bluuebunny/crossref_metadata_2025_split huggingface dataset:
Baroreflex mediated control of heart rate and vascular capacitance in trout
Authors: Sandblom E. , Axelsson M. 
Published: March 2005

SUMMARYThe baroreflex was triggered by altering branchial blood pressure with pre-and post-branchial occlusions for 30 s in rainbow trout Oncorhynchus mykiss. The cardiac limb of the baroreflex was monitored by continuous heart rate (fH) measurements. Responses of venous capacitance vessels were assessed, immediately following either occlusion, by measuring mean circulatory filling pressure (MCFP). Arterial responses were evaluated as the change in dorsal aortic blood pressure(Pda) before and after pre-branchial occlusion. In untreated fish pre-branchial occlusion resulted in tachycardia(62.4±2.4 to 69.1±1.7 beats min–1), decreased venous capacitance reflected as an increase in MCFP (0.17±0.03 to 0.27±0.03 kPa) and increased Pda (4.0±0.2 kPa compared to 3.2±0.1 kPa before occlusion). Post-branchial occlusion somewhat reversed the responses since fH decreased(62.4±2.4 to 53.0±3.1 beats min–1), whereas MCFP remained unaltered. Treatment with the α-adrenergic blocker prazosin (1 mg kg–1) increased resting MCFP to 0.33±0.03 kPa and appeared to abolish both venous and arterial responses to branchial occlusion. Subsequent atropine treatment (1.2 mg kg–1) abolished all chronotropic responses. We present for the first time ample evidence for baroreflex-mediated control of cardiovascular homeostasis, including both the chronotropic and the vascular limb of the baroreflex in an unanaesthetized fish. Furthermore, a novel technique to cannulate and occlude the dorsal aorta, using a Fogarty thru-lumen embolectomy catheter, is explained.
Complete dysraphism in 14 somite human embryo. A contribution to normal and abnormal morphogenesis
Authors: Dekaban A. S. , Bartelmez G. W. 
Published: February 2005

AbstractThe youngest completely dysraphic human embryo of 2.75 mm G.L. has been reconstructed from the microscopic sections and studied in detail. Although the neural folds failed to close throughout the dorsal extent of this 14 somite embryo, the beginning of independent closure took place rostrally at the torus opticus. The last feature has been shown to be the usual event in normal embryos of this stage. Careful examination of other structures than the nervous system reveals only minor abnormalities. Thus, the dispersion of cells of somites I and II as well as loosening of other sclerotomes in this region has begun prematurely. On the other hand, some retardation in the development of the pharynx, heart and nephros has been noted. Specifically, the chorda, the mesenchyme, blood vessels and gut have been found to be normal.The literature pertaining to the closure of the neural folds has been discussed. Also, the reports on experimental inhibition of the formation of the neural tube are discussed with special emphasis on the work of Davis ('42).Davis, J. O. 1942 Photochemical spectral analysis of neural tube formation. University of Missouri, Doctor' thesis.
The available evidence refutes the contention that the closure of neural folds is induced by adjacent structures of whatever derivation. It appears plausible as Davis demonstrated in his experiments that certain biochemical reactions within the neural epithelium may be involved in the process of normal closure of the neural folds.Morphological findings in the present embryo do not support most of the previously advanced theories relating to the pathogenesis of dysraphic states.
The anatomy of the arterial supply to the cranial regions of the sheep and ox
Authors: Baldwin B. A. 
Published: February 2005

AbstractBy means of neoprene latex injected preparations, the anatomy of the arterial supply to the brain has been determined in the sheep and ox. In these two ruminant species, blood destined for the Circle of Willis and thence the brain must first pass through a well‐developed intra‐cranial carotid rete. The main source of blood supply to the carotid rete in the sheep is from the external carotid artery, via branches of the internal maxillary artery.In both the sheep and the ox, the internal carotid artery is poorly developed in the young animal and the portion proximal to the carotid rete is absent in the adult. The internal carotid artery, in animals of all ages, can be traced through the rete to emerge as the efferent vessel, which divides to form the Circle of Willis.In the ox, the main source of blood supply to the intra‐cranial carotid rete is the external carotid artery, via branches of the internal maxillary, but, in addition, the rete communicates directly with the vertebral arteries by way of the basi‐occipital arterial plexus.Unlike most other species, the basilar artery in both sheep and ox has only tenuous connections with the vertebrals. In both species, the basilar artery tapers caudally and is continued as the ventral spinal artery. The basilar can therefore be regarded as a caudally directed branch of the Circle of Willis in both these animals. A well‐developed occipito‐vertebral anastomosis is a marked feature of the cephalic circulation in both sheep and ox.
Articular remodeling in the adult human temporomandibular joint
Authors: Moffett Benjamin C. , Johnson Lent C. , McCabe James B. , Askew Harold C. 
Published: February 2005

AbstractArticular cartilage can proliferate sufficiently to alter the contours of joints, allowing them to adapt morphologically to various mechanical stresses. This remodeling has been classified into three types based on histologic criteria which were then applied to the temporomandibular joint. This joint has a fibrous type of articular tissue which is converted postnatally into fibrocartilage in the loaded areas. The thickness and cell population of this tissue, and the amount of internal reconstruction in the subchondral bone vary from one part of the joint to another. These changes appear related to the distribution of mechanical stresses in the joint. Conclusions drawn are: The temporomandibular joint shows the following remodeling trends: progressive remodeling on the anterior part of the condyle, medial part of the tubercle, and roof of the mandibular fossa; regressive remodeling on the posterior part of the condyle and on the lateral part of the tubercle. A perforation in the disc causes progressive remodeling on the condyle and regressive remodeling on the tubercle at the perforation site. Articular remodeling merges gradually into osteoarthritis as the articular tissue breaks down. The net effect of remodeling that has become uncompensated or pathologic is: condyle flattened and enlarged, tubercle resorbed, disc perforated, and articular surfaces uneven. If the dentition is not restored or replaced, a high rate of temporomandibular remodeling occurs which will probably continue into osteoarthritis.
Ultrastructure of bovine spermatozoa. I. The head of normal, ejaculated sperm
Authors: Saacke R. G. , Almquist J. O. 
Published: February 2005

AbstractThe ultrastructure of the normal bovine sperm head has been studied and particular attention has been given to the morphology and coverings of the nucleus and the formation of the equatorial segment.The bovine sperm head consists of a homogeneous, flattened nucleus which is covered anteriorly by a three‐layered head cap and posteriorly by a loose, thin, dense, post‐nuclear cap. The nucleus measures approximately 0.2 to 0.3 μ in thickness. It tapers anteriorly to a sharp point along the frontal portion of the head and thickens posteriorly to accommodate an implantation socket for the tail. The nuclear membrane is double and porous. Vacuoles or openings of variable size and shape are present in the nucleoplasm, predominantly in the posterior portion of the nucleus. The head cap measures approximately 350 to 500 Å in thickness. It consists of dense inner and outer membranes which envelop a moderately electron dense middle layer. The head cap thickens across the frontal part of the head forming a ridge on one side of the nucleus.A sequence of structural alterations in the head cap provide evidence for the appearance of the equatorial segment. The anterior portion of the head cap swells and deteriorates leaving the posterior portion intact as a band about the center of the nucleus. This band represents the equatorial segment.
Persistent stunting following x‐irradiation of the fetus
Authors: Rugh Roberts , Duhamel Lyse , Osborne Alan W. , Varma A. 
Published: February 2005

AbstractCFl female mice were time mated and the embryos at each gestation day from 0.0 to 18.0 were x‐rayed to 100 r and the young carried to four months at which time a skeletal study was made. With this exposure the litters were reduced in size, following irradiation at certain gestation ages, and there was neo‐natal mortality so that this skeletal study is based upon the survivors to four months and represents the maximum development under the conditions of irradiation. The sex ratio was not altered by this irradiation. Male mice of this strain are always heavier than the females of the same age, and this exposure reduced the over‐all average of either sex by 2.5 grams. The skeletal measurements were taken from 1,005 radiographs of the living animals, and the averages calculated for each gestation day. There were sex differences in stunting, even when x‐irradiation occurred before day 9.0. When the differences were pronounced the female was the more adversely affected. The highest statistical significance in skeletal effects of seven measurements was between 11 and 13 days, when the embryo shows the earliest skeletal differentiation. Such mice were topographically well developed.
Studies on the nerve endings in the heart
Authors: Miller Malcolm R. , Kasahara Michiko 
Published: February 2005

AbstractThe hearts of dogs, cats, monkeys and lambs were studied by methylene blue perfusion and/or immersion. The principle types of sensory nerve terminals found in these hearts were end‐nets and complex unencapsulated endings. End‐nets are formed by the anastomoses of the branched dendrites of several apparently different myelinated fibers. Complex unencapsulated endings are discrete much branched endings of medium to large sized fibers and vary greatly in form and size.The epicardium is supplied mainly with complex unencapsulated endings of highly variable form. End‐nets are rare in this location.No sensory endings were demonstrated in the myocardium. Motor terminals in the form of fine unmyelinated nerve fibers were demonstrated on both atrial and ventricular myocardial muscle fibers.The atrial endocardium, particularly in the areas of the openings of the great vessels and on the interatrial septum is the best innervated area of the heart. Endnets, and a wide variety of complex unencapsulated nerve endings occur singly and in combination in these areas.The ventricular endocardium is supplied only with end‐nets.The tricuspid and mitral valve leaflets have both end‐nets and complex unencapsulated endings while the aortic and pulmonary valve leaflets have only end‐nets.The cardiac complex unencapsulated nerve endings (baroreceptors) are morphologically and functionally homologous to complex unencapsulated nerve endings (“stretch” receptors) in other areas of the organism.The detailed structure and function of the end‐net terminals remain undetermined.
Structural and functional aspects of rodent salivary glands including two desert species
Authors: Shackleford John M. , Schneyer Charlotte A. 
Published: February 2005

AbstractThe submaxillary glands of the adult desert rat, antelope squirrel, rat, mouse and hamster have in common low levels of amylolytic enzyme in comparison with the relatively high levels of parotid gland amylase in these rodents. Submaxillary gland acini are classed as seromucous secreting although there is some variation in the carbohydrate histochemistry of these secreting units. Granular tubules are absent in antelope squirrel submaxillary glands and they are present in the submaxillary glands of the desert rat, rat, mouse and hamster. Electron micrographs reveal the presence of numerous basal folds in the acini of antelope squirrel submaxillary and parotid glands. These structures were not observed in the salivary gland acini of the hamster. Golgi membranes and “immature” secretion granules are topographically intimate in parotid glands of the hamster and antelope squirrel. In the submaxillary glands of these two rodents, the secretory material appears to originate in relation to the endoplasmic reticulum and secondarily, the granules become associated with a diffusely arranged system of Golgi membranes. The sublingual glands of all the rodents of this study are predominantly ones that produce mucous secretion and contain well developed striated duct systems. Of the salivary glands investigated in this study, the parotid glands of the rat, mouse and desert rat produce an isotonic saliva; the saliva of the other glands is definitely hypotonic.
Morphological and histochemical observations on trophoblast and decidua of the basal plate of the human placenta at term
Authors: Dallenbach‐Hellweg G. , Nette G. 
Published: February 2005

AbstractThe trophoblastic cells of the basal plate at the end of pregnancy still have an important hormonal function, in contrast to the decidual cells which appear to exert their main function at the onset of pregnancy. Possibly the decidual cells are functionally replaced by the basal trophoblastic cells, which phagocytize and destroy them. Although both types of cells are structurally quite similar and appear to produce the same hormones, but at different times, genetically they are very different. They degenerate morphologically in much the same way, but the cause for the retrogressive change for each is distinct. The trophoblastic cells degenerate with reticulum‐fibrinoid inclusions which they have mainly phagocytized. The decidual cells perish with collagen inclusions formed from collagen fibers they in turn produced.
Placentation in the spotted hyena (Crocuta crocuta Erxleben), with particular reference to the circulation
Authors: Wynn Ralph M. , Amoroso E. C. 
Published: February 2005

AbstractA study of the placenta of the spotted hyena (Crocuta crocuta Erxleben), based on five specimens from early in the second third of pregnancy to full term, is presented. Resembling the dog and cat in the retention to term of a large allantois and a medium‐sized yolk sac, the hyena is unique among Carnivora in the possession of a hemochorial villous placenta, allied structurally more to that of New World monkeys than to the other carnivores. The intimacy of the fetal and maternal circulations is further increased by so‐called intraepithelial capillaries in the syncytial trophoblast. The hyena, unlike most carnivores, possesses no central hematoma or marginal deposit of pigment, and lacks specialized structures in the chorionic membrane. The cytotrophoblast, however, does undergo modifications associated with phagocytosis of histotrophe in the paraplacental regions and in the junctional zone of the placenta proper.The principal mode of entry of maternal blood is directly into the subchorial sinus, into which uterine arteries, carried up in a crescent of gestational endometrial tissue at the margin of the placenta, empty. Smaller arteries reach the subchorial sinus in maternal septa that traverse the entire trophoblastic zone. Major arteries do not discharge blood at the base of the placenta, but basal drainage constitutes the sole means of return of blood to the uterine veins. The phylogenetic significance of the morphogenesis and vasculature of the placenta of Crocuta is discussed.
The enzyme histochemistry of the osteoclasts of normal and “ia” rats
Authors: Handelman Chester S. , Morse Anna , Irving James T. 
Published: February 2005

AbstractEnzymes involved in oxidative metabolism as well as acid phosphatase were studied histochemically in osteoclasts from newborn normal rats and their littermates who suffered from a generalized defect in bone resorption (the “ia” rat). The osteoclasts of normal rats demonstrated intense activity for DPNH and TPNH diaphorase as well as succinic, malic and lactic dehydrogenase. Isocitric and glutamic dehydrogenase were less than one‐half as active but no less definite. In the “ia” rat the reaction for the diaphorases and dehydrogenases were exactly as observed in the normal. Acid phosphatase was observed in normal osteoclasts as a general cytoplasmic reaction and also in a band of concentrated activity at the junction of the cell and bone. The osteoclasts from “ia” animals had greater acid phosphatase activity (more than twice as reactive) than the normal. However, the “junctional band” was only rarely observed in this anomaly. The junctional band may represent sites into which enzymes such as acid phosphatase are secreted in the resorption process and therefore only associated with active osteoclasts. It is possible that the “ia” rat may successfully form but not secrete the enzyme.
An electron microscopic study of the cementum, Sharpey's fibers and periodontal ligament in the rat incisor
Authors: Stern Irving B. 
Published: February 2005

AbstractThe rat incisor is a continuously erupting, so‐called “rootless,” tooth. It differs from human or similar “rooted” teeth in that its generative cells persist at the base of the tooth. These cells are derived from the invagination of oral epithelium which forms the dental lamina and the developing dental organ. This epithelium becomes a vase‐shaped structure surrounding a condensation of connective tissue elements called the dental papilla. The cells on the labial aspect of the epithelial dental organ specialize to form enamel. The cells on the lateral and lingual aspects remain undifferentiated and are called Hertwig's epithelial sheath. The odontoblasts are derived from the dental papilla. The hard tissues of the tooth form continuously at the base, and the tooth erupts into the oral cavity where the incisal edge is worn by abrasive action during gnawing (v. Brunn, 1887; Addison and Appleton, '15; Schour and Massler, '42).Hertwig's sheath extends from the base of the tooth to a short distance beyond the point where dentin formation commences. At this level the epithelial cells separate and the sheath disintegrates. As these cells separate, cementoblasts and collagen fibers appear adjacent to the newly forming dentinal surface. Apatite crystals are deposited in the matrix of collagen fibers and a thin layer of cementum results (Selvig, '63). Since Hertwig's sheath is persistent at the base of the tooth, this initial phase of cementogenesis is continuous.In rooted teeth, on the other hand, initial cementogenesis is completed when the root becomes fully formed, and Hertwig's sheath has been expended. There may be subsequent progressing depositions of cementum to form one or several strata. This initial stratum is called “primary cementum” and the successive layers are called “secondary cementum.” Primary cementum contains fine fibrils arranged radially (fiber cementum). Secondary cementum generally contains cells (osteocementum) but it may be acellular. Regardless of category, cementum contains matrix (intrinsic) fibers, and also, in most cases, Sharpey's (extrinsic) fibers (Lehner and Plenk, '36; Egli, '46; Held, '51; Schmid, '51; Sicher, '62).During the course of eruption of the rat incisor, the periodontal fibers which are attached to the cementum move with the tooth until they somehow undergo dissolution prior to the entry of the tooth into the oral cavity. A similar picture is obtained during the more limited period of eruption of rooted teeth. The mechanisms of formation, reorganization and dissolution of the periodontal fibers are all matters of biologic importance. Moreover, investigations of these phenomena may have some bearing upon understanding those pathologic processes which involve the detachment of the gingiva from teeth and the exfoliation of teeth from their sockets.
Histochemical studies on seromucous‐ and mucoussecreting cells of human salivary glands
Authors: Munger Bryce L. 
Published: February 2005

AbstractHuman salivary and lacrimal glands have been studied with a variety of methods to demonstrate polysaccharides in tissue section. On the basis of these studies, an attempt has been made to clarify the classification of exocrine cells. Serous cells secrete proteinaceous material without significant polysaccharide in the secretory granules such as the pancreatic acinar cell and gastric chief cell. Seromucous cells secrete a watery product, but the secretory granules contain variable amounts of mucopolysaccharide in the secretory granule. Typical seromucous cells are found in the parotid gland, lacrimal gland, submaxillary gland and eccrine sweat glands. Mucous cells liberate a viscous product rich in mucopolysaccharide. The typical mucous cell is the intestinal goblet cell. Other examples are the mucous portion of the submaxillary gland, the entire sublingual gland, bronchial gland, and Brunner's gland. Human pancreatic acinar and gastric chief cells are unique as compared to other species since the secretory granules of these cells, usually considered to be serous, contain a small amount of neutral mucopolysaccharide.
Origin and development of lens cataracts in mumps‐infected chick embryos
Authors: Robertson G. Gordon , Williamson Alice P. , Blattner Russell J. 
Published: February 2005

AbstractCritical inocula of Enders strain of mumps virus were injected over the blastoderm at 36, 48, 60, 72 and 96 hours of incubation (37°C). Surviving embryos were harvested at daily intervals up to 14 days postinoculation.Gross and microscopic observations revealed the lens to be the only organ consistently exhibiting abnormal development following inoculation with mumps virus. By comparison, maldevelopment in other structures was occasionally observed up to the third day postinoculation, but rarely in embryos surviving three or more days. Characteristic lens cataracts were observed, but only in embryos which had been inoculated prior to Hamburger‐Hamilton stage 18, i.e., prior to separation of the lens vesicle from surface ectoderm.An analysis of the histopathogenesis of lens cataracts in embryos inoculated at stages 8–17 indicates that the differentiating lens fibers became progressively more extensively damaged as development proceeded. However, it is evident that the differentiation of new lens fibers proceeded peripherally as the more mature fibers continued to be destroyed centrally. It can be concluded that differentiating lens fibers are highly susceptible to damage by mumps virus, but the initiation of the characteristic defect occurred in our experiments only during the early formative phases of lens development.