bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphogenesis of chordae tendineae. I: Scanning electron microscopy
Authors: Morse Dennis E. , Hamlett William C. , Noble Charles W. 
Published: February 2005

AbstractThe formation of the chordae tendineae of the left atrioventricular valve in the chick embryo is described using scanning electron microscopy. These supportive structures for the valve cusps develop between days 6 and 13 of incubation. Elevations which represent the primitive papillary muscles form on the ventricular wall. These elevations bifurcate into thin, weblike folds which are attached to the primitive valve cusps. The folds are the primordia of the chordae tendineae. Linear ridges develop on the web between the cusp and papillary muscle. These ridges alternate with depressions. The depressions become perforate to create the individual chorda from the linear ridges. Multiple perforations form initially but they typically consolidate to create one large aperture between two chordae. Some interchordal connections of tissue do persist throughout the period studied. During the period of perforation, prominent rounded cells are typical of the endocardium between the chordae. These cells are similar at the scanning electron microscope level to those present in the formation of the foramina secunda of the atrial septum. Primary, secondary, and tertiary chordae tendineae appear to develop in the same manner. First order chordae (those attached at the free margin of a cusp) are not found in the chick embryo. The majority of the chordae are second order, which insert into the ventricular surface of the cusp a short distance from the free edge. These chordae typically have a horizontal banding or grooving along their length. Third order chordae which extend from the papillary muscle to the ventricular wall are also present. It is suggested that chordal development is a programmed cellular and hemodynamic event.
Morphometry of articular cartilage: A stereological method using light microscopy
Authors: Paukkonen Kari , Selkäinaho Kalevi , Jurvelin Jukka , Helminen Heikki J. 
Published: February 2005

AbstractA stereological method is introduced for studying the light microscopic morphometry of articular cartilage. New parameters are presented for defining the three‐dimensional structure of the articular cartilage. These include volume density of the lacunae and nuclei, numerical density of cells in 3‐dimensional space, total number of cells, total volume of the lacunae in cartilage, volume and diameter of the lacuna and nucleus, the nucleus/lacuna volume ratio, and the mean volume of the matrix per cell. Using the lateral tibial condyle of the knee joint of eight rabbits, we investigated tissue preparation, sampling, morphometry, and the conditions necessary for validity and precision of the estimators. The method proved easy to use, and the estimators were precise.
A simplified method for hand‐made oblique graphical reconstructions
Authors: Claeys Hendrik , Aerts Peter 
Published: February 2005

AbstractThe present paper deals with a convenient, manual method for making oblique graphical reconstructions from serial sections. The method is based on a projection on the plane of drawing of a three‐dimensional coordinate system, which is submitted to two successive and predetermined spatial rotations. Restriction to two rotations simplifies the mathematical approach to a coordinate transformation from a three‐dimensional into a two‐dimensional system. The resulting formulae, which are quite easily applied, lead to a quick visualization procedure.
Ultrastructural localization of carbonic anhydrase in lysosomes
Authors: Rikihisa Yasuko 
Published: February 2005

AbstractUltrastructural localization of carbonic anhydrase was determined by applying Hansson's histochemical method to glutaraldehyde‐fixed frozen sections of guinea pig peritoneal polymorphonuclear leukocytes (PMNs) and lysosomes isolated from rat liver tissue after the animal had been injected with Triton WR‐1339. A positive histochemical reaction for carbonic anhydrase in PMNs was found in the matrix of lysosomes. After PMNs phagocytized polystyrene latex particles or emulsified paraffin oil droplets, a positive reactivity for carbonic anhydrase was found in the space between the lysosomal membrane and the particle. Liver lysosomes also revealed positive carbonic anhydrase histochemical reactivity. To confirm the histochemical reaction, indirect immunoferritin labeling was conducted with rabbit antibody to human red blood cell carbonic anhydrase C on glutaraldehyde‐fixed, freezethawed human PMNs. Immunolabeling was observed in lysosomes. These results suggest that carbonic anhydrase is a constituent of lysosomes of PMNs and liver cells.
Development of mouse embryos in hanging drop culture
Authors: Potter Sandra W. , Morris John E. 
Published: February 2005

AbstractMouse blastocysts were cultured in hanging drops for up to 6 days in order to study development under conditions that avoid the distortion of embryos typically seen when they are allowed to attach to a glass or plastic surface. The survival rate of embryos in hanging drops was equal to that of embryos attached to culture dishes and superior to that of embryos suspended in gyrating flasks. Development of the embryonic portion was similar to that in vivo and on culture dishes but slower than in vivo; the egg cylinder stage was reached after 8–10 equivalent gestation days (4 to 6 days in culture), while that stage is reached at 5.5 to 6 days in vivo. The trophectoderm, however, developed in a unique manner. The cells migrated away from the inner cell mass (ICM), similar to embryos on a culture dish, but without a surface on which to spread they clustered distal to the ICM. In vivo, trophectoderm remained covering the ICM. By 5 days in hanging drop culture the embryos had developed a segmented appearance with trophoblast giant cells at the abembryonic pole, extraembryonic cells not covered by vacuolated endoderm in the central region, and embryonic endoderm surrounding a developing proamniotic cavity in embryonic ectoderm at the embryonic pole. These observations suggest that the trophectoderm is able to follow a developmental program independent of that in the embryonic portion and that its behavior is dominated by the different adhesive properties of the trophoblastic and embryonic cells.
Spinal tanycytes in the adult rat : A correlative Golgi gold‐toning study
Authors: Rafols José A. , Goshgarian Harry G. 
Published: February 2005

AbstractIn Golgi impregnated transverse sections through the cervical spinal cord of the 7–12‐week‐old adult rat, numerous tanycytes were observed radiating from the ependyma into the gray matter that surrounds the central canal. The tail processes of these tanycytes terminated as foot processes in association with blood vessels. Spinal tanycytes were classified into ependymal (E) and subependymal (S) types on the basis of the shape and position of the soma. The soma of the E tanycyte was shaped as a column and was entirely located within the ependyma. In contrast, the soma of the S tanycyte was flask shaped, with the widest portion of the flask located subependymally and the elongated portion extending through the ependyma ultimately reaching the luminal surface. Selected Golgi impregnated sections were gold toned and deimpregnated for direct correlative analysis at the ultrastructural level. Gold‐toned tanycytes contained the fine clusters of gold particles underlying the plasma membrane of the cell body and coarse clusters of gold particles throughout the tail and foot processes. The apical surface of tanycytes was characterized by numerous microvilli and large cytoplasmic protrusions that evaginated from the apical surface into the lumen of the central canal. At the luminal surface, adjacent tanycytes were joined laterally by junctional complexes with punctate tight junctions and zonulae adhaerentes associated with fibrils and microtubules. In contrast, gap junctions, hemidesmosomes, and puncta adhaerentia were found between adjacent tail processes of tanycytes. The foot processes interdigitated with one another and abutted the basal lamina around the perivascular space of blood vessels. The basal lamina was continuous around the lateral walls of foot processes and filled the spaces between membranous infoldings of the lateral walls. These basal membrane labyrinths were continuous with the basal lamina of the blood vessel and may provide an extensive surface relation between the perivascular space and the neighboring extracellular compartment. The findings of the present study support the contention that tanycytes may modify the composition of substances moving between the perivascular and extracellular spaces.
Statistical significance tests for autoradiographic data
Authors: Skipper Betty J. , McGuffee Linda J. 
Published: February 2005

AbstractThe purpose of this paper is to develop statistical methods that take radiation spread into account in analyzing data from different autoradiographic experiments. The method uses the probability circle analysis of Salpeter and McHenry (1973) to obtain the probable source of each radioactive emission and the circle and point counting method of Williams (1969) to estimate the relative area occupied by each cellular site. Two levels of analysis are presented. The first level of analysis is concerned with estimating relative activities and standard errors for cellular items that are larger than the probability circle. The second level of analysis involves estimating relative activities and standard errors for cellular sites that are smaller than the probability circle and are therefore observed in circles containing another item such as cytoplasmic matrix. Two different tests of hypotheses are discussed. The first null hypothesis is that the radioactivity is randomly distributed among the cellular sites. The second null hypothesis is that there is no difference between two different treatments in the relative activities for a given site.
Odontoblast turnover in the impeded and unimpeded rat incisor derived from computerized histomorphometry
Authors: Weinreb M. , Steigman S. , Zajicek G. , Michaeli Y. 
Published: February 2005

AbstractA computerized histomorphometric method was devised to estimate the kinetics of odontoblast turnover and dentinogenesis in rat incisors. The method was applied to two groups of rats: one group with lower incisors in impeded eruption and another group with the left lower incisor in the unimpeded state. The teeth were divided into six equal segments, from which consecutive ground sections were obtained. The distance of each ground section from the posterior border of the alveolar bone was calculated. Each section was magnified, traced, and the tracings fed into a computer by a sonic digitizer. The perimeters and areas of dentine and pulp in each ground section were calculated by the computer. The mean odontoblast density along the predentine was evaluated from histological sections taken both from the same tooth segments and from teeth sectioned midsagittally. These served for the estimation of the predentine area occupied by the average odontoblast. In the impeded group, this area was 11% larger than in the unimpeded one. Outer dimensions of teeth, namely the circumference of the dentine, the labiolingual width, and the mesiolateral width remained constant and equal for both groups.Daily rates of dentine apposition were computed and were found to vary according to the age of the odontoblasts. Odontoblasts of impeded teeth started to secrete matrix at a rate of 17 μm/day, which increased slightly to 19 μm/day and later declined to 7 μm/day on the 38th day. Dentine production of unimpeded odontoblasts, on the other hand, started at a rate of 16 μm/day and gradually increased to 34 μm/day on the 17th day. The daily rate of odontoblast cell‐production was 2.29 times greater in the unimpeded teeth (112.9 × 103 cells/day instead of 49.4 × 103 cells/day). The absolute mean daily rate of odontoblast cell loss increased in unimpeded teeth from 33.1 × 103 cells/day to 42.9 × 103 cells/day. On the other hand, the relative daily rate of cell loss decreased from 73.6 cells/day/1μm eruption to 47.7 cells/day/1μm eruption.
Activation of actin‐containing microfilaments by vasopressin in the amphibian urinary bladder epithelium: A fluorescent study using NBD‐phallacidin
Authors: Davis Walter L. , Gwendolyn Jones Ruth , Richemont Phillip C. , Goodman David B. P. 
Published: February 2005

AbstractThe effect of an antidiuretic hormone (ADH, vasopressin) on the microfilament system of the toad urinary bladder lumenal epithelium was investigated using NBD‐phallacidin (NBD‐ph). The latter material is a specific fluorescent label for F actin. In the presence of an osmotic gradient, both ADH and cyclic adenosine monophosphate (cAMP) appear to induce the polymerization of monomeric actin into F actin‐containing microfilaments. The latter may then be involved in the morphological changes, including the formation of lateral intercellular lakes, associated with the typical hydroosmotic response.
Fluid‐phase and adsorptive endocytosis in ciliated epithelial cells of the rat ductuli efferentes
Authors: Hermo L. , Clermont Y. , Morales C. 
Published: February 2005

AbstractCiliated cells of the ductuli efferentes show at their apex a discrete endocytic apparatus composed of small vesicles connected to or subjacent to the apical plasma membrane, small apical membranous tubules, and pale multivesicular bodies. Deeper in the cytoplasm, there are acid phosphatase‐positive denser, multivesicular bodies and secondary lysosomes showing an electron‐dense cortex and a crystalline, paler stained core. Cationic ferritin and concanavalin A‐ferritin used to demonstrate adsorptive endocytosis, when injected into the rete testis, rapidly reached the lumen of the ductuli efferentes. At 1 min after injection, these tracers were seen bound to the apical plasma membrane of ciliated cells and within small endocytic vesicles and by 5 min in narrow apical tubules. At 15 and 30 min after injection, the tracers appeared in pale multivesicular bodies while at 1 hr they were found within dense multivesicular bodies. At 2 hr and longer time intervals these tracers accumulated within secondary lysosomes. Native ferritin, concanavalin A‐ferritin in the presence of α‐methyl‐D‐mannoside, and horseradish peroxidase or albumin‐colloidal gold complexes were used to analyze fluid‐phase endocytosis. At various intervals following their injection into the rete testis, these tracers presented a distribution identical in all respects to that described for cationic ferritin and concanavalin A‐ferritin. In the present work, none of the above tracers were transported to the abluminal aspect of the ciliated cells. These cells, like the nonciliated epithelial cells of the ductuli efferentes are thus involved in adsorptive as well as in fluid‐phase endocytosis.
Chronic changes in male rats' hormone‐sensitive systems after suprathreshold pulses of testosterone
Authors: Taylor George T. , Weiss Jürgen , Haller John 
Published: February 2005

AbstractAdult male rats were castrated and maintained on daily SC injections of a threshold amount (200 μg) of testosterone propionate (TP). To mimic naturally occurring pulses of suprathreshold testicular hormones in intact males, animals in the experimental groups also received either one (single TP) or five (multiple TP) injections of 800 μg TP over 12 days. The rats were examined on the following day (acute) or 15 days later (chronic) for changes in hormone‐sensitive behavior, physiology, and morphology. The hypothesis tested was that the hormonal pulses function to provoke chronic changes in substrates underlying the reproductive system. The results were that multiple doses of suprathreshold TP provoked acute modifications in aggressive behavior, sex accessory glands, and glans penis integrity. Chronic changes were observed in sex accessory gland functioning and penile morphology, particularly in the size of penile papillae. A single exposure to suprathreshold TP was considerably less effective, though there was some evidence of acute changes in sex accessory glands and chronic changes in penile papillae. There was substantial variation in the responses of individual animals, particularly the chronic responses. The data were interpreted as supporting the hypothesis.
Quantitative and comparative stress analysis in human femur under two different static situations by three‐dimensional photoelasticity
Authors: Bianchi Rossella , Clerici Paolo , Miani Alberto 
Published: February 2005

AbstractUsing the three‐dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight‐bearing situation on two legs.The results obtained show that in this loading situation the maximum stress values (both for tension and compression) are in the area just below the subtrochanteric zone; while going up along the borders of the diaphysis, the tension trends do not vary appreciably.Moreover, the state of the stresses is not constant but varies slightly along the thickness of the bone. The neutral axis is considerably displaced towards the tensile area.A comparison between the stress tension trends in two different static loading situations (one‐leg and two‐leg support) was carried out.It was found that the maximum tensile stress value in the one‐leg position was about 24 times greater than that in the two‐leg position and the maximum compression stress value was about 14 times greater than in the two‐leg situation.
A quantitative microprobe analysis of elements in cortical and nuclear cells of the calf lens
Authors: Neuringer Julia R. , Clark John I. , Benedek George B. 
Published: February 2005

AbstractThe outer cortical cells in the calf lens remain transparent under conditions that produce opacity in central nuclear cells. The nuclear cells opacify by a mechanism of cellular restructuring that is associated with a cytoplasmic phase separation while cortical cells do not opacify by this mechanism. In this study the differences in elemental composition of nuclear and cortical cells were analyzed using X‐ray emission spectroscopy (XES) of tissue that was prepared for scanning electron microscopy. It was necessary to develop special methods of fixation and dehydration to prevent significant distortion of lens tissue and minimize solubilization and redistribution of elements during the histological processing of the tissue. We calibrated the microprobe for the quantitative analysis using gelatin standards which contained known concentrations of sulfur, potassium, phosphorus, chlorine, and cesium. The standard curves were used to determine proportionality constants, which related the intensity of X‐ray emission to the molar concentration of each element, and to determine the minimum detectable levels of each element. An important finding is that the intensity of the X‐ray emission is dependent on sample density only at low protein concentration. At the high protein concentrations that exist in lens, the intensity is not affected by sample density. The results are that (1) normal concentrations of sulfur, phosphorus, and potassium can be localized using this procedure; (2) concentrations of sodium, magnesium, chlorine, and calcium are just below the sensitivity of the present method in the normal lens; 3) lenses that are placed in solutions of monovalent ions have increased concentrations of the ions in both the nucleus and cortex, but only the nuclear cells opacify; and 4) the greatest detectable difference between the cells in the lens nucleus, which opacify, and cells in the lens cortex, which do not opacify, is in the phosphorus content. Cortical cells contain five to six times as much phosphorus as nuclear cells.
Mucous cells and cell migration in the mouse duodenal epithelium
Authors: Bjerknes Matthew , Cheng Hazel 
Published: February 2005

AbstractThe distribution of mucous cells in the mouse duodenum was used to determine whether or not intestinal epithelial cells move as a sheet during their migration from crypts to villi. The experiments took advantage of the probable symmetry of mucous‐cell divisions (symmetry in the sense that each mucous‐cell division produces two mucous cells). Since approximately 50% of newly formed mucous cells are derived from mucous‐cell divisions, at least 50% of newly formed mucous cells in the crypt should be found in mucous‐cell pairs. It follows that if the epithelium moves as a firmly interconnected sheet, at least 50% of mucous cells found in the villus should also be in pairs. On the other hand, if a significant amount of cell mixing occurs during migration, the pairing tendency of mucous cells would be lost. Mucous‐cell pairing was determined by two independent methods: (1) direct observation of mucous‐cell pairs and (2) the application of Poisson statistics to the mucous‐cell distribution to determine a “pairing tendency.” We found that in the crypt at least 75–80% of newly formed mucous cells occur in pairs, while in all regions of the villus (base, middle, and top) mucous cells are distributed randomly. These results strongly indicate the existence of a significant amount of cell mixing in the epithelium at some point between the site of mucous‐cell formation in the crypts and the villus base. Since the mucous‐cell population was randomly distributed in all regions of the villus we were unable to determine whether or not additional cell mixing occurs in the villus epithelium.
Substance P immunoreactivity in the major pelvic ganglion of the rat
Authors: Dail William G. , Dziurzynski Rene 
Published: February 2005

AbstractSubstance P immunoreactivity in the major pelvic ganglion (MPG) of the rat was studied to define a possible role for this neuropeptide in functions of the pelvic portion of the autonomic nervous system. Substance P immunoreactivity was found in three locations in the ganglion: (1) as a plexus of varicose fibers, (2) in small intensely fluorescent (SIF) cells, and (3) after colchicine pretreatment, in some principal neurons. The perineuronal plexus of fibers appeared as small varicosities closely related to the somae of principal neurons. Approximately 10–20% of principal neurons were enclosed by a substance P‐positive plexus. SIF cells were intensely stained for substance P. The general relationships of SIF cells in this ganglion were confirmed by their staining for substance P: their occurrence singly or in large clusters, their short tapering processes often related to principal neurons, and the occasional presence of a beaded process. Colchicine treatment resulted in the appearance of rare principal neurons that stained for substance P. The pelvic nerve was surgically interrupted to determine whether the perineuronal plexus of varicose fibers had an intrinsic origin or arose from cell bodies outside the ganglion. The perineuronal plexus was virtually absent following this procedure. The results of this study indicate that principal neurons in the major pelvic ganglion may be subject to the influence of substance P derived from two sources: (1) intrinsic substance P‐containing SIF cells and (2) neurons probably residing in dorsal root ganglia. The nature of principal neurons that acquire staining for substance P after colchicine is unclear.