrium. The azygos vein joins the right cranial cava vein and four pulmonary veins drained to the left atrium. At palpation, a hard structure on the rising of the aorta was observed, similarly to a cartilaginous tissue, which would be part of the cardiac skeleton. The left and right coronary arteries were observed in all hearts. Discussion : The paca heart is anatomica and topographically similar to those of domestic mammals, differing from them for being placed one intercostal space more cranial and due to the presence of two cranial cava veins, the left and the right ones, besides the presence of the caudal cava vein. This vascular description is similar to that of small rodents, as rats and mice. In paca heart, the sinus venous, the terminal crest, the oval fossa, the atrioventricular valvae, the papillary muscles and tendinous cords, besides smooth atriums and auricles covered by pectinate muscles, were observed. The sternopericardic ligament, which is dorsally elongated as phrenopericardic ligament, is similar to the one present in humans, pigs, castors, and different from the one observed in carnivorous, that presents the phrenopericardic ligament and from the one of horses and ruminants, which present the sternopericardic ligament.

Anatomy of the coronary artery and cardiac vein in the quail ventricle: patterns are distinct from those in mouse and human hearts.

Coronary vessel development has been investigated in avian and mouse embryonic hearts. Quail embryos are a useful tool to examine vascular development, particularly because the QH1 antibody and transgenic quail line, Tg (tie1:H2B-eYFP), are useful to trace endothelial cells. However, there are only a few descriptions of the quail coronary vessels. Using ink injection coronary angiography, we examined the course of coronary vessels in the fetal quail heart. The major coronary arteries were the right and left septal arteries, which, respectively, branched off from the right and left coronary stems. The right septal artery ran posteriorly (dorsally) and penetrated the ventricular free wall to distribute to the posterior surface of the ventricles. The left septal artery ran anteriorly (ventrally) and penetrated the ventricular free wall to distribute to the anterior surface of the ventricles. The right and left circumflex arteries were directed posteriorly along the atrioventricular sulci. The cardiac veins consisted of three major tributaries: the middle, great, and anterior cardiac veins. The middle cardiac vein ascended along the posterior interventricular sulcus and emptied into the right atrium. The great cardiac vein ran along the anterior interventricular sulcus, entered the space between the left atrium and conus arteriosus and emptied into the right atrium behind the aortic bulb. The anterior cardiac vein drained the anterior surface of the right ventricle and connected to the anterior base of the right atrium. The course of coronary vessels in the quail heart was basically the same as that observed in chick but was different from those of mouse and human.

Chamber specific expression of Myosin heavy chain 7b in the heart of vertebrates

In extant vertebrates, myosin heavy chain (MyHC) 6 and 7 are the main isoforms of atrial and ventricular myocardium respectively, whereas MyHC7b has been proposed to be an ancient cardiac isoform only expressed during embryonic development in modern species. The MYHC7b DNA sequence has an intronic miRNA thought to be a regulator of slow‐twitch versus fast‐twitch muscle differentiation.The pan‐MyHC antibodies MF20 and A4.1025 are commonly used to highlight the myocardium in histomorphological studies. In preliminary immunohistochemical studies of the heart of the lesser spotted dogfish (Scyliorhinus canicula; Chondrichthyes), we have observed that while MF20 labels homogeneously all the myocardium, A4.1025 labels the inflow cardiac segments (sinus venosus and atrium) but not the outflow segments (ventricle and conus arteriosus). In order to interpret these results, we have performed western and slot blots from samples of dogfish and hamster (Mesocricetus auratus) hearts, HPLC‐ESI‐MS/MS from dogfish samples, and immunohistochemistry in hearts of representative species of vertebrates, namely elasmobranchs, polypteriforms, acipenseriforms, teleosts and mammals, using MF20 and A4.1025 antibodies.Western and slot blot results confirmed the specificity of MF20 and A4.1025 for MyHC in dogfish, as well as their differential reactivity against different myocardial segments. HPLC‐ESI‐MS/MS using protein databases from Callorhinchus milii (Chondrichthyes) and Chordata revealed the presence of MyHC6 and 7 in all the dogfish myocardial segments, and of MyHC7b only in the outflow segments. Immunohistochemistry showed that while MF20 signals were homogeneous in all the myocardial segments of all the species studied, A4.1025 signals were restricted to the inflow myocardial segments in elasmobranchs, homogeneous in teleosts and acipenseriforms, and low in the ventricle of polypteriforms.From our results it can be inferred that the A4.1025 antibody, as opposed to MF20, has a low affinity for MyHC7b, at least in the dogfish. In addition, we show that MyHC distribution in the cardiac chambers has changed during the evolution of gnathostomes. We raise the hypothesis that in early diverged groups of gnathostomes, MyHC6 and 7 were distributed in all the myocardial segments, whereas MyHC7b was specific for the outflow myocardium. In derived gnathostomes, MyHC6 and 7 became mainly restricted to the atrium and ventricle respectively, whereas MyHC7b disappeared from the heart, acquiring a regulatory role in cardiac and extracardiac myogenesis through its intronic miRNA.Support or Funding InformationThis study was supported by CGL2014‐52356‐P and FPU15/03209This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The anatomical components of the cardiac outflow tract of chondrichthyans and actinopterygians.

The outflow tract of the fish heart is the segment interposed between the ventricle and the ventral aorta. It holds the valves that prevent blood backflow from the gill vasculature to the ventricle. The anatomical composition, histological structure and evolutionary changes in the fish cardiac outflow tract have been under discussion for nearly two centuries and are still subject to debate. This paper offers a brief historical review of the main conceptions about the cardiac outflow tract components of chondrichthyans (cartilaginous fish) and actinopterygians (ray-finned fish) which have been put forward since the beginning of the nineteenth century up to the current day. We focus on the evolutionary origin of the outflow tract components and the changes to which they have been subject in the major extant groups of chondrichthyans and actinopterygians. In addition, an attempt is made to infer the primitive anatomical design of the heart of the gnathostomes (jawed vertebrates). Finally, several areas of further investigation are suggested. Recent work on fish heart morphology has shown that the cardiac outflow tract of chondrichthyans does not consist exclusively of the myocardial conus arteriosus as classically thought. A conus arteriosus and a bulbus arteriosus, devoid of myocardium and mainly composed of elastin and smooth muscle, are usually present in cartilaginous and ray-finned fish. This is consistent with the suggestion that both components coexisted from the onset of the gnathostome radiation. There is evidence that the conus arteriosus appeared in the agnathans. By contrast, the evolutionary origin of the bulbus is still unclear. It is almost certain that in all fish, both the conus and bulbus develop from the embryonic second heart field. We suggest herein that the primitive anatomical heart of the jawed vertebrates consisted of a sinus venosus containing the pacemaker tissue, an atrium possessing trabeculated myocardium, an atrioventricular region with compact myocardium which supported the atrioventricular valves, a ventricle composed of mixed myocardium, and an outflow tract consisting of a conus arteriosus, with compact myocardium in its wall and valves at its luminal side, and a non-myocardial bulbus arteriosus that connected the conus with the ventral aorta. Chondrichthyans have retained this basic anatomical design of the heart. In actinopterygians, the heart has been subject to notable changes during evolution. Among them, the following two should be highlighted: (i) a decrease in size of the conus in combination with a remarkable development of the bulbus, especially in teleosts; and (ii) loss of the myocardial compact layer of the ventricle in many teleost species.

The bulbus arteriosus of the holocephalan heart: gross anatomy, histomorphology, pigmentation, and evolutionary significance

This study was designed to determine whether the outflow tract of the holocephalan heart is composed of a myocardial conus arteriosus and a non-myocardial bulbus arteriosus, as is the case in elasmobranchs. This is a key issue to verify the hypothesis that these two anatomical components existed from the onset of the jawed vertebrate radiation. The Holocephali are the sister group of the elasmobranchs, sharing with them a common, still unknown Palaeozoic ancestor. The sample examined herein consisted of hearts from individuals of four species, two of them belonging to the Chimaeridae and the other two to the Rhinochimaeridae. In all specimens, the cardiac outflow tract consisted of a conus arteriosus, with myocardium in its walls and two rows of valves at its luminal side, and an intrapericardial bulbus arteriosus shorter than the conus and devoid of valves. The bulbus, mainly composed of elastin and smooth musculature, was covered by the epicardium and crossed longitudinally by coronary artery trunks. These findings give added support to the viewpoint that the outflow tract of the primitive heart of the gnathostomes was not composed of a single component, but two, the conus and the bulbus. All rabbitfish (Chimaera monstrosa) examined had pigment cells over the surface of the heart. The degree of pigmentation, which varied widely between individuals, was particularly intense in the cardiac outflow tract. Pigment cells also occurred in the bulbus arteriosus of one of the two hearts of the straightnose rabbitfish (Rhinochimaera atlantica) included in the study. The cells containing pigment, presumably derived from the neural crest, were located in the subepicardium.