bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the hemopoietic microenvironment. III. Differences in the splenic microvascular system and stroma between Sl/Sld and W/Wv anemic mice
Authors: McCuskey Robert S. , Meineke Howard A. 
Published: February 2005

AbstractThe differences in the splenic microvascular system and stroma between Sl/Sld and W/Wv anemic mice were investigated using in vivo microscopic and histochemical methods. Spleens of Sl/Sld anemic mice had increased numbers of sinusoids containing blood flow and an increased concentration of sulfated acid mucopolysaccharide in the splenic stroma when compared to spleens of non‐anemic littermates; in both groups of mice the undifferentiated hemopoietic cells in the red pulp were enveloped with a coating of sulfated acid mucopolysaccharide. In contrast, in the W/Wv anemic mice, the number of sinusoids containing blood flow was one‐half of that seen in non‐anemic littermates. While the concentration of mucopolysaccharides in the splenic stroma of the W/Wv mice and their non‐anemic littermates appeared similar, the W/Wv mice had a deficiency in the number of undifferentiated hemopoietic cells in the red pulp as well as a deficiency in the number of such cells enveloped with a coating of sulfated acid mucopolysaccharide. Transfusion of the W/Wv mice with stem cells from non‐anemic littermates corrected the anemia. Blood flow through the sinusoids was restored to near normal levels, and the number of undifferentiated hemopoietic cells increased in the red pulp; most were enveloped with a coating of sulfated acid mucopolysaccharide.The histochemical results suggest specific defects in the composition of mucopolysaccharides in the hemopoietic microenvironment of Sl/Sld anemic mice and in the cell coatings of undifferentiated hemopoietic cells in W/Wv anemic mice. These results are consistent with our hypothesis that a cell coating of sulfated acid mucopolysaccharide is required for early erythroid differentiation but that a microenvironment which contains excessive concentrations of sulfated acid mucopolysaccharide is not conducive to supporting the later stages of erythroid development. In addition, the results obtained by in vivo microscopy of the microvascular system tend to support our hypothesis that erythropoietin‐sensitive stem cells respond to erythropoietin by producing a substance that is locally vasoactive.
Catecholamines and morphogenesis of the chick neural tube and notochord
Authors: Lawrence Irvin E. , Burden Hubert W. 
Published: February 2005

AbstractCatecholamines in the early chick embryo (days 2–3) were studied using the Falck‐Hillarp technique. After treating specimens with nor‐epinephrine, specific catecholamine fluorescence was localized in the early neural tube of the youngest embryos (stages 7–9). In older embryos (stages 10–12) exposed to exogenous norepinephrine the fluorescence was seen in both the neural tube and notochord and by stage 13 fluorescence was brighter in the notochord than neural tube. Endogenous notochord catecholamine fluorescence was demonstrable in stages 13 through 17 without exposure to exogenous amines although treatment with a monoamine oxidase inhibitor (nialamide) or norepinephrine intensified the fluorescence. Treatment of embryos with nialamide or an inhibitor of catecholamine synthesis (α‐Methyltyrosine) caused numerous archencephalic anomalies, ventral flexure of the head without lateral rotation, and spina bifida. The results suggest that catecholamines in the early neural tube and notochord may provide the motive force for morphogenetic movements, including closure of the neural folds and torsion of the embryo.
The functional anatomy and evolution of the mammalian humero‐ulnar articulation
Authors: Jenkins Farish A. 
Published: February 2005

AbstractMajor stages in the structural and functional evolution of the mammalian humero‐ulnar joint are described on the basis of paleontological and cineradiograhic evidence. In pelycosaurs (the earliest known fossil reptiles with mammalian affinities), the humerus projected laterad and more or less horizontally; locomotor movements were principally rotation about its proximodistal axis. Because the forearm moved in a plane perpendicular to this axis, the flexed elbow was subjected to substantial torque. The humero‐ulnar joint consisted of two pairs of facets that engaged upon humeral rotation and was principally a stabilizing rather than a flexion‐extension mechanism.Cynodonts (advanced mammal‐like reptiles ancestral to mammals) possessed an ulnar condyle rather than a trochlea. A condylar humero‐ulnar articulation, usually with a spiral configuration, was retained by early mammals and persists in slightly modified form among modern prototherians. The spiral joint allows the ulna to extend in a sagittal plane as the humerus rotates, adducts, and elevates.The primitive therian trochlea evolved by enlargement of the intercondylar groove separating the ulnar and radial condyles and by retention of part of the ulnar condyle mechanism. Cineradiography demonstrates the relationship of diverse types of mammalian humero‐ulnar joints to limb posture and excursion characteristics.
Effects of short‐term low intensity light on the albino rat retina. An electron microscopic study (1)
Authors: R. Shear Charles , Keith O'Steen W. , V. Anderson Kenneth 
Published: February 2005

AbstractRetinas of albino rats exposed to continuous, low intensity fluorescent light for periods of 6, 12, and 18 hr display fine structural changes in both pigment epithelial cells and in the outer segments of the photoreceptor cells. Adjacent pigment epithelial cells showed wide intercellular spacing (600 to 36,000 A) and retraction of the villous processes. As the rats were exposed to increasingly longer photoperiods, the lamellated discs, which are flattened in dark‐adapted retinas, became progressively more tubular.
A reexamination of the chorioallantoic placental membrane of a shrew, Blarina brevicauda: Resolution of a controversy
Authors: Wimsatt William A. , Enders Allen C. , Mossman Harland W. 
Published: February 2005

AbstractThe allantoic placenta of shrews has been classified as hemochorial, endotheliochorial and endothelioendothelial. Recent confusion has centered on the persistence of an intermediate cellular layer within the interhemal membrane and on its identity. Conflicting interpretations assert, (1) that the intermediate layer represents a continuous trophoblastic lamina (endotheliochorial placenta), or (2) that it consists of a discontinuous “maternal symplasma,” the trophoblast having disappeared early in development (endothelioendothelial placenta).Utilizing thin plastic sections for light microscopy and electron microscopy we find that the disputed intermediate layer comprises an exceedingly thin, but continuous layer of syncytiotrophoblast, and that the shrew placenta is indeed endotheliochorial. However, the interhemal membrane displays a most unusual organization. The trophoblast is sieve‐like in that it is honeycombed with interstitial (extracellular) spaces which open freely at both its surfaces. Into these channels project numerous processes of the maternal endothelium, and where these contact trophoblast close junctions are often apparent; in rare instances endothelial processes were seen to penetrate to the fetal surface of the trophoblast, but not through its well‐defined basal lamina. Maternal endothelium and trophoblast are separated by an irregular space filled with a dense amorphous material, but it lacks fibrillar components normally found in basal membrane. Peculiarities of the hypertrophied maternal endothelium include an abundance of oriented cytoplasmic fibrillar elements, moderate endoplasmic reticulum and ribosomes, and a marked alignment of mitochondria against the basal cell membrane. Hypertrophied fetal mesenchymal cells often intervene between the fetal endothelium and the rest of the interhemal membrane. Seldom does either abut directly against the basal lamina of the trophoblast; they are usually separated from it by a welter of cytoplasmic processes from both elements, which project into the fetal interstitial space. The fetal endothelial cells are somewhat hypertrophied, and their external processes, like those of the mesenchymal cells, often contain glycogen. Peculiarly, the fetal endothelium lacks a basal lamina. The mesenchymal cells display all the usual ultrastructural characteristics of protein synthesizing cells and appear highly active. Functional implications of the organizational peculiarities of the interhemal membrane are discussed.
Monoamine‐containing cell bodies in the squirrel monkey brain
Authors: Felten David L. , Laties Alan M. , Carpenter Malcolm B. 
Published: February 2005

AbstractFifteen catecholamine‐containing cell groups and eight indoleamine‐containing cell groups are present in the brain of the squirrel monkey. Most of the catecholamine‐containing cell groups (12) are similar to catecholamine‐containing cell groups previously described in the rat. However, three catecholamine‐containing cell groups not previously noted are found in the squirrel monkey brain.The indoleamine‐containing cell groups are found within, or adjacent to, the raphe nuclei. Differences between the localization of indoleamine‐containing cell bodies in the brain of the rat and the squirrel monkey are minor.
The systemic arterial pattern of the guinea pig: The head, thorax, and thoracic limb
Authors: Shively Michael J. , Stump John E. 
Published: February 2005

AbstractThe systemic arterial pattern of the guinea pig was studied to determine the arrangement of the major arterial trunks and their branches. Fifty‐nine specimens were examined by dissection, angiography, and corrosion casting. The arterial arrangement was found to resemble a typical mammalian pattern, although some exceptions were noted. For example, the internal carotid arteries were small and of questionable significance in the cerebral blood supply. Instead, a major portion of the blood supply to the brain appeared to be provided by the internal ophthalmic arteries. In the thoracic region, large dorsal scapular arteries originated and were distributed in part to the large fat pad in the dorsal cervical region. Also, each vertebral artery arose as two separate rami that anastomosed a few millimeters from their origin. The arterial pattern of the thoracic limb presented no unusual features.
The tectorial membrane of the rat
Authors: Ross Muriel D. 
Published: February 2005

AbstractHistochemical, x‐ray analytical and scanning and transmission electron microscopical procedures have been utilized to determine the chemical nature, physical appearance and attachments of the tectorial membrane in normal rats and to correlate these results with biochemical data on protein‐carbohydrate complexes. Additionally, pertinent histochemical and ultrastructural findings in chemically sympathectomized rats are considered. The results indicate that the tectorial membrane is a viscous, complex, colloid of glycoprotein(s) possessing some oriented molecules and an ionic composition different from either endolymph or perilymph. It is attached to the reticular laminar surface of the organ of Corti and to the tips of the outer hair cells; it is attached to and enclose the hairs of the inner hair cells. A fluid compartment may exist within the limbs of the “W” formed by the hairs on each outer hair cell surface. Present biochemical concepts of viscous glycoproteins suggest that they are polyelectrolytes interacting physically to form complex networks. They possess characteristics making them important in fluid and ion transport. Furthermore, the macromolecular configuration assumed by such polyelectrolytes is unstable and subject to change from stress or shifts in pH or ions. Thus, the attachments of the tectorial membrane to the hair cells may play an important role in the transduction process at the molecular level.
Scanning and transmission electron microscopy of the rat kidney
Authors: Bulger Ruth Ellen , Siegel Frances Lea , Pendergrass Robert 
Published: February 2005

AbstractThis study utilized scanning and transmission electron microscopy of renal tissue to provide new information on the gross and microscopic structure of the kidney. The luminal surface of the proximal convoluted tubule was characterized not only by the border of microvilli, but also by crater‐like depressions, and circumferential folds. In tissue processed for scanning electron microscopy the proximal tubular cells separated along their lateral surfaces clearly exposing the topography of the lateral cell projections of cytoplasm which have been generally unavailable for viewing because of their interdigitation with adjacent cells. The various segments of the nephron were identified on the basis of position in the kidney, general morphology, and the distribution and form of apical microvilli, cilia, or flaps. The external surface of the papillary tip had several parallel furrows into which the collecting ducts opened. Large plaquelike depressions lined the papillary surface. The opposed surface of the renal pelvis had small plaque‐like depressions separated by narrow ridges. Transmission electron microscopy of plastic‐embedded tissue specimens which had been previously dehydrated by the critical point drying method demonstrated that little damage occurred from this procedure.
Ultrastructure of encapsulated nerve endings in rat gingiva
Authors: Marrtinez I. Richardo , Pekarthy James M. 
Published: February 2005

AbstractThe ultrastructure of a specialized encapsulated nerve ending located in the papillary layer of rat gingiva is described. The axon in the corpuscular ending possesses microvesicles and microtubules, and is surrounded by laminar cells (with basement membrane) and capsular cells (modified fibroblasts, no basement membrane).
The fine structure of developing unit collagenous fibrils in the chick
Authors: Morse Dennis E. , Low Frank N. 
Published: February 2005

AbstractPerivertebral cervical connective tissue was taken from chick embryos of incubation ages from 72 hours through hatching and from 4, 8, 12, and 16 week old chicks. Preparations for electron microscopy were routine except for en bloc staining with 5% aqueous uranyl acetate. Collagenase digestions of thin sections confirmed the presence of tropocollagen in banded extracellular fibrils.Banding becomes demonstrable in fibrils at about seven days but repeating units cannot be measured. Close to connective tissue cells the banded material is present in wide sheets. Partially banded fibrils (250 Å wide) physically related to microfibrils are present in acellular regions. Growth in fibril diameter is slow through the second week (up to 300 Å) but increases nearly 200 Å on days 14 and 15. Fibrils larger than 500 Å resist uranium and lead staining following the period of accelerated growth. Smaller fibrils (< 500 Å) continue to stain well. A basic banding pattern of measurable periodicity is established by the eighth day. This consists of a major doublet, two minor doublets, and two singlets. The intraperiod distance does not change significantly with growth (510 Å average). Additional bands near the first minor doublet and singlets of the basic pattern are first clearly demonstrable at 14 and 15 days. Ambiguities in banding and period length are believed to be due to plane of section, interference with detail by other fibrils and flaky amorphous material or possibly to differential shrinkage along the length of a single fibril.
Cortical granules in artificially activated (parthenogenetic) rabbit eggs
Authors: Gulyas Bela J. 
Published: February 2005

AbstractThe fate of cortical granules was ascertained in cold‐shock activated rabbit eggs. Unfertilized oocytes were obtained 14 hours after intravenous injection of Human Chorionic Gonadotropin. Experimental oocytes were stored at 6 to 10°C for 24 hours in F10 medium containing 10% rabbit serum. Control oocytes, and the experimental ones subsequent to cold‐shock treatment, were incubated for 24 hours. Formation of ‘pronuclei’ occurred in 6% of the cold‐shock treated oocytes. None of the control oocytes were activated. Electron microscopic observations show that activation occurred without the dehiscence of cortical granule content into the perivitelline space. Cortical granules were dispersed in the cytoplasm or clumped together at the periphery. Occasionally, cortical granules were found discharged into the perivitelline space with the limiting membrane intact.
The postnatal development of the human temporomandibular joint
Authors: Wright Donald M. , Moffett Benjamin C. 
Published: February 2005

AbstractFifty‐one temporomandibular joints (24 male, 27 female) obtained at autopsy were used in the study. Forty‐four specimens were younger than ten years while others ranged to 21 years. These joints were radiographed, sectioned sagittally or frontally, and slide‐mounted as decalcified and undecalcified sections using conventional histologic techniques. The slides were examined microscopically in whole, polarized, and ultraviolet light. Two of the specimens surveyed exhibited fluorescent labeling as a consequence of therapeutic tetra cycline application.Throughout the postnatal developmental period the articular tissue and disc consist of fibrous connective tissue. Cartilage cells were not observed in these structures at any time during the twenty‐one year age‐span studied. At birth the disc is flat and develops an accentuated S‐shaped profile as the articular tubercle develops.The articular tubercle is only a small elevation at birth and is formed by a combination of endochondral, immature, and ordinary intramembranous bone formation. The characteristic profile of the temporal portion of the joint is achieved during the first two or three years of life, after which gradual enlargement and compaction of bony structures occur.While the mandibular condyle grows in a constant posterior, superior, and lateral direction, it does not attain its mature contour until the late mixed dentition age. Condylar growth cartilage is approximately 1.5 mm thick at birth but it thins down in a short time to about 0.5 mm. During the first two years of life the growth cartilage is penetrated by vascularized connective tissue septa whose function appears to be nourishment of the cartilage. The growth cartilage does not show the columnar arrangement of chondrocytes seen in epiphyses, nor are isogenous groups observed. At 16 to 17 years, the growth cartilage becomes thinner and a closing plate of bone is beginning to coalesce below it.
An analysis of the human femur
Authors: Lavelle Christopher L. B. 
Published: February 2005

AbstractNineteen linear and three angular dimensions were measured for 590 left femurs derived from Bronze‐Age to present‐day population samples. Univariate analysis showed varying patterns of contrast between the populations, depending upon which femoral dimension was compared. Similarly, multivariate analysis also provided varying patterns of contrast between the populations, depending upon which group of dimensions was included in the analysis. Following standardization of the femoral linear dimensions against the maximum femoral length, in contrast, repeat multivariate analyses showed a progression from the Bronze‐Age to the present‐day samples, although there was only limited discrimination between the samples.
Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine III. Entero‐endocrine cells
Authors: Cheng Hazel , Leblond C. P. 
Published: February 2005

AbstractThe origin, differentiation and renewal of entero‐endocrine cells was examined in the duodenum, jejunum and ileum of the mouse using light and electron microscopic radioautography after a single injection or continuous infusion of 3H‐thymidine. When s‐collidine buffered glutaraldehyde was used for fixation prior to electron microscopic study, all granules in all entero‐endocrine cells were spheroidal and, therefore, their shape could not be used to classify the cells into subgroups, as done after fixation in phosphate buffered aldehyde. Thus, the cells were all considered as belonging in a single family.In the light microscope, mitosis is not observed in the entero‐endocrine cells identified by iron hematoxylin staining. However, under the electron microscope, a few cells that contain a small number of characteristic granules, some filament bundles and many free ribosomes are in division or are labeled one hour after an injection of 3H‐thymidine. These cells are interpreted as young entero‐endocrine cells. They are located in the crypt base. They resemble crypt‐base columnar cells and are, therefore, suspected of arising from them.Differentiation may be examined by following the fate of the young enteroendocrine cells which are labeled by 3H‐thymidine. Within the crypts, these cells acquire a gradually increasing number of granules while losing the ability to divide. The few granules initially present usually have a particulate content and may include a small dense core; but, as differentiation proceeds and granules accumulate, their content is mostly dense and homogeneous. The differentiation of precursor cells into mature entero‐endocrine cells takes about two days.Meanwhile, in the same manner as columnar and mucous cells, enteroendocrine cells migrate up the crypt, reach the villus and are lost at the extrusion zone.The turnover time of entero‐endocrine cells is estimated to be 3.9 days in duodenum and 4.0 days in jejunum.
A degeneration study of some habenular efferents to the midbrain in a wallaby
Authors: Way John S. 
Published: February 2005

AbstractIn this study, specimens of both sexes of a Western Australian wallaby (Setonix brachyurus) had surgical or electrolytic lesions made in the habenular complex unilaterally. Thirty‐five‐micron sections, cut coronally and parasagitally, were stained by the Nauta‐Gygax ('54) or the Fink‐Heimer ('67) technique to demonstrate degenerating fibers. Degeneration was seen in the habenular commissure and bilaterally in the habenula and fasciculus retroflexus, but was most extensive ipsilaterally. Habenular fibers destined for the tegmentum and central gray passed caudally into the midbrain in a continuous fan‐like array which extended from the central gray dorsally to the interpeduncular nucleus ventrally. In their posterior course some fibers crossed the midline with the decussating cerebellar fibers. The majority of fibers, with those in the fasciculus retroflexus which passed ventral to the decussation of the superior cerebellar peduncle, turned dorsally. They passed mostly just lateral to the midline nuclei and into the central gray where degeneration was seen throughout the entire extent. Terminal degeneration was seen in the interpeduncular nucleus primarily in the dorsal and posterior parts, in the ventral tegmental nucleus and throughout the central gray, but was more densely clustered in the region of the dorsal tegmental nucleus.