bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atrioventricular node and input pathways: A correlated gross anatomical and histological study of the canine atrioventricular junctional region
Authors: Racker Darlene K. 
Published: February 2005

AbstractTo determine the architecture of the atrioventricular (AV) junctional region, structures in atrial preparations were correlated to those in serial sections made either parallel or perpendicular to the long axis of the AV node (AVN)/AV bundle complex. The results demonstrated the following for the first time: (1) A right medial atrial wall (MAW) extends anteriorly from the interatrial septum, superior to the interventricular septum (IVS). (2) An atrial interventricular septum (A‐IVS) groove is located between the base of the MAW and the crest of the IVS. (3) Three atrionodal bundles converge to form a proximal AV bundle (PAVB), which in turn is contiguous with the AVN. The atrionodal bundles are associated with the MAW or the superomedial and inferolateral margins of the coronory sinus. Terminal portions of the atrionodal bundles and the PAVB reside within the A‐IVS groove. The AV bundle was termed distal (DAVB) to avoid confusion. (4) The location of the AVN/DAVB complex topographically is deep to the apex of the septal cusp of the tricuspid valve subjacent to the MAW. Intracardially, the AVN/DAVB complex is within the central fibrous body. Significantly, this study resulted in the first unequivocal demonstration of discrete bundles of myocardial fibers associated with the atrial end of the AV node. Moreover, it appears likely that the atrionodal AV bundles are continuous with the sinoatrial nodal extensions, thereby forming internodal tracts.
Three‐dimensional reconstruction of the myofiber pattern in the fetal and neonatal mouse heart
Authors: McLean Miriam , Alison Ross M. , Prothero John 
Published: February 2005

AbstractA methodology for three‐dimensional reconstruction from serial sections and interactive computer graphics is described briefly. This methodology was applied to study the morphogenesis of the cardiac myofiber pattern in the fetal and neonatal mouse heart (ventricles). Few organized in‐plane myofibers were found in the myocardial wall before 12 days postconception, but many fibers were observed in the very numerous trabeculae at all times up to birth. However, beginning at about 12 days, the number of fibers in the myocardial wall increases rapidly: these are seen predominantly in the transverse plane. The neonatal mouse heart, especially the left ventricle, resembles a small adult muscular artery. But the global myofiber pattern in the mouse heart at these stages appears to be more complex than might be inferred from earlier studies of the local myofiber pattern at a few sites in the ventricles of a few species of adult mammals. In particular, the pattern in and adjacent to the interventricular septum appears quite complex.
Jaw movements and muscle activity during mastication in growing rabbits
Authors: Weijs Wim A. , Brugman Peter , Grimbergen Cees A. 
Published: February 2005

AbstractTo investigate the biomechanical effects of juvenile growth changes in the rabbit masticatory apparatus a comparison was made of mastication in just‐weaned and adult animals. Mandibular movements in two planes were registered by cineradiography. Masticatory muscle activity was recorded by finewire electromyography. The same pattern of unilateral mastication was present in the two ages. The most important changes in the jaw movements are (1) a decrease of jaw opening speed and chewing frequency and an increase in jaw opening time, (2) a decrease in maximum gape in soft food and an unaltered gape in small‐particle hard food, and (3) an increase in lateral jaw excursion, mainly due to a more pronounced movement of the jaw to the balancing side (lingual phase). The contraction patterns were basically similar in the two ages. The higher chewing frequency in young animals was attained by a larger degree of overlap between opening and closing muscle activities. Young animals used relatively more EMG activity to chew hay, the hardest food. The changes in opening speed, gape, and chewing frequency are consistent with earlier predictions from the morphological changes, and so is the extra activity needed to chew hard food. The increase in lateral excursion was not predicted. It is suggested to be caused by cheek teeth wear, making possible smooth occlusal guidance of the jaw at the balancing side. Some of the changes in juvenile morphology can be viewed as adaptations to a changing diet.
Deformation‐corrected computer‐aided three‐dimensional reconstruction of immunohistochemically stained organs: Application to the rat heart during early organogenesis
Authors: Laan Alfons C. , Lamers Wouter H. , Huijsmans Dionysius P. , Kortschot Anita Te , Smith Jerry , Strackee Jan , Los Jan A. 
Published: February 2005

AbstractThe application of a computer‐assisted, three‐dimensional reconstruction procedure for serial sections to embryonic rat hearts during the period of cardiac looping and compartmentation is described. The procedure relies on immunohistochemical staining for the introduction of selective contrast and on episcopic and diascopic images of each of the sections for alignment and correction of compression due to sectioning. Episcopic (reference) images are taken from the embedding block just before the cutting of a slice and are still aligned and undeformed. Diascopic images are taken from the sections after immunohistochemical processing and, hence, contain selective contrast but are deformed and no longer aligned. The three‐dimensional images are visualized as shaded voxel models.This approach allowed the unequivocal delineation of the developing myocardium and the inspection of its changing architecture both from the outside and from within. Furthermore, it allowed a quantification of myocardial volume. Because standardized and hence comparable views of three different stages were generated, changes in the shape of the cardiac loop, the atria, and the ventricles as well as changes in the position of the atrioventricular canal and interventricular foramen could be accurately described. Characteristic changes in the position of both the right ventricle and the atrioventricular canal that are essential for the formation of a correctly functioning four‐chambered heart could be observed. These changes in shape occur while the myocardial size increases dramatically.
Scanning electron microscope study of the morphology of the reptilian lung: The savanna monitor lizard varanus exanthematicus and the pancake tortoise malacochersus tornieri
Authors: Maina J. N. , Maloiy G. M. O. , Warui C. N. , Njogu E. K. , Kokwaro E. D. 
Published: February 2005

AbstractThe morphology of the langs of two reptilian species, Varanus exanthematicus and Malacochersus tornieri, have been studied on gross preparations, latex casts, and critical‐point‐dried tissues. The shape of these lungs was observed to conform with that of the body, the lung of the monitor lizard (Varanus) being long and ovoid while that of the pancake tortoise (Malacochersus) was rounded and laterally indented. With respect to the size distribution of the gas exchange compartments, the lungs were observed to be notably heterogenous. In both species these units were generally smaller in diameter in the cranial region of the lung while those in the caudal region were larger. The gas exchange compartments in the tortoise were more profusely compartemented with the primary, secondary, and tertiary septa being well developed white in the lizard only the primary and secondary septa were observed. The tertiary septa in the tortoise lung and the secondary septa in that of the monitor lizard defined the terminal gas exchange units, the favoli. The cast impressions closely resembled the actual lung tissue and convincingly revealed the hierarchical design of the gas exchange compartments as they radiate from the air chambers and ducts, terminally giving rise to the faveoli. This stratification clearly increases the surface area available for gas exchange in these lungs. Disparate refinements of the basic reptilian lung design, as noted here, may lead to differing anatomic pulmonary diffusing capacities for oxygen to which characteristics like energetics and mode of respiration in this taxon may be attributed.
Skeletal muscle in the diabetic mouse: Histochemical and morphometric analysis
Authors: Klueber Kathleen M. , Feczko John D. , Schmidt Gordon , Watkins John B. 
Published: February 2005

AbstractDespite the extensive literature concerning the neuropathy associated with diabetes, only limited information describes changes in the associated muscle. The objective of this study was to evaluate the histochemical and morphometric characteristics of diabetic muscle in the C57BL/KsJ db‐m strain of mouse. The histochemical analysis of myofiber type for the diabetic mouse revealed that the extensor digitorum longus muscle consisted of 53.1% type 2a, 46.0% type 2b, and 0.9% type 1 myofibers, a significant shift from the percentages found in the nondiabetic litter mates (44.4% type 2a, 55.6% type 2b, no type 1). Computer‐assisted morphometric analysis of myofiber size by fiber type indicated a significant difference in myofiber size for the type 2b fibers in muscles from diabetic mice. Similarly, there was a shift in the fiber size distribution to include a greater number of small type 2b myofibers when compared to controls. Skeletal muscle from diabetic mice exhibited a significant change in the percentage of fiber types, with an increase in the number of type 2a fibers, a fiber type grouping that implies possible denervation and reinnervation, and a decrease in myofiber size. These findings may explain why some diabetic patients complain of muscle weakness.
Influence of epithelial‐mesenchymal interaction on the viability of facial mesenchyme in vitro
Authors: Saber Georges M. , Parker Susan B. , Minkoff Robert 
Published: February 2005

AbstractSeparation and recombination experiments, employing a variety of tissue configurations in organ culture, were performed to determine the extent to which the epithelium of the maxillary process influences the viability of the underlying mesenchyme during organogenesis. The results of these studies indicated that the viability of mesenchyme of the maxillary process of early stage embryos was severely impaired when separated from the overlying epithelium. The influence of epithelium on the viability of mesenchyme was stage dependent; that is, the requirement for the presence of epithelium for the maintenance of the viability of mesenchyme became progressively less pronounced at older developmental stages. The response of mesenchyme to the presence of recombined epithelium resulted in the appearance of a delimited zone of influence extending, within specific boundaries, from the epithelial‐mesenchymal interface. Preliminary data from homotypic (maxillary epithelium‐maxillary mesenchyme), heterotypic (limb apical ectodermal ridge—maxillary mesenchyme) and heterochronic (stage 28 epithelium‐stage 22 mesenchyme) recombination experiments indicated that viability of mesenchyme could be achieved only through direct epithelial‐mesenchymal contact which allowed restoration of normal morphological relationships at the interface of the two tissues.
SEM characterization of a cellular layer separating blood vessels from endoderm in the quail embryo
Authors: Reiss Karen Z. , Noden Drew M. 
Published: February 2005

AbstractThe associations between the developing blood vessels and both endoderm and splanchnic mesoderm in quail embryos at stages 9–11 were examined by using scanning electron microscopy. Embryos were pinned ventral‐side up on agar plates and the endoderm was surgically removed prior to fixation and dehydration. This procedure exposes a netlike layer of cells closely apposed to the ventral surface of paraxial mesoderm and all visible blood vessels; we are calling this the subvascular layer. Development of this layer proceeds rostral‐to‐caudal, and lateral‐to‐medial, with the earliest stages of formation being visible over the unsegmented paraxial mesoderm of the segmental plate. The subvascular layer increases markedly in density slightly medial to the innermost boundary of the intraembryonic vascular plexus. Cells of this layer eventually establish a continuous sheet beneath the lateral plate and paraxial mesoderm and the notochord. With maturation, the cells of the subvascular layer approach confluence. The spatial and temporal patterns of development of the embryonic vascular tissues and the subvascular layer are closely correlated, suggesting a possible role for the subvascular layer in normal embryonic vascular development.
Use of nude (athymic) mice for the study of hypertrophic scars and keloids: Vascular continuity between mouse and implants
Authors: Ward Kischer C. , Sheridan Don , Pindur Jana 
Published: February 2005

AbstractHypertrophic scars and keloids appear to be unique to humans since animals are not known to form these lesions. Therefore, in an effort to develop an experimental model for their study, implants of these human lesions were made in nude (athymic) mice (nu/nu) in suprascapular subcutaneous pockets. The implants were recovered from 2 to 246 days. By histological and fine structural parameters all implants remained viable and their morphological character was maintained. Selected mice were injected with barium to confirm by microangiography vascular flow between mouse and implant. Hoechst stain for DNA, used to distinguish mouse cells from human cells, confirmed vascular anastamosis between host and implant: barium‐filled vessels in the interior of the implant demonstrated human endothelial cells. Peripheral vascularization of the implant with minimal ingrowth of mouse vessels occurs during the first 8 days. Anastamosis probably occurs sometime before 16 days postimplantation, or earlier, depending upon the availability of patent microvessels in the implanted tissue. The presence of the implant does not appear to prompt a continuing vascular growth into or throughout the implant. The time frame of 16 days postimplantation should be taken into account when developing schemata of experimental or therapeutic modalities.
Vestibular system of the newborn marsupial cat Dasyurus hallucatus
Authors: Gemmell R. T. , Nelson J. 
Published: February 2005

AbstractThe ultrastructure of the ear of the newborn native cat was examined to determine whether the vestibular system contained sensory receptors. A sensory region, presumably the utricle, was identified in each ear and consisted of a discrete population of otoliths overlying a sensory epithelium which possessed kinocilia and stereocilia. The remainder of the vestibular system did not appear to be developed anatomically. The newborn cat has rudimentary vestibular, olfactory, and mechanoreceptors (Merkel cells), and these structures may aid the newborn marsupial in the journey from the urogenital sinus to the pouch and in locating the teat.
Alteration of early vascular development after ablation of cranial neural crest
Authors: Bockman Dale E. , Redmond Mary E. , Kirby Margaret L. 
Published: February 2005

AbstractA previous study has shown that, subsequent to ablation of cranial neural crest, heart morphology and pharyngeal arch vessels (aortic arches) are altered before septation of the outflow tract normally occurs. In the present study, we concentrated on very early development of the aortic arch apparatus in the chick (incubation days 3–5). The three‐dimensional organization of the arch vessel apparatus was studied by scanning electron microscopy after intravascular injection of Mercox, and by serial sections of embryos embedded in plastic. Alterations in the arch vessel apparatus were already present by day three in embryos with neural crest ablation at stage 9–10. Bilateral symmetry frequently was lost. Arch vessels sometimes were enlarged and occupied most of the arch, with little surrounding mesenchyme. Some arch vessels were small or occluded. Mesenchyme was significantly reduced in quantity in the arches, and was not condensed and symmetrical as in controls. There was a significant increase in the proportion of direct apposition of vessel endothelium with epithelium, without the intervening mesenchyme typical of controls. The surgical manipulation used in this study leads to distinct alterations in the arches of components and relationships which are important in development. Altered blood flow likely affects the development of the heart.
Ultrastructural localization and identification of adrenergic and cholinergic nerve terminals in the olfactory mucosa
Authors: Zielinski Barbara S. , Getchell Marilyn L. , Wenokur Randall L. , Getchell Thomas V. 
Published: February 2005

AbstractPharmacological and ultrastructural methods were used to demonstrate alpha‐adrenergic regulation of secretory granule content of acinar cells of Bowman's glands and to localize and identify adrenergic and cholinergic axonal varicosities and terminals in the olfactory mucosa of the tiger salamander.The alpha‐adrenergic agonist phenylephrine caused secretory granule depletion from Bowman's glands; the alpha‐adrenergic antagonist phentolamine partially blocked this effect. These observations were quantified using light microscopic computer‐assisted morphometric techniques. Both drugs caused morphological signs of electrolye/water transport.Adrenergic axonal varicosities were identified by the presence of small granular vesicles (SGVs, 45–60 nm in diameter) containing electron‐dense material that was enhanced by 5‐hydroxydopamine loading and chromaffin reaction fixation techniques. Throughout the lamina propria, small fascicles with axons containing SGVs as well as varicosities and terminals with SGVs were located adjacent to blood vessels, Bowman's gland acini, and melanocytes. Mean vesicle diameters at these sites were 54 ± 7 nm, 50 = 9 nm, and 56 ± 8 nm, respectively; varicosities were located approximately 0.1–1.0 μm from their presumed cellular targets. Axonal varicosities containing small agranular vesicles (AGVs, 65 ± 8 nm in diameter), identified as cholinergic by their size and by the absence of electron‐dense material after 5‐hydroxydopamine loading and chromaffin reaction fixation, were located between adjacent acinar cells. In addition, adrenergic varicosities containing SGVs (56 ± 6 nm in diameter) were found within 1 μm of blood vessels associated with Bowman's gland ducts and sustentacular cells near the base of the olfactory epithelium.These results characterize the ultrastructural basis for adrenergic and cholinergic regulation of vasomotor tone and secretion within the olfactory mucosa.
Complex anomalies of the human aortic arch system: Unique case with both vertebral arteries as additional branches of the aortic arch
Authors: Schwarzacher Stephan W. , Krammer Eva B. 
Published: February 2005

AbstractWe describe a case of an aortic arch with five primary branches arising in a sequence that has previously never been reported. From right to left, the brachiocephalic trunk and left common carotid, left vertebral, and subclavian arteries originated from the convexity of the aortic arch. The last branch was the right vertebral artery that arose from the dorsal aspect of the aortic arch opposite the ligamentum arteriosum. Presenting a dilatation at its commencement, the right vertebral ran to the right behind the esophagus and entered the foramen transversarium of the seventh cervical vertebra, whereas the left vertebral passed to the foramen transversarium of the fifth cervical vertebra. The left vertebral artery gave off the left thyroid artery; a thyrocervical trunk was absent on the left side. A thyroidea ima arose from the brachiocephalic trunk. The embryology of this complex anomaly as well as its potential clinical significance are discussed.
Localization of serotonin‐like immunoreactivity in the merkel cells of pig snout skin
Authors: García‐Caballero T. , Gallego R. , Rosón E. , Basanta D. , Morel G. , Beiras A. 
Published: February 2005

AbstractThe presence of serotonin in the Merkel cells of pig snout epidermis was investigated by the peroxidase‐antiperoxidase immunohistochemical technique. Serotonin‐like immunoreactive Merkel cells were found in groups located at the base of epidermal rete pegs and in the external root sheath of sinus hair follicles (vibrissae). Immunoreactivity was stronger on the basal side of the Merkel cells, where dense‐cored granules are most numerous. Neither the nerve terminal associated with the Merkel cell nor the neighbouring epidermal cells were immunostained.These results are the first evidence of serotonin‐like immunoreactivity in mammalian Merkel cells. The fact that immunoreactivity is strongest in those parts of the Merkel cells with the highest granule density suggests that in these cells serotonin is probably localized in the dense‐cored granules.
Cytodifferentiation of two epithelial populations of the respiratory bronchiole during fetal lung development in the rhesus monkey
Authors: Tyler Nancy K. , Hyde Dallas M. , Hendrickx Andrew G. , Plopper Charles G. 
Published: February 2005

AbstractThis study describes the cytodifferentiation of the two populations of epithelial cells found in the respiratory bronchiole of the adult rhesus monkey. One population, pseudostratified and containing ciliated, nonciliated secretory, and basal cells, is found overlying the pulmonary artery (PA). The other population, not associated with the PA, contains nonciliated cuboidal cells between alveolar outpockets. In this study we used terminal conducting airways from the lungs of fetal (90 to 155 days gestational age [DGA]), postnatal, and adult rhesus monkeys. Ciliated cells were partially differentiated at 90 DGA (54% gestation) and completely differentiated by 134 DGA (80% gestation). Nonciliated secretory cells were partially differentiated at 95 DGA (57% gestation) but did not lose all glycogen until the postnatal period. Basal cells appeared by 134 DGA (80% gestation) and matured in the postnatal period. Small mucous granule cells appeared at 125 DGA (74% gestation) and did not change throughout fetal development. Neuroendocrine cells were present throughout the entire period studied. Nonciliated cuboidal bronchiolar cells of the nonciliated population of the respiratory bronchiole appeared at 105 DGA (62% gestation) and matured in the postnatal period. We conclude that 1) although most of the differentiation of the lower airway occurs before birth, most of the cell types are not completely differentiated at birth; 2) the sequence of differentiation for the cells of the ciliated pseudostratified epithelial population is ciliated, nonciliated secretory, and basal; 3) the sequence of differentiation for the nonciliated secretory cell is similar to that of the secretory cells in more proximal airways; and 4) basal, neuroendocrine, and small mucous granule cells are not a part of the differentiation sequence of the other cell types.