bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative cell changes and vascularisation in the early corpus luteum of the pregnant rat
Authors: Meyer Geoffrey T. , Bruce Neville W. 
Published: February 2005

AbstractEarly corpora lutea (CL) of the rat were histologically examined on Day 1, 2, 4, and 6 of gestation. Measurements were taken of total volume and of the number of luteal and endothelial cells in one CL of both ovaries of five rats at each stage examined. CL volume increased over the 6 days from ‐‐0.76 to 1.39μl and peripheral plasma progesterone levels from 8.1 to 33.2 ng/ml. The number of luteal cells per CL (range 303,000 to 37,000) did not significantly change, and there was no evidence of mitosis or death amongst these cells. Luteal cell volume increased from 1.74 to 3.49 pl and nuclear volume from 0.25 to 0.38 pl, the former being the major cause of CL growth. The CL appeared to be richly vascularized, even on Day 1, and the number of endothelial cells per CL (range 289,000 to 354,000) remained relatively constant over the period examined.It was concluded that the number of luteal cells per CL is determined prior to or around ovulation in the rat and that subsequent growth of the CL is due to hypertrophy and not hyperplasia.
Tridimensional study of the deep cortex of the rat lymph node. III. Morphology of the deep cortex units
Authors: Bélisle C. , Sainte‐Marie G. 
Published: February 2005

AbstractRecently we reported that the deep cortex of the rat lymph node is made up of semi‐rounded “units,” some of which are partially fused into “complexes”. We further found that each unit is centered on the opening(s) of an afferent lymphatic vessel, the topographical organization of the deep cortex of a node correlating with the distribution pattern of the opening(s) of its afferent lymphatic(s). The present study aims to clarify the morphology of the deep cortex unit, particularly with regard to its reticular framework, its lymphatic sinuses, as well as its network of postcapillay venules. For that purpose, we analyzed rat nodes from various locations by way of tridimensional reconstruction. The observations revealed that each unit is formed of a “center” and a “periphery,” distinguishable from one another on the basis of their morphological features. The center is nearly devoid of reticular fibers, whereas the periphery exhibits a dense framework of fibers. Moreover, the periphery is the site of concentration of most postcapillary venules of a unit and contains lymphatic sinuses which, peculiarly, are often loaded with small lymphocytes. While both regions are populated mainly by small lymphocytes, the periphery usually contains a lower concentration of these cells than the center. The overall findings support the view that the center is a site of cellular retention and proliferation, whereas the periphery is a site of rapid lymphocyte migration in and out of the unit.
Tridimensional study of the deep cortex of the rat lymph node. IV. Differential labelling of the deep cortex units with 3H‐uridine
Authors: Sainte‐Marie G. , Peng F.‐S. , Bélisle C. 
Published: February 2005

AbstractUsing tridimensional reconstruction, it was recently found that the deep cortex of rat lymph nodes comprises one to several basic “units”. Each unit is a semi‐rounded structure contiguous to the peripheral cortex and bulging into the medulla of a node. Other investigators reported that transfused lymphocytes, heavily labelled in vitro by 3H‐uridine, became concentrated in an illdefined region of nodes, referred to as the mid and deep cortex. This suggested to us that the in vivo labelling of nodes with 3H‐uridine, might allow to further characterize the units on a physiological basis. Therefore, rats were injected intraveously with a dose of 1–20 μCi of 3H‐uridine/gm body weight and sacrificed 1 hour to 3 days later. The radioautographs of their nodes were exposed up to 535 days. The observations revealed that a large dose of 3H‐uridine combined with a long exposure of the radioautographs yielded a differntial labelling of the cell population of the units, characterized by a much more intense reaction than that of the surrounding structures. This demonstrated that the physiology of the lymphocyte population of the deep cortex units differs from the morphologically similar lymphocyte population of the extrafollicular zone of the peripheral cortex. The possible reason(s) for the differential labelling of the units is discussed.
Unusually complex basement membranes in the midgut of two decapod crustaceans, the stone crab (Menippe mercenaria) and the lobster (Homarus americanus)
Authors: Factor Jan Robert 
Published: February 2005

AbstractUltrastructural studies of the stone crab (Menippe mercenaria) and the lobster (Homarus americanus) demonstrate that the basement membrane of the midgut (intestine) is unusually complex. In both species, the basement membrane is three‐layered and has processes that form extensive networks protruding into the connective tissue. The possible functional significance of this complex structure is discussed.
The origin of the epicardium and the embryonic myocardial circulation in the mouse
Authors: Viragh Szabolcs , Challice Cyril E. 
Published: February 2005

AbstractThe origin of the epicardium and the formation of the early blood vessels of the heart prior to the opening of the coronary arteries from the aorta have been studied in the 9–13.5 day post coitum (dpc) mouse embryo heart. The epicardium begins to appear by 9 dpc. The majority of the epicardial cells derive from the somatopleural investment of the septum transversum, from where they migrate, associated to form vesicles, to the dorsal aspect of the ventricles and atria. The epicardial cells then migrate over the lateral surfaces and the AV sulcus to the ventral aspect of the heart. In the subepicardial space around the sulcuses, the proliferating epithelial tissue is found, also in vesicular form, for a time. The ventrally migrating primordial epicardial tissue ensheaths lastly the truncus arteriosus, while the sinus venosus is coated with epicardium ab initio, where (and also in the SA sulcus) the epicardial cells derive in part from the cuboidal cells of the pleuroperitoneal canal and in part from the somatopleural cells. The early blood vessel formation follows in space and time the development of the epicardium. The first blood vessels appear by 10 dpc by the invagination of the endocardium into the early sinus muscle, and at the same time in the ventricular chamber by the encasing of the endocardium, as the trabeculae become consolidated into the myocardial walls. By this process sinusoids are formed, some of which penetrate through the myocardium and which, by rapid proliferation, form an interconnected subepicardial plexus. These capillaries proliferate ventrally in the wide subepicardial space, reaching the septating truncus, in which the aorta and pulmonary artery are developing. The definitive coronary artery openings appear by 13 dpc, allowing the high pressure blood from the aorta to flow into a preexisting vascular bed.
The wolff‐parkinson‐white syndrome and its anatomical substrates
Authors: Becker Anton E. , Anderson Robert H. 
Published: February 2005

AbstractThe anatomical substrates that underlie the clinical syndromes of preexcitation are still incompletely understood. Regarding the Wolff‐Parkinson‐White syndrome, there is increasing evidence that early ventricular activation is caused by accessory atrioventricular connections. These are muscular connections existing outside the specialized conduction tissue axis, which are almost always composed of working myocardial fibers. Left‐sided accessory atrioventricular connections have been identified with most frequency. They occur in the presence of a well‐developed fibrous annulus, thus contradicting the hypothesis that faulty development of the annulus is a necessary accompaniment. For right‐sided and septal connections, this developmental concept may still hold, since there is marked variability in the formation of the right‐sided annulus fibrosus. Even within these settings, however, the topography of accessory atrioventricular connections may vary considerably. Usually the accessory connection will pass on the epicardial aspect of the annulus fibrosus, particularly when leftsided. The connections are closely related to the fibrous annulus, but in other instances they may be in a superficial location. Multiple connections can occur in one heart. These anatomical features are of paramount significance for successful surgical ablation of accessory atrioventricular connections.
A proposed mechanism for the early development of the human tracheobronchial tree
Authors: Hutchins Grover M. , Haupt Helen M. , Moore G. William 
Published: February 2005

AbstractThe development of the lung in 25 human embryos and early fetuses up to 140 mm crown–rump length was studied by examination of serial histologic sections, morphometry, and selected reconstructions. The proportion of pulmonary tissue consisting of tracheobronchial tree increases during this period. Bronchial cross‐sectional diameter, length of the most distal bronchial branches, and thickness of the distal mesenchyme decline during development. The results are consistent with the concept that the dichotomous branching of the growing tracheobronchial tree occurs because of resistance to forward growth of the bronchial branch by compressed mesenchyme, pleura, or adjacent structures. Division and further growth of the bronchus takes place in areas of lower resistance. This process produces a “filling in” of space available for lung development and brings the epithelial and mesenchymal elements into their definitive relationships.
Regional differences in capillary density and myocyte size in the normal human heart
Authors: Stoker Mark E. , Gerdes A. Martin , May James F. 
Published: February 2005

AbstractSignificant regional morphometric differences are reported for the normal human left ventricle. Epimyocardial capillary density (2,439 capillaries/mm2) is 21% greater than endomyocardial capillary density (2,014 capillaries/mm2). The minimum intercapillary distance is, therefore, increased in the inner region. Endocardial myocytes (617 μm2) have a 53% greater cross‐sectional area than epicardial myocytes (403 μm2).
Femoral mechanics in the lesser bushbaby (Galago senegalensis): Structural adaptations to leaping in primates
Authors: Burr David B. , Piotrowski George , Martin R. Bruce , Cook P. Nong 
Published: February 2005

AbstractOne method used to examine the relationship between behavioral strategies and anatomical adaptation is to study the results of mechanical stress associated with a given behavior and compare this with skeletal adaptations to other behaviors. This comparative approach is appropriate for highlighting combinations of features that are specializations to specific types of behavior. The purpose of this paper is to compare femoral mechanics in Galago senegalensis with previously collected data for macaques and humans as a basis for discussing structural adaptations in the primate hindlimb to leaping. The stiffness and load carrying capabilities of the femoral diaphyses of 27 G. senegalensis were analyzed using the SCADS computer program. The data suggest that the galago femur is well adapted to sustain large sagittal plane compressive loads rather than large bending loads. The straightness of the femoral shaft and large midshaft area moments of inertia prevent buckling from these large compressive loads. Calculations indicate that the ratio of critical buckling load to body weight in galago is 31 times that in macaques and 55 times that in humans. The femur of this saltatory primate is morphologically adapted to resist buckling when subjected to large compressive loads, while those of macaques and humans are better adapted to resist bending moments caused by ground reaction forces acting on the extended limb. The differences between galago on the one hand and macaques and humans on the other suggest that relatively smaller moments about the hip and relatively larger moments about the knee accompany more quadrupedal and bipedal walking, while habitual leaping is associated with relatively larger moments about the hip. These data reinforce the apparent similarity of the mechanical effects of quadrupedal and bipedal locomotion on the femur and dissimilarity with femoral mechanics in habitually saltatory primates.
A quantitative histologic study of bone turnover in young adult beagles
Authors: Kimmel Donald B. , Jee W. S. S. 
Published: February 2005

AbstractThirty‐six regions of trabecular bone from two 18‐month‐old beagles and transilial biopsies of 25 female beagles aged 28–52 months were studied following in vivo double tetracycline labeling. Turnover rate varied from about 20% per year to 200% per year among the 36 regions. It was highest in the vertebral bodies and the proximal humerus, and lowest in the proximal ulna and foot‐bones. The mineral apposition rate varied from 0.35 to 1.02 μm/day, with a mean of about 0.7 μm/day, tending to be lower in areas of lower turnover. The specific surface varied from 10.9 to 23.8 mm/mm2 with a mean of 17.5 mm/mm2, tending to be higher in areas of high turnover. Specific surface varied only about twofold around the skeleton, while turnover varied by one order of magnitude. The average annual turnover rate for all trabecular bone in the young adult beagle is estimated at 140% per year. The accuracy of this estimate would be improved by knowing the exact mass of trabecular bone at each site.The annual turnover rate in the ilium of 25 female beagles was 134 ± 94% per year. The iliac trabecular bone turnover rate is two to three times faster in young adult female beagles than in young adult female humans. Using a human to beagle ratio of 1:2.5, the average annual turnover rate for all trabecular bone in the young adult human could be estimated at 40–55% per year. The beagle may be an appropriate model for certain experiments involving the adult bone remodeling system, because it may show a quicker response than humans to various experimental conditions and drugs, due to its faster turnover rate.
Histochennical properties of some jaw muscles of the lizard Tupinambis nigropunctatus (teiidae)
Authors: Throckmorton Gaylord S. , Saubert Carl W. 
Published: February 2005

AbstractIn many vertebrate limb and jaw muscles constituent fibers with differing contractile and metabolic properties are distributed so as to produce distinct intramuscular oxidative and glycolytic regions. The purpose of this investigation was to determine if similar compartmentalization exists in jaw muscles of the teiid lizard Tupinambis nigropunctatus. Nine jaw muscles from two adults and one juvenile were examined, and serial sections from each muscle were analyzed using histochemical techniques to indicate relative contractile, oxidative, and glycolytic capacities of the fibers and their patterns of distribution. Three distinct fiber types were observed. The histochemical profile of type 1 fibers most closely resembled that of tonic muscle fibers, while profiles of type 2 and type 3 fibers corresponded to those of fast‐twitch glycolytic (FG) and fast‐twitch oxidative (FO) fibers, respectively. Three muscles contained only type 2 (FG) fibers, and two muscles contained a noncompartmentalized mixture of all three fiber types. The remaining four muscles were distinctly compartmentalized, having a small, inneroxidative region containing primarily type 1 (tonic) and type 3 (FO) fibers and a larger, outer region consisting entirely of type 2 (FG) fibers. The possible relationships between fiber types, compartmentalization, and jaw function are discussed.
Association between mitochondria and rough endoplasmic reticulum in rat liver
Authors: Montisano Dominic F. , Cascarano Joseph , Pickett Cecil B. , James Thomas W. 
Published: February 2005

AbstractMitochondria were isolated from rat liver homogenate by both zonal and sedimentation equilibrium centrifugation. From electron microscopic examination of thin sections it was observed that 81% of the isolated mitochondria were in contact with rough endoplasmic reticulum (RER). Intact, non‐sectioned mitochondria subjected to negative staining procedures appeared to show points of connection between RER and the outer mitochondrial membrane. After treatment of mitochondria with digitonin to remove outer membranes, some of the resulting mitoplasts (intact inner membranes) remained closely associated with RER. Serial section analysis of intact rat liver indicated that RER saccules fit over mitochondria like caps providing broad areas of contact between the two organelles. The RER saccules were also observed communicating with more than one mitochondrion.
Fine structure of the testis in the toad (Bufo arenarum Hensel): A freeze‐fracture study
Authors: Cavicchia Juan C. , Moviglia Gustavo A. 
Published: February 2005

AbstractThe present work reports novel findings in the toad testis using freeze‐fracture techniques. Tight and gap junctions are observed in the nonfenestrated endothelial cells. Numerous gap junctions are present between interstitial cells. Sertoli‐Sertoli junctional specializations in the toad are similar to those described in mammals although they appear to be less elaborate. The appearance of nuclear pores, in the seminiferous epithelium, ranges from a uniformly and apparently random distribution in Sertoli cells to large aggregations of closely spaced pores separated by free areas in the nuclear envelope of spermatocytes. Inasmuch as these features have also been described in mammals, the fact that they are present in amphibia might indicate that they represent a widespread pattern.Concomitantly with increasing chromatin condensation, nuclear pores diminish in round spermatids and seem to disappear in the more mature germ cells. The en face freeze‐fracture views of annulate lamellae in the postnuclear cytoplasm and membranous features of the acrosome formation, flagellum, and undulating membrane of elongating spermatids are also described.
Ultrastructural immunocytochemical localization of carbonic anhydrase in normal and calcitonin‐treated chick osteoclasts
Authors: Anderson Richard E. , Schraer Harald , Gay Carol V. 
Published: February 2005

AbstractCarbonic anhydrase was localized in osteoclasts by light and electron microscopy using a preembedding peroxidase‐antiperoxidase staining method. Osteoclasts on the endosteal surface of the metatarsi of calcitonin‐treated and untreated (control) chicks were studied. A positive staining reaction was seen in the cytosol, in the Golgi apparatus, in and on vesicles, on the plasma membrane of the ruffled border, and on the bone surface beneath control osteoclasts. After calcitonin treatment, positive staining reactions were seen at the same sites except that staining was absent on the plasma membrane and endosteal bone surface. The morphology of osteoclasts from calcitonin‐treated chicks was indicative of cell inactivity. The carbonic anhydrase which was bound to the plasma membrane of the ruffled border is appropriately arrayed for hydrogen ion secretion and subsequent mineral dissolution. The presence of the enzyme within lysosomelike vesicles and on the endosteal surface beneath active cells suggests that it may be released into the resorbing zone along with the lysosomal hydrolases. The function of the extracellular enzyme is also unknown.
Description of the occlusion of the spinal cord lumen in early human embryos
Authors: Desmond Mary E. 
Published: February 2005

AbstractPrevious studies of both chick and human embryos have shown that the brain enlarges rapidly once the neural tube becomes a closed, fluid‐filled system. Prior to such enlargement, the medial walls of the spinal cord appear fused, occluding the lumen. This study describes occlusion of the lumen in terms of its incidence, location along the neuroaxis, time of occurrence, duration of occurrence, and morphology in human embryos. Eighty‐two human embryos (stages 9–15) from the Carnegie Collection were analyzed. Occlusion first occurs (and is most prevalent) in stage 11 embryos and is absent in embryos older than stage 13. In all cases examined, the neuroaxis demonstrated uninterrupted occlusion from the level of the third pair of somites to at least the ninth pair (i.e., approximately 60% of the neuroaxis was occluded). The appearance of the occluded neural tube in cross sections is similar to that of a soda straw that has been pinched between one's fingers.
The chorioallantoic placenta of the spotted hyena (Crocuta crocuta Erxleben): An electron microscopic study
Authors: Oduor‐Okelo Dominic , Neaves William B. 
Published: February 2005

AbstractThe histology and ultrastructure of the chorioallantoic placenta of the spotted hyena have been studied in three specimens obtained in the field and fixed promptly with glutaraldehyde. Observations revealed that the interhemal membrane at its minimal thickness is hemomonochorial, consisting of a continuous layer of syncytial trophoblast, a basal lamina, and fetal capillary endothelium. Cytotrophoblastic cells form a discontinuous layer beneath the syncytial trophoblast and are distinguished by the presence of numerous extracted lipid droplets in their cytoplasm. A network of extracellular spaces, incorrectly identified as cisternae of endoplasmic reticulum by earlier investigators, occurs beneath the maternal surface of the syncytial trophoblast. These spaces contain moderately dense, nonfibrillar material resembling the intrasyncytial lamina previously described only in the hemochorial placenta of certain bats. Hence, these spaces may contain remnants of maternal capillary basal lamina following displacement of the endothelium by extensions of syncytial trophoblast at an early stage of placental development.
Effects of the hypolipidemic drug Nafenopin on the zona fasciculata of the rat adrenal cortex: A correlated biochemical and stereological study
Authors: Mazzocchi Giuseppina , Robba Claudia , Rebuffat Piera , Belloni Anna S. , Nussdorfer Gastone G. 
Published: February 2005

AbstractThe effects of Nafenopin, a hypolipidemic drug, on the zona fasciculata of the rat adrenal cortex were investigated by biochemical, stereological, and cytochemical methods. Chronic Nafenopin treatment (5 days) significantly lowered serum cholesterol level, while it did not alter blood corticosterone concentration and 11β‐hydroxylase activity of adrenocortical cells. Stereology showed a significant increase in the average volume of zona fasciculata cells, which was almost exclusively due to smooth endoplasmic reticulum (SER) proliferation. The volume of lipid compartment was significantly reduced, whereas the volume of diaminobenzidine (DAB)‐positive bodies (peroxisomes) per cell displayed a marked increase. Cholesterol administration per os to the treated animals raised the serum cholesterol level and completely reversed the Nafenopin effects. One day of Nafenopin administration provoked a slight but significant lipid depletion in adrenocortical cells, while 3 days of continuous drug treatment induced an extreme lipid depletion and a moderate increase in the SER coupled with a significant decrease in the plasma concentration of corticosterone. Since microsomal fraction and catalase seem to be involved in the cholesterol metabolism and utilization, the hypothesis is advanced that the Nafenopin‐elicited SER and peroxisome proliferation is a compensatory response enabling adrenocortical cells to maintain an adequate level of hormonal output.