bluuebunny/crossref_metadata_2025_split huggingface dataset:
The autoradiographic demonstration of estrogen binding in normal human cervix and vagina during the menstrual cycle, pregnacy, and the menopause
Authors: Gould Stanley F. , Shannon John M. , Cunha Gerald R. 
Published: February 2005

AbstractUsing the technique of in vitro steroid autoradiography, the localization and modulation of nuclear estrogen binding sites has been studied in normal human cervix and vagina during the menstrual cycle, pregnancy, and the menopause. Marked differences occur in nuclear estrogen binding between these two organs. Nuclear estrogen binding varies throughout the menstrual cycle in the vaginal epithelium, whereas vaginal stromal cells consistently exhibit nuclear estrogen binding throughout the cycle. In contrast, the cervical squamous and columnar epithelia show much less cyclic variability in nuclear estrogen binding sites. As in the vagina, the cervical stroma consistently binds estrogen. High levels of nuclear estrogen binding sites are found in the vagina of the postmenopausal patient, and lower levels of binding occur postpartum. The implications of these localizations, with special reference to the role of the cervical and vaginal stroma, are discussed.
Chronobiology: Anatomy in time
Authors: Pauly John E. 
Published: February 2005

AbstractChronobiology is that branch of science that objectively explos and quantifies mechanisms of biological time structure, including the important rhythmic manifestations of life. It is the study of biological rhythms. This paper introduces chronobiology and some of its vocabulary, principles, and techniques.A circadian rhythm is a regularly repetitive, quantitative physiological change with a period of about 24 hr (20–28), but the spectrum of rhythms includes those with periods less than 20 hr (ultradian) and longer than 28 hr (infradian). These rhythms are ubiquitous among the eukaryotes, innate and endogenous; their periods are precisely controlled by synchronizers in the environment. Rhythms can be manipulated by altering their synchronizers or by introducing more dominant ones. When organisms are removed from their environment and placed in constant conditions, rhythms revert to their natural frequencies and free‐run. All of an organism's rhythms operate simultaneously, but their peaks and troughs do not necessarily occur at the same time.There are rhythms in susceptibility to drugs; a fixed dose may have a therapeutic effect at one point along the 24 hr time scale and a harmful one at another. Knowledge of these rhythms can be important when designing experimental or treatment protocols and interpreting results. Examples are provided to show that single‐time‐point sampling can lead to erroneous results, unless biological periodicity is taken into consideration.
Chronobiology at the cellular and molecular levels: Models and mechanisms for circadian timekeeping
Authors: Edmunds Leland N. 
Published: February 2005

AbstractThis review considers cellular chronobiology and examines, at least in a superficial way, several classes of models and mechanisms that have been proposed for circadian rhythmicity and some of the experimental approaches that have appeared to be most productive. After a brief discussion of temporal organization and the metabolic, epigenetic, and circadian time domains, the general properties of circadian rhythms are enumerated. A survey of independent oscillations in isolated organs, tissues, and cells is followed by a review of selected circadian rhythms in eukaryotic microorganisms, with particular emphasis placed on the rhythm of cell division in the algal flagellate Euglena as a model system illustrating temporal differentiation. In the ensuing section, experimental approaches to circadian clock mechanisms are considered. The dissection of the clock by the use of chemical inhibitors is illustrated for the rhythm of bioluminescence in the marine dinoflagellate Gonyaulax and for the rhythm of photosynthetic capacity in the unicellular green alga Acetabularia. Alternatively, genetic analysis of circadian oscillators is considered in the green alga Chlamydomonas and in the bread mold Neurospora, both of which have yielded clock mutants and mutants having biochemical lesions that exhibit altered clock properties. On the basis of the evidence generated by these experimental approaches, several classes of biochemical and molecular models for circadian clocks have been proposed. These include strictly molecular models, feedback loop (network) models, transcriptional (tape‐reading) models, and membrane models; some of their key elements and predictions are discussed. Finally, a number of general unsolved problems at the cellular level are briefly mentioned: cell cycle interfaces, the evolution of circadian rhythmicity, the possibility of multiple cellular oscillators, chrono‐pharmacology and chronotherapy, and cell‐cycle clocks in development and aging.
Quo vadis basic and clinical chronobiology: Promise for health maintenance
Authors: Halberg Franz 
Published: February 2005

AbstractChronobiology is the eminently interdisciplinary science of interactions in time among metabolic, hormonal, and neuronal networks. It involves anatomy, biochemistry, microbiology, physiology, and pharmacology, at the molecular, intracellular, intercellular, and still higher levels of organization. The compounds coordinating a time structure‐–proteins, steroids, and amino‐acid derivatives–provide for the scheduling of interactions among membrane, cytoplasmic, and nuclear events in a network involving rhythmic enzyme reactions and other intracellular mechanisms. The integrated temporal features of the processes of induction, repression, transcription, and translation of gene expression remain to be mapped in relation to the available framework, consisting of the sequences of phospholipid and RNA labeling, DNA formation, and mitosis, to delineate a circadian cell cycle upon which further hormonal and neural coordination acts (Halberg et al., 1959a,b, 1979a). There is a need for communication over temporal as well as spatial distances among different specialized structures devoted, in individuals, to metabolism, growth, reproduction, and the ability to adjust, and, in species, to the capacity to adapt. For a better understanding at all levels of behavior in its broader sense of organization in time, chronobiology requires familiarity with temporal aspects of metabolism, hormones, and neurons. In other words, broadly trained, full‐time “general practitioners” of a chronobiology in its own right are needed.
The differentiation of the dermis in the laboratory mouse
Authors: Van Exan Robert J. , Hardy Margaret H. 
Published: February 2005

AbstractThe purpose of this study was to provide a comprehensive and sequential account of the differentiation of the dermis in one body region in a mammalian species. A histological, histochemical, and ultrastructural study was made of each cellular and matrix component of the dermis of the upper lip of the mouse during prenatal development. On the basis of these observations, the development of the dermis was divided into four phases: I) undifferentiated mesenchyme (12, 13 days), II) cell differentiation (14, 15 days), III) dynamic transition (16 days), and IV) matrix differentiation (beginning at 17 days). The first phase was marked by a decrease in the cell density but no change in the ultrastructure of the undifferentiated mesenchyme cells. The second phase began with the cytodifferentiation of the mesenchyme cells and was characterized by the appearance of new cell types in the dermis (immature fibroblasts, mast cells, myoblasts, and cells of indeterminate type). During phase III the dermis was undergoing rapid change. Fibroblasts became fully differentiated, mast cell density reached a sharp peak, there was a marked increase in the number of collagen fibrils in the dermal matrix and the first collagen fibers were observed, and changes occurred in the pattern of proteoglycan synthesis. Aggregations of vesicles appeared to be extruded from cytoplasmic blebs on the fibroblasts in large quantities at this time. Further differentiation of the dermal intercellular matrix occurred during the fourth phase, which continued after birth, as more collagen was laid down to form the connective tissue stroma.
Anatomy and vasculature of a minke whale heart
Authors: Ochrymowych Christina , Lambertsen Richard H. 
Published: February 2005

AbstractThe heart from a 4‐m‐long minke whale (Balaenoptera acutorostrata) was studied to determine the details of its anatomy and to consider cardiac adaptations to diving. The volume fraction (Vvc) of capillaries in the wall of the left ventricle was determined at different levels from base to apex and at different depths from epi‐ to endocardium using a light microscopic stereologic technique. Typical of cetaceans, this minke whale heart was distinctly flattened dorsoventrally. A moderator band, characteristic of ungulate hearts, spanned the right ventricle. The right and left atrioventricular valves were tricuspid and bicuspid, respectively. The right coronary artery supplied the dorsal and right lateral myocardium. The left coronary artery supplied the ventral and left lateral myocardium. An anastomosis between the dorsal and ventral interventricular arteries occurred in the dorsal interventricular groove. Stereologically, a decreasing transmural gradient in Vvc was identified between the epicardium and the subepicardium at 15 cm from the apex. Our results, however, did not reveal any significant deviations in the pattern of capillary distribution in the wall of the left ventricle between this baleen whale and terrestrial mammals. Measurements of the heart, great vessels, coronary vasculature, and ventricular walls are also given, and they suggest a physiologic and adaptive right ventricular hypertrophy. Based on these and other observations, we propose that the relatively great thickness of the right ventricle and the distinctive shape of the cetacean heart are adaptations to the hemodynamic changes and collapse of the thorax associated with apneic diving.
Functional anatomy of the peripheral olfactory system of the african lungfish Protopterus annectens owen: Macroscopic, microscopic, and morphometric aspects
Authors: Derivot Jacques H. 
Published: February 2005

AbstractAn anatomical functional study of the olfactory system of Protopterus annectens along the course of the primary olfactory neuron was made by means of macroscopic and microscopic methods on samples of specimens weighing from 3 to 1.250 gm. The olfactory organ, opening by anterior and posterior nostrils into the oral cavity, may be considered a macrosmatic fish type according to the repartition of receptor areas along parallel grooves and on the basis of its active irrigation mechanism. A morphometric study of Protopterus, using a set of seven specimens weighing from 4 to 350 gm, is compared with two morphometric studies on Silurid fishes and reveals some original features concerning the increase of the surface area of the receptor epithelium. The olfactory organ is meant to function in water; its isolation from the aerial environment is carried out by closing the apertures with edema linked to the hypothyroid and cholinergic crisis during the starvation stage; it represents an adaptation to the life in a special environment. This study does not support the assimilation of the posterior intrabuccal opening to a choana, nor the presence of a functional vomeronasal organ. The olfactory nerve shows a definite degree of organization, but it was not possible to recognize any vomeronasal nerve linked with the former. The histological organization of the bulbar relay is of a primitive type; it was impossible to locate an accessory olfactory bulb corresponding to a functional vomeronasal organ, the presence and the innervation of which by the nervus terminalis is discussed.
A light and electron microscopic study of osteodentin formation in the rat incisor after adriamycin administration
Authors: Karim Algernon C. , Eddy Ertrice L. 
Published: February 2005

AbstractThe effect of adriamycin (10 mg/kg body weight) on the rat incisor was investigated in 8‐day‐old animals at 9 days and 14 days after subcutaneous injection. The drug produced changes that were still present 14 days after administration. During this time osteodentin formation, which appeared to be the principal effect of the drug on the incisors, occurred to such an extent that in some regions of the teeth the pulp chamber was almost completely occluded. The formation of osteodentin began at the periphery of the pulp and gradually advanced towards the central region. Moreover, in some sections of the incisor the dentin layer was greatly reduced to a thin superficial layer, while osteodentin surrounded most of the pulp chamber. Cells that appeared to be differentiated pulp‐mesenchymal cells were found within as well as on the surface of the irregular osteodentin matrix. Since this drug has been used in the treatment of childhood osteosarcomas, the possibility of dental abnormalities developing in these children cannot be overlooked.
Ultrastructural localization of lectin receptors on the bone‐marrow sinusoidal endothelium of the rat
Authors: Pino Richard M. 
Published: February 2005

AbstractThe bone‐marrowThe hyphenation of bone‐marrow preceeding sinusoids or endothelium in this paper is in accordance with the style required by The American Journal of Anatomy. R.M.P
sinusoidal endothelium is a cellular bar‐rierthat separates developing blood cells in the extravascular space from the peripheral circulation. Mature blood elements enter the circulation via transendothelial migration pores. In the present study, monosaccharide constituents on the bone marrow endothelium were examined using lectin‐affinity cytochemistry. With lectin‐horseradish and lectin‐ferritin conjugates, mannosyl, N‐acetylglucosaminyl, galactosyl, N‐acetylgalactosaminyl, and sialic acid were localized to the luminal plasmalemma, bristle‐coated pits and diaphragmed fenestrae. These were conspicuously reduced on the abluminal plasmalemma. When the tissue was treated with biotinylated lectins followed by avidin‐ferritin, only a localization with wheat‐germ agglutinin (sialic acid; N‐acetylglucosaminyl) was observed. Pretreatment of the bone marrow with neuraminidase enabled the localization of the other monosaccharide components by the biotin‐avidin method. Accumulations of carbohydrate residues were identified near the endothelium subjacent to migrating cells. Fucosyl moieties marked by Ulex europaeus agglutinin (UEA) reagents on the endothelium were not present. All binding was abolished by incubation of tissue and lectin conjugates with specific hapten sugars. Labeling was also not present after Pronase E treatment, indicating that the identified monosac‐charides are components of glycoproteins rather than glycolipids. The possible function of endothelial‐surface glycoproteins as receptors for the surfaces of mature blood cells and their role in transmural migration are discussed.
Injury to nerves and the initiation of amphibian limb regeneration
Authors: Mescher Anthony L. 
Published: February 2005

AbstractThe possibility has been investigated that nerves, which promote mitotic activity during the growth phase of limb regeneration, may also release factors upon injury to stimulate the cellular events during the initiation of regeneration. These events have been compared in control, innervated limb stumps and in limbs denervated for various periods before amputation. Wound closure occurred in an essentially normal manner in limbs denervated at the time of amputation but frequently occurred at reduced rates or not at all in limb stumps denervated 5 days before amputation. Tissue loss and various degrees of morphological regression were seen in many of the predenervated limb stumps, including all of those denervated for 6 days or more before amputation. Evidence is presented which suggests that regression may result from a combination of the denervated state and disturbance to the limb ' vascular system. Limbs predenervated 2‐10 days before amputation were fixed 7 days after amputation and examined histologically. All limb stumps, including those involved in regression, showed tissue dissociation and cellular dedifferentiation. Autoradiography revealed that the dedifferentiation involved DNA synthesis in both denervated and innervated limbs. Seven days after amputation, DNA‐labeling indices in limb stumps predenervated 2 or 4 days were similar to those of control limbs, but labeling indices were significantly reduced in limbs predenervated 6 or more days. The results are assessed in light of the state of nerve degeneration in the limbs at the time of amputation and are discussed in terms of what is known regarding nerve‐derived growth‐promoting substances.
A radioautographic study of the incorporation of iron 55 by the ameloblasts in the zone of maturation of rat incisors
Authors: Karim A. , Warshawsky H. 
Published: February 2005

AbstractThis study was designed to study the time course of the incorporation of 55Fe into the ameloblasts of maturation in rat incisors. Male Sherman rats (100 ± 5 gm) were injected intravenously with 0.9 mCi of 55Fe and sacrificed in pairs by perfusion at various time intervals from 5 min to 7 days after injection. The incisors were demineralized in 4.13% disodium EDTA, postfixed in 1% osmium tetroxide in veronal acetate buffer, and embedded in Epon. Incisors from control rats injected with only physiological saline were treated in the same way. Sections from blocks of tissue in the zone of maturation were prepared for light microscope radioautographic observations. The greatest incorporation of iron occurred at 9 mm within the zone, at this site the ameloblasts contained few pigment granules. About 5 mm deeper into the zone the activity fell off to zero, as observed at 2.5 hr after injection of 55Fe. Between 1 day and 7 days after injection the 55Fe labeling was found over the cells containing many pigment granules, while the initial labeling over the cells within 9 mm of the zone had diminished. These data have shown that at any given time, from 30 min to 4 hr, the iron enters the maturation ameloblasts over a wide extent of the zone, reaching a maximum at about 9 mm from the onset of maturation. However, at longer times (1 day to 7 days) the labeling curve shifts and shows the greatest activity beyond 9 mm within the zone.
The development of the spleen in the Australian lungfish, Neoceratodus forsteri Krefft, with special reference to its relationship to the “gastro”‐enteric vasculature
Authors: Saito Hiroaki 
Published: February 2005

AbstractThe spleen of Neoceratodus forsteri Krefft grows in the shape of a “boomerang” on the left lateral‐dorsal‐right lateral part of the borderline between the foregut and the yolkgut. Development of the spleen follows the following stages: (1) appearance of the splenic primordium as a mesenchymal condensation in a limited portion of the region supplied by the third and fourth vitelline arteries on both sides, (2) development of the splenic sinuses within the primordium, (3) formation of the “gastric” and enteric splenic portal systems and (4) growth of the spleen along the anterior extremity of the spiral valve. The blood vascular dynamics of the foregut and the yolkgut are intimately involved with the formation of the spleen in this species. These processes were, therefore, compared with similar processes in other animals, and the characteristics of this organ common to vertebrates were investigated.
Histological and ultrastructural studies of secondary neurulation in mouse embryos
Authors: Schoenwolf Gary C. 
Published: February 2005

AbstractThe histological and ultrastructural features of secondary neurulation in C57BL/6 mouse embryos were examined as a first step in the analysis of how this process occurs in mammalian embryos. Secondary neurulation involves two major events in mouse embryos: (1) formation of the medullary rosette (9.5‐ to 10‐day embryos) or plate (11‐ to 12‐day embryos), and (2) cavitation. These two events occur simultaneously. The medullary rosette consists of elongated tail bud cells, radially arranged around a central lumen formed by cavitation. The secondary portion of the neural tube forms in 9.5‐ to 10‐day embryos by progressive enlargement of the central lumen and addition (by cell recruitment or mitosis) of tail bud cells to the rosette. The medullary plate likewise consists of elongated tail bud cells, but these cells do not surround a central cavity. Instead, cells of the medullary plate extend ventrad from the basal aspect of the dorsal surface ectoderm to a slit‐like cavity formed by cavitation. Formation of the secondary neural tube occurs in 11‐ to 12‐day embryos, principally by the recruitment of more lateral and ventral tail bud cells into the medullary plate. Free cells and cellular debris are frequently encountered in the forming lumen of the secondary neural tube, but cells exhibiting signs of necrosis were absent in cavitating regions. Numerous small intercellular junctions form at the inner (juxtaluminal) ends of tail bud cells as the medullary rosette or plate is forming and cavitation is occurring. These observations suggest that cavitation per se (i.e., formation of a lumen) during secondary neurulation is a relatively passive phenomenon, which results principally from neighboring cells becoming polarized apicobasally and incorporated into a primitive neuroepithelium. The latter constitutes the walls of the forming secondary neural tube.
Cartilage in the atlantic hagfish, Myxine glutinosa
Authors: Wright Glenda M. , Keeley Fred W. , Youson John H. , Babineau Donna L. 
Published: February 2005

AbstractLight and electron microscopic observations and biochemical analysis of the lingual cartilages from the Atlantic hagfish, Myxine glutinosa, reveal two different types of cartilage, designated types 1 and 2, respectively. The anterior and medial lingual are type 1, while the posterior lingual cartilage is type 2. Chondrocytes in type 1 cartilage are similar to those found in other vertebrate cartilages. The presence within the Golgi elements of material that resembles a component of the extracellular matrix suggests the involvement of active chondrocytes in the synthesis of the matrix. The matrix of the type 1 cartilage contains fibrils arranged to form concentric lamellae in the territorial matrix and irregularly arranged, branched fibrils in the interterritorial matrix. Biochemical analysis of the type 1 cartilage reveals that it is composed primarily of a cyanogen bromide (CNBr)‐insoluble protein of unique composition that we have termed “myxinin.” Myxinin appears to be similar, but not identical, to lamprin. Type 2 cartilage bears no resemblance to any other known vertebrate cartilage. The principal cells are hypertrophied and are characterized by masses of cytoplasmic filaments. The appearance of the organelles in smaller nest cells suggests that nest cells are active in the production of some of the matrix, which consists primarily of collagen. Microfibrils and a basal lamina‐like material are also present. Biochemical analysis of the type 2 cartilage reveals that the CNBr‐insoluble material is different from myxinin. Comparisons of lamprey and hagfish cartilages prompt the concept that these two agnathans probably followed long‐independent evolutionary histories.