bluuebunny/crossref_metadata_2025_split huggingface dataset:
The chorda center in Hensen's node of the chick embryo
Authors: Rosenquist Glenn C. 
Published: February 2005

AbstractTo learn the origin and early migration of notochordal cells in the chick embryo, tritiated thymidine‐labeled grafts were implanted into homologous positions in Hensen's node of recipient embryos at homologous stages of development. The host embryos were reincubated to Hamburger‐Hamilton stages 5–9, fixed, embedded in paraffin, and serially sectioned. Sections were coated with photographic emulsion and exposed for 7–30 days. Labeled cells were found in the notochord or chordamesoderm in 31 of the 35 embryos.Transplants to the dorsal portion of the node always formed notochord. Transplants to the ventral node formed notochord only when implanted during or after the definitive streak stage (H‐H stage 4+), indicating that the chorda center is located in the dorsal layer. Moreover, the results suggest that the node depletes itself in producing the notochord: labeled cells migrated into notochord or chordamesoderm anterior to the primitive pit, rather than remaining in the node or primitive pit. Because transplants to the anterolateral portion of the node contributed only to trunk notochord and several transplants to the posteromedial portion contributed only to head notochord, Hensen's node may be equivalent to the median lip of a blastopore, over which prenotochordal material in the dorsal (epiblast) layer passes during gastrulation.
A simple technique for the visualization of whole mount cytoskeletons with transmission electron microscopy
Authors: Marek Louis F. , Kelley Robert O. 
Published: February 2005

AbstractExamination of whole mount cells in the transmission electron microscope has been useful in studies of cellular architecture. The common technique is to grow cells directly on formvar‐coated, gold grids for direct observation through a cell. We report a technique for obtaining whole mount preparations which requires neither fragile formvar films nor expensive, gold grids. Cells are grown on palladium‐coated coverslips and processed for electron microscopy. The cells and the palladium substrate are separated from the coverslip. The cell‐palladium complex is then picked up on copper grids as in thin section processing. We compare images of the cytoskeleton using our technique with images using previously described techniques and present preliminary observations of contracting cell models. Such contractions would tear formvar films if attempted on cells grown in the conventional manner for whole mount examination. Our technique allows cells to contract without tearing the underlying substrate.
Cell production in mouse intestinal epithelium measured by stathmokinetic flow cytometry and coulter particle counting
Authors: Cheng Hazel , Bjerknes Matthew 
Published: February 2005

AbstractThe rate of cell production in the crypt population of the intestinal epithelium has been determined previously. However, the complex geometry of the tissue makes determination of the rate of cell production in the epithelium as a whole, by traditional methods, extremely difficult if not impossible. In this report, stathmokinetic flow cytometry was used for the direct determination of the rate of cell production in the mouse intestinal epithelium. Mice were given an intraperitoneal injection of colcemid (2.5 mg/ kg) and killed 25, 45, 65 and 90 min after injection. The percentage of cells with 4N DNA (G2 and M phase cells) in the epithelium at each time interval was determined with flow cytometry. The results were fitted by linear regression and the rate of cell production derived from the slope of the regression line. Thus, the rate of cell production was found to be 1.86% ± 0.44 (x ± SE) per hour in the jejunal epithelium and 1.66% ± 0.48 per hour in the colonic epithelium. The turnover time of the epithelium as a whole was determined from the inverse of the rate of cell production, and was found to be 53.8 h ± 12.6 in jejunum and 60.2 h ± 17.3 in colon. Coulter particle counting was used to measure the number of cells in the intestinal epithelium. The number of epithelial cells was found to be 1.90 × 107 ± 3.11 × 105 cells per cm2 in the jejunum and 8.98 × 106 ± 8.05 × 105 cells per cm2 in the colon. A number of other kinetic parameters, which were not available, were derived from the values determined in this study. For example, it was estimated that 3.53 × 105 ± 8.33 × 104 cells were produced per cm2 per hour in the jejunal epithelium, and 1.49 × 105 ± 4.45 × 104 cells per cm2 per hour in the colonic epithelium. The rate of cell production at the level of the crypt was found to be 25.1 ± 6.44 cells per crypt per hour in the jejunum, while in the colon 16.4 ± 5.20 cells were produced per crypt per hour. In the jejunum, it was concluded that on the average, about 241.0 ± 65.8 cells were lost each hour from a villus. The kinetic profle of the crypt was also derived. There were on the average about 609.0 ± 50.5 cells per crypt in the jejunum and 985.0 ± 77.98 cells per crypt‐surface epithelium unit in the colon. Of these, about 310 cells constitute the cycling population in a jejunal crypt while about 305 cells constitute the cycling population in a colonic crypt‐surface epithelium unit. The cycling population in a jejunal crypt was distributed approximately as follows: 91 cells in the G1 phase, 171 cells in the S phase, 48 cells in the G2 + M phases. The cycling population in a colonic crypt‐surface epithelium unit was distributed approximately as follows: 140 cells in the G1 phase, 124 cells in the S phase, and 41 cells in the G2 + M phases.
Increase in zymogen granule volume accounts for increase in volume density during prenatal development of pancreas
Authors: Ermak Thomas H. , Rothman S. S. 
Published: February 2005

AbstractThe sudden increase in volume density of zymogen granules in acinar cells of the fetal rat pancreas was examined with particular attention to the respective roles of granule size and number in this event. Volume density increased some twelvefold, from about 3% of cytoplasmic volume at 17 days to about 45% at 20 days, following a sigmoidal pattern in which the greatest rate of increase occurred during day 18. This increase in volume density was primarily the result of an increase in granule volume. Zymogen granule diameter increased from 0.55 μm at 17 days to 1.20 μm at 20 days, an order of magnitude increase in average granule volume. The total number of granules in the tissue increased in proportion to the increase in organ weight (cell number and size), but changes in the number of granules per unit cytoplasmic volume were minor (+ 40%) in comparison to the increase in volume density. The distribution of granule diameter was roughly normal and unimodal at each time interval, and the increase in average diameter over time was marked by an increase in the upper limit of the size distribution and an increased percentage of large granules. The size of condensing vacuoles also increased during this period, and their distributions were roughly coextensive with those seen for zymogen granules at the same time. The potential origins of changes in granule size are discussed, as well as the important effect that size has on the number of granules observed in “two‐dimensional” tissue sections viewed in the electron microscope. If size is not considered in our estimates, then we underestimate the numerical density in cells with small granules compared to those with large granules. The results indicate the central role of granule size, as opposed to number, in determining granule volume density in the embryonic pancreas.
Identification of human second, third, and fourth metatarsal bones
Authors: Batmanabane Mounissamy , Malathi Santhanagopalan 
Published: February 2005

AbstractThe lateral side of the base of the second (SMT), third (TMT), and fourth (FMT) metatarsal bones displays constant and distinct grooves. The groove on SMT starts just above the middle of the lateral surface of the base and runs toward the shaft forming an angle of 85–111o with the base. TMT has a groove starting at about the middle of the lateral surface forming an angle of 57–72o with the base, while the groove on FMT runs upward more acutely, starting from the lower end of the surface, forming an angle of 37–54o with the base. The presence of these grooves and the usefulness of their characteristics in distinguishing between these metatarsals, especially in forensic medicine, is discussed.
A quantitative ultrastructural analysis of satellite cells in denervated fast and slow muscles of the mouse
Authors: Snow Mikel H. 
Published: February 2005

AbstractMononucleated cells located between the external lamina and sarcolemma of denervated muscle fibers within the extensor digitorum longus (EDL) and soleus muscles of adult mice were quantified and examined ultrastructurally from 3 to 65 days after ligating and removing a section of the sciatic nerve. During the first 2 weeks postdenervation, mononucleated cells in denervated muscles were morphologically indistinguishable from satellite cells observed in control muscles. With time, however, many of these satellite‐like cells appeared more active as evidenced by a decrease in their nucleocytoplasmic ratio and an increase in their mean percentage of euchromatin material. The number of satellite cells (expressed as a ratio of satellite cell nuclei to satellite cell nuclei plus myonuclei) did not increase significantly until 30 days postdenervation, at which time the mean percentage for the soleus muscle had risen from a control value of 4.1–8.5%, and for the EDL from 1.2–4.1%. Smalldiameter, presumably regenerating, myofibers were occasionally observed but only after 30 days denervation. The ultrastructural evidence plus comparisons of euchromatin distributions between myonuclei and satellite cell nuclei support the concept that an increase in the number of satellite‐like cells during denervation is more likely due to satellite cell proliferation than to the formation of mononucleated fragments utilizing preexisting myonuclei.
Cytochemical study on the distribution of adenylate cyclase in guinea pig testis
Authors: Pascolini Rita , Vagnetti Daniela , Spreca Antonio , Marinelli Marinella , Lorvik Sergio 
Published: February 2005

AbstractThe distribution of adenylate cyclase in testis, by means of a specific substrate adenylyl‐imidodiphosphate (AMP‐PNP), has been determined. Membrane‐associated reaction products, indicative of adenylate cyclase activity, are localized by a complete cytochemical medium (containing 10 mM NaF) at the level of the basal compartment of the seminiferous epithelium, on the basal surface of Sertoli cells, and on adjacent plasma membranes of Sertoli cells and spermatogonial cells. At the level of the adluminal compartment, reaction products were found on adjacent plasma membranes of Sertoli cells and early or elongated spermatids. Adenylate cyclase reaction products are detectable by a basal incubation medium (without 10 mM NaF) only in the adluminal compartment on the spermatid plasma membranes.
Fluorescence microscopic morphometry of functioning blood vessels and adrenergic nerves in myocardium
Authors: Muntz Kathryn H. , Hagler Herbert K. , Boulas H. Jay , Buja L. Maximilian 
Published: February 2005

AbstractThe purpose of this study was to quantify the percent volume of actively functioning blood vessels in five dogs subjected to ligation of the left anterior descending artery and to localize catecholamine‐containing nerve terminals in the same tissue blocks. Radioactive microspheres were injected to determine the extent of flow reduction in the ischemic zone. After 1 or 3 hr of occlusion, thioflavin‐S (0.125 ml/Kg of a 4% solution) was injected intravenously 15 sec prior to removal of the heart. Tissue samples were reacted with paraformaldehyde to visualize catecholamine‐containing nerve terminals prior to embedding in paraffin. The percent volume of blood vessels labeled with thioflavin‐S was quantitated in tissue sections using a point‐counting technique in which a small dot from a video screen was projected through an image‐projecting tube and moved by computer control over the image of the fluorescent tissue. In the nonischemic zone, the mean blood flow determined by the microsphere technique was 1.29 ml/min/g ± 0.48 (SD), and the mean volume percent of thioflavin‐labeled vessels was 12.67 ± 3.30. In the ischemic and border zone areas, there was wide range of flow reduction, and there was a significant correlation between the blood flow measured with microspheres and the percent volume of thioflavin‐labeled blood vessels (R = 0.80, P < 0.001). In the nonischemic zone, both blood vessels and catecholamine‐containing nerve terminals were visible; however, in the ischemic zone, few labeled vessels were seen, although nerve terminals were often present. A method has been presented here in which blood flow can be predicted microscopically in a small sample of tissue using a unique method of point counting of fluorescent tissue sections.
Evidence for the persistence of axons at the apex of the cat's lower canine tooth after section of the inferior alveolar nerve
Authors: Holland G. R. , Robinson P. P. 
Published: February 2005

AbstractThe aim of this investigation was to establish the degree of denervation produced by inferior alveolar nerve section and to provide histological evidence for the presence of pulpal nerve fibres supplying the teeth which do not travel with the inferior alveolar nerve. Four adult cats were used. Each stage of the experiment was carried out under general anesthesia. The left inferior alveolar nerve was exposed and sectioned near the mandibular foramen. After 56 hours and 7 days, respectively, the jaw opening reflex to electrical stimulation of each lower canine was tested. Recordings were made from the left canine during electrical stimulation of the ipsilateral inferior alveolar nerve central and peripheral to the site of section as well as from the ipsilateral and contralateral inferior alveolar nerve during electrical stimulation of the left canine. Recordings were also made from the lingual nerve. After the recordings were completed two animals were perfused 56 hours after inferior alveolar nerve section, two more 7 days after section. Ultrathin sections of the apices of the lower canine teeth were examined in the electron microscope and each nerve fibre photographed. Each axon was examined to determine whether it was degenerating or normal.A jaw‐opening reflex could not be elicited by stimulation of the left canine either 2 or 7 days after nerve section, whereas a normal response was evoked by stimulation of the right, control canine. At 2 days small responses could be recorded from the left canine teeth during stimulation of the left inferior alveolar nerve peripheral to the point of section. In one 2‐day animal, responses could be recorded in the lingual nerve during stimulation. No pulpal fibres could be recorded in the inferior alveolar nerve central to the point of section nor from the contralateral inferior alveolar nerve. No pulpal fibres supplying the left canine could be recorded in any of the nerves examined at 7 days.Extensive degeneration was seen histologically even at 2 days. The canine pulp on the operated side contained only 31%, in one animal, and 26% in the other, of the number of axons of normal appearance that were present on the control side. At 7 days the number of remaining normal axons on the operated side were 5% and 13% of the numbers on the control side. All the axons of normal appearance were nonmyelinated.It is possible that the remaining axons represent fibres carried by the lingual nerve or some other alternative pathway that could not be detected electro‐physiologically. Alternatively they may be a collateral innervation from adjacent tissues.
Immunocytochemical localization of four hormones in the pancreas of the garter snake, Thamnophis sirtalis
Authors: Rhoten William B. 
Published: February 2005

AbstractInsulin, glucagon, somatostain, and pancreatic polypeptide (PP) were localized in the pancreas of the common garter snake, Thamnophis sirtalis, by light and transmission electeron microscopic (TEM) immunocytochemistry. Colloidal gold‐protein A was used for TEM localization and the peroxidase containing A cells and the insulin‐positive B cells were the most numerous cell types. The somatostatin‐containing D cells made up about 15% of the endocrine cells. PP‐positive F cells were a minor cell type. The only topographic arrangement of the cells within the endocrine‐rich areas that was apparent was the peripheral localization of the D and F cells. Cells of a specific cell type were sometimes grouped together. At the elctron microscopic (EM) level, the gold particles (indicating the pesence of hormone) were localized nearly exclusively over the secretory grnules of the ractive cells. The α‐granules were the largest found and were predominantly electron dense with a moderately electron‐dense periphery. PP‐containing granules were the smallest. The somatostatin‐reactive δ‐granules were round and moderately electron opaque. The β‐granules were heterogeneous in appearance. The morphognomy of the secretory granules of the major endocrine cell types is qualitatively similar to that of mammals. Wheter or not the quantitative and/or associative differences contribute to the marked metabolic differences between reptiles and mammals, remains to be determined.
Meckel's diverticulum. II. A novel lymphoepithelial organ in the chicken
Authors: Oláh I. , Glick B. , Taylor R. L. 
Published: February 2005

AbstractWe have studied the lymphoid development and structure of Meckel's diverticulum (MD). The lymphoid accumulation began about 2 weeks of age. Between 2 and 5 weeks of age the longitudinal folds were filled with lymphoid tissue. The intensive germinal center formation occurred between 5 and 7 weeks of age. Germinal center formation was associated with the presence of secretory cells. The absence of the secretory cells in the germinal centers was followed by germinal center inactivity which was indicated by the lack of lymphoblasts and the high number of tingible body macrophages.The lymphoid tissue of MD seemed to be fully developed by 10 weeks of age and remained lymphoid at least until 21 months of age. Meckel's diverticulum produced large numbers of plasma cells which were comparable to those of the gland of Harder. We may regard MD as the third pouch of the intestine and suggest that it may be a novel lymphoepithelial organ in the chicken.
A quantitative study of satellite cells in regenerated soleus and extensor digitorum longus muscles
Authors: Schultz Edward 
Published: February 2005

AbstractSatellite cells quantitated in the rat soleus and extensor digitorum longus (EDL) muscles following a complete regeneration returned to “normal” percentages of myofiber nuclei in both muscles 3 months after injury. Following cross‐transplantation, the percentage of satellite cell nuclei in the EDL regenerated in the soleus bed was indistinguishable from the percentage in the soleus. Likewise, the soleus muscle regenerated in the EDL bed had a satellite cell percentage characteristic of the EDL. These results suggest that (1) the proportion of satellite cells is reestablished in a regenerated muscle and (2) the innervating nerve determines the proportion of satellite cell nuclei in a muscle.
The development of specific antibody‐containing cells in the spleen of rabbits during the secondary immune response against free or liposome‐associated albumin antigen
Authors: van Rooijen N. , van Nieuwmegen R. , Kors N. , Eikelenboom P. 
Published: February 2005

AbstractIn order to study the distribution pattern of specific antibody containing cells in the spleen of rabbits during the secondary immune response, rabbits were given two intravenous injections of either free or liposome associated human serum albumin (HSA) within an interval of 2 months. Demonstration of specific antibody‐containing cells was performed by incubation of sections of spleen with HSA‐horseradish peroxidase (HRP) conjugates, followed by peroxidase cytochemistry.Specific anti‐HSA antibody‐containing cells were detected already within 2 days after booster and peak numbers were found 4 days after booster. The bulk of these cells localized in the coaxial lymphocyte sheaths surrounding the terminal arterioles in the spleen. Specific antibody‐containing cells produced immunoglobulin G (IgG) antibodies. From the results, it is also concluded that, after a priming injection with liposome‐associated HSA, liposomes do not further enhance the secondary immune response, when they are also used for the booster injection.
Localization of a synthetic progestin in the reproductive organs of the female baboon
Authors: Weaker Frank J. , Sheridan Peter J. 
Published: February 2005

AbstractThe uptake and retention of a radiolabeled synthetic progestin, ORG 2058, was studied in the female reproductive system of the baboon. Four estrogen‐primed baboons were injected intravenously with 2.5 μ/kg body weight of 3H‐ORG 2058. One animal, which served as a control, received an additional injection of 2.5 mg/kg body weight of unlabeled progesterone. One hour after the injections, the animals were killed and the uterus, cervix, oviduct, vagina, and labia were removed and processed for autoradiography. The cells in the germinative layers of the stratified squamous epithelium of the cervix, vagina, and labia demonstrated nuclear localization of the label. The columnar epithelium, both surface and glandular, of the uterus and cervix sequestered the synthetic steroid; however, the nuclei of the epithelium lining the oviduct were unlabeled. The nuclei of the fibroblasts and of the smooth muscle cells were labeled in all the organs studied. These preliminary observations suggest that there is a stage in the reproductive cycle in which progesterone receptors are contained in the stromal cells of the oviduct but are absent in the epithelium.
Vesicle numerical densities and cellular attenuation: Comparisons between endothelium and epithelium of the alveolar septa in normal dog lungs
Authors: DeFouw David O. 
Published: February 2005

AbstractThe alveolar septa are divided into two anatomically distinct portions: The thin sides consist of capillary endothelium, alveolar epithelium, and their closely apposed (often fused) basal laminae; the thick sides are characterized by prominent interstitial spaces, containing fibrils and cells, which separate the respective basal laminae. Vesicle numerical densities are comparable (approximately 400 vesicles/μm3 cytoplasm) in the endothelial and epithelial cells on both sides of the septa. Mean vesicle diameters, however, are substantially less in the epithelial cells on both the thin and thick sides. The extent of both endothelial and epithelial attenuation is significantly greater on the thin sides of the septa. Further, epithelial attenuation is more marked than endothelial attenuation on both sides of the septa. The attenuated cellular portions, possibly because of their extreme thinness, are void of vesicles but provide relatively short diffusion distances (20–30 nm) from vessel or alveolar lumen to the basal lamina. Whether these structural differences between endothelial and epithelial cells contribute to physiologic evidence that describes the endothelium as more permeable than the epithelium remains to be established.