bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning electron microscopic examination of human pulonary capillaries using a latex replication method
Authors: Kendall Michael W. , Eissmann Edward 
Published: February 2005

AbstractThe human pulmonary microvasculature from the apical bronchopulomanary segment was studied by scanning electron microscopy using latex relpicas. The latex replica was composed of a blend of vinyl chloride latexes using a plasticized vinyl chloride copolymer with a vinyl chloride copolymer. The polymerized latex produced a cast of the pulmonary arterial vascular tree, including the capillary patterns, which freely anastomose, thereby draining blood into pulmonary veinules and veins. The latex was injected via a gravity flow system modified from its earlier application in Guinea pig lungs. The apparently normal lungs from two recently deceased humans (dead for 5‐6 hours and held in refrigeration) were perfused with heparinized Ringer's solution and subsequently injected with latex. The resulting latex casts of the capillaries revealed a three‐dimensional network arranged in irregular vascular rings or ovals. This patterns was most conspicuous in deep and intermediate bronchopulmonary segmental areas. However, the subpleural capillaries produced casts that often terminated blindly, as observed with stereo SEM, suggesting that these vessels may tend to form thrombi more easily as compared with capillaries from other regions of the lung alveoli. The pulmonary arteriolar replicas contained indentations representing endothelial cell nuclei, and the capillary replicas projected oval evaginations that may represent discrete loci or capillary mural attenuations.
Surface area ratios. III. A stereological method for estimating relative changes in average hepatocytes
Authors: Bolender Robert P. 
Published: February 2005

AbstractStereological information seems to be most interpretable, with respect to experimental changes, when related to an average cell. Current methods for obtaining an average cell volume essentially consist of dividing an aggregate volume of cells by the number of nuclei therein, assuming one nucleus per cell (Loud, ′68). Hepatocytes represent a somewhat special case, however, in that some are binucleated. Since the number of hepatocytes in one cm3 of tissue is less than the number of hepatocyte nuclei in the same cm3, dividing the hepatocytic volume by the number of nuclei gives only an average “mononuclear” hepatocyte. Such an estimate creates two interpretation difficulties: (1) the volume of an average mononuclear hepatocyte is less than that of an average hepatocyte; and (2) changes in the proportion of binucleated cells may compromise the “relative comparisons” for which the method was originally intended. The purpose of this study is to describe a new approach that can avoid these difficulties altogether, and then to assess the errors associated with the average mononuclear hepatocyte estimates. This was accomplished by combining a surface area ratio method, which can detect average cell changes without being influenced by binucleated cells, with the method of Loud (′68), which is affected as described above. The experimental model was the rat liver (n = 20) recovering for 3 days from 5 daily injections of sodium phenobarbital (100 mg/kg). The results indicate that changes in the average cell volumes for the two methods have similar slopes, but by not accounting for binucleated cells, the average mononuclear hepatocyte reference overestimates average hepatocytic volume changes by 63.1%. Similarly, the mononuclear hepatocyte reference overestimates changes in the surface areas of the ER by 32.1% (range = 26.1% to 39.1%), the SER by 21.6% (range = 14.3 to 30.1%), and the RER by 65.1% (range = 54.6% to 76.4%).
Developing innervation of the chick heart: A histofluorescence and light microscopic study of sympathetic innervation
Authors: Kirby Margaret L. , McKenzie John W. , Weidman Thomas A. 
Published: February 2005

AbstractThe available descriptions of the development of sympathetic innervation of the chick heart conflict with the known sympathetic innervation of the adult chicken heart. The adult heart is innervated by bilateral sympathetic cardiac nerves originating from the first thoracic sympathetic ganglia. These nerves travel lateral and anterior to the lung and join the vagi just before entering the pericardium along the great vessels. Using catecholamine histofluorescence techniques and silver preparations, we have observed the development of the sympathetic cardiac nerves. The sympathetic cardiac nerves arise from the first thoracic sympathetic ganglia on the 7th day of incubation. They grow lateral and then ventral to the developing lungs to join the vagi, and are found in the bulbar region of the heart and atrium on the 10th day of incubation. Fluorescent cells without processes mark the course of the sympathetic cardiac nerves and are present in the bulbar region on the 10th day and thereafter. Sympathetic ganglion cells lose their fluorescence between day 8 and day 16 of incubation. This is presumably due to dilution of the transmitter in the rapidly increasing volume of cytoplasm in the sprouting neurons. Small intensely fluorescent (SIF) and adrenal medullary cells do not undergo a diminution of fluorescence during this period. SIF cells appear well differentiated at 16 days.
The dependent and independent relationships between cytodifferentiation and morphogenesis in developing salivary gland secretory cells
Authors: Cutler Leslie S. 
Published: February 2005

AbstractThe mesenchymal capsule was removed from the epithelial anlage of 15 day (unbranched) and 16 day (initially branched) fetal rat submandibular gland (SMG) rudiments. The undifferentiated epithelial portion of the SMG rudiments was placed in tissue culture and examined by light and electron microscopy and histochemistry for secretory peroxidase. The 15 day fetal SMG epithelial rudiments failed to attach, and spread over the culture dish and degenerated by 3 days in culture. The 16 day epithelial rudiments attached to the dish and the cells spread radially from the explant. Mitotic activity was minimal. Cells spreading from the 16 day rudiments underwent cytodifferentiation, giving rise to two secretory cell types: (1) peroxidase containing “proacinar cells,” and (2) secretory “terminal tubule” cells. The results suggest that in the developing SMG, morphogenesis and cytodifferentiation are partially coupled but independently regulated processes. The earliest phases of morphogenesis (rudiment down growth and primary branching) seem to be required to initiate cytodifferentiation. Once initiated, cytodifferentiation can proceed in the absence of continued morphogenesis (tissue organizatation) or significant amounts of connective tissue elements.
The effect of short term incubation in vitro on the RNA content of regenerating mouse epidermis
Authors: Tormay Margaret Anne , Argyris Thomas S. 
Published: February 2005

AbstractThe effect of short term incubation in vitro on RNA content in regenerating and normal epidermis has been investigated. Regenerating mouse epidermis was incubated for three hours, either attached to its underlying dermis or by itself, in either buffered sucrose or Roswell Park Memorial Institute culture medium at 26°C or at 37°C. There is a significant loss of RNA when regenerating epidermis is incubated without being attached to its underlying dermis, at either 26°C or 37°C, although there was little loss of DNA, good incorporation of (3H) orotic acid into RNA, as well as good preservation of epidermal histological details. In contrast, when regenerating epidermis was incubated attached to its dermis, little loss of RNA occurred. Similarly, incubating normal epidermis attached to its dermis results in no loss of RNA. These conditions also result in no significant loss of DNA, good incorporation of (3H) orotic acid into RNA, and preservation of epidermal histological details.
The visualization of myosatellite cells in normal and denervated muscle: A new light microscopic staining technique
Authors: Larocque Alan A. , Politoff Alberto L. , Peters Alan 
Published: February 2005

AbstractA new light microscopic staining technique allows the visualization of satellite cells on the surface of myofibers. Either prior to or during fixation, whole frog sartorius muscles are bathed in an acidic buffered solution containing lead nitrate and subsequently exposed to ammonium sulfide. The staining of the satellite cells resulting from this procedure reveals their positions, and the outlines of their cell processes which occasionally branch. Electron microscopy shows that the staining is due to lead deposits localized between apposing membranes of satellite cells and associated myofibers. Prior exposure to N‐ethyl‐maleimide (NEM) does not alter the formation of the lead deposits on the satellite cell, but reduces the amount of Pb deposits on the muscle surface and connective tissue.This technique has been applied to determine the effects of denervation on the satellite cells of frog sartorius muscles. Four weeks after denervation, the number of satellite cells is essentially the same in both denervated muscles and the intact muscles of the contralateral side. However, denervation results in a subpopulation of satellite cells with altered shapes. They have elongated cytoplasmic processes which often branch. It is suggested that these supernumerary cytoplasmic processes represent an intermediate phase in the transition of satellite cells to myoblasts.
Three large dissectable rat glomerular models reconstructed from wide‐field electron micrographs
Authors: Yang Grace C. H. , Morrison Ashton B. 
Published: February 2005

AbstractThree very large styrofoam models of glomerular capillary tufts have been built, based on serial ultrathin sections which cut through three complete rat glomeruli isolated from all regions of renal cortex. The images of glomeruli are enlarged on 20" × 24" wide‐field electron micrographs, from which each capillary is traced on styrofoam discs and then individually connected. These models can be disassembled to measure the width and length of each capillary segment and to map the complicated glomerular vascular arrangement. Each of the three randomly selected glomeruli has three arteriolar openings passing through the Bowman's capsule–‐e.g., an afferent opening and two closely situated efferent openings. Each of the three glomeruli consists of three major lobules, e.g., two larger lateral lobules and a smaller central lobule. Assuming the model is positioned so that the vascular pole is superior and the afferent arteriole is closer to the observer than the two efferent vessels, the lobule occupying the frontal right portion originates from the right major branching of the afferent arteriole and reconverges at the right efferent opening. The lobule occupying the frontal left portion originates from the left major branching of the afferent arteriole and reconverges at the left efferent opening. The lobule occupying the central portion originates from the central major branching and connects both lateral lobules with a few interlobular anastomoses. The diameter and the length of interlobular anastomoses, and the volume of major lobules are listed. The technique of the isolation and reembedment of glomeruli and the construction of models is described in detail.
Presynaptic bodies of auditory hair cells in old world monkeys
Authors: Bodian David 
Published: February 2005

AbstractPresynaptic bodies of auditory hair cells of Old World monkeys are separately differentiated in inner, as contrasted with outer, hair cells. The pre‐synaptic bodies of outer cells are spherical and of variable electron density, and are thus similar to those of the labyrinth of vertebrates from fish to man. The difficulty in finding them, as compared with the relative ease of finding the presynaptic bodies of inner hair cells, suggests either that they are not present in all outer hair cells or that they undergo a regression‐reconstitution cycle. The presynaptic bodies of simian inner hair cells are almost always ring‐shaped. The few exceptions reinforce the impression of a later evolutionary development of the inner hair cell system. In any event, our findings serve to reemphasize the remarkable differentiation of outer and inner hair cell systems, and to deepen the mystery of their separate roles in audition.
Histology of the canine uretha II. Morphometry of the male pelvic urethra
Authors: Cullen W. Craig , Fletcher Thomas F. , Bradley William E. 
Published: February 2005

AbstractUrinary bladders and pelvic urethrae were collected from six adult and two juvenile male dogs. Within two vesical and six urethral sampling regions, volume densities were estimated for smooth and striated muscle, connective tissue and elastic fibers, stratum cavernosum, luminal epithelium, and prostate. The neck had significantly less smooth muscle and more connective tissue than the body of the bladder. In the prostatic urethra, smooth muscle was associated principally with trabeculae surrounding prostate lobules. Smooth muscle was sparse superficially in the prostatic capsule and practically absent in relation to the mid‐prostatic urethra. Thus there was no mechanism for active closure of the middle prostatic urethra, and elastic fiber density was correspondingly high in this region. The smooth muscle sphincter needed to maintain urinary continuence and prevent semen reflux was primarily the vesical neck. Caudal to the body of the prostate, striated muslce comprised more than 50% of the urethral wall. Juvenile and adult postprostatic urethrae were similar except for a decreased quantity of stratum cavernosum in the pups.
Foetal haemopoiesis during the hepatic period. I. Relation between in vitro liver organogenesis and erythropoietic function
Authors: Nessi Analía C. , Bozzini Carlos E. , Tidball Morris V. 
Published: February 2005

AbstractCultures of the hepatic bud, under different experimental conditions, show a direct relation between foetal age at the time of dissection and the further organogenesis of the explant. In cultures of the septum transversum plus hepatic bud—with or without splanchnic mesenchyme—obtained from embryos of four to 25 somites, the capacity of endodermic cells to differentiate into hepatocytes appears only in a small number of samples; whereas, in the hepatic bud from older embryos (26 to 40 somites), this differentiation occurs in all cases.The amount of time cultures were allowed to grow was important for hepatic organogenesis, as measured by cord‐like organization of hepatocytes plus their storage capacity for glycogen. The possibility of the explants showing complete haemopoiesis was also a condition of foetal age at the time of explant. Haemopoiesis was not found in cultures from embryos of less than 25 somites. On the other hand, development of haemopoiesis did not show a direct relation to days of culture, since the peak of this activity was observed towards the third day in vitro. Most explants showed a generalized haemopoiesis (both interstitial and vascular) with a decay towards the sixth day.Endodermal cells of the hepatic bud were capable of both proliferation and differentiation into hepatocytes, even in those mesenchymes considered inadequate such as limb mesenchyme. In the latter case we were unable to find haemopoiesis at any time. The septum transversum, when cultured alone, did not contain haemopoietic cells.
The oculomotor nucleus and extraocular muscles in a mutant anophthalmic mouse
Authors: Paterson J. A. , Kaiserman‐Abramof I. R. 
Published: February 2005

AbstractThe object of this study was to determine whether the oculomotor nucleus and the extraocular muscles are present in the adult of a mutant mouse strain in which eye formation fails early in development (Chase and Chase, '41). Neuronal counts for the oculomotor (IIIrd) nucleus were obtained from serial paraffin sections made through the midbrains of seven mice of the anophthalmic mutant group (ZRDCT‐An) and seven mice of the same strain in which eyes were present (ZRDCT‐N). The orbital structures of the anophthalmic and control groups were reconstructed from 1‐μm plastic serial sections. There was in the anophthalmic mouse, in the same location as in the normal, an oculomotor nucleus whose mean neuronal cell number was 206 (± 40). The normal mouse had a mean value of 262 (± 63) oculomotor neurons. On the basis of these results, this difference between the two groups was not statistically significant (P = 0.073). The neuronal number per cubic millimeter was similar in the two groups (P = 0.81). In the orbit of the anophthalmic mouse, several bundles of striated muscle occupied a location comparable to that of extraocular muscle in the normal mouse. Neuromuscular junctions were present on fibers of this orbital muscle. It is concluded that the early failure of eye formation does not prevent the development of extraocular muscles and the oculomotor nucleus, and their retention in the adult.
Immunoshistochemical localization of gonadortropin releasing hormone (GnRH) in the bovine hypothalamus and infundibulum
Authors: Dees W. L. , McArthur N. H. 
Published: February 2005

AbstractNeural structures containing gonadotropin‐releasing hormone (GnRH) in the bovine brain and infundibulum were characterized by light microscopic immunohistochemistry. GnRH‐positive perikarya were localized singly or in small groups within the infundibular nucleus and were seen grouped in large discrete clusters within the ventromedial nucleus. Positive axons were localized within the brain from the nucleus of the rostral commissure to the medial mammillary nuclei, and in specific areas of the infundibulum and infundibular stalk.
The effects of the carcinogen, 1,2‐dimethylhydrazine, on turnover 3H‐thymidine labeled cells from mucosal glands of mouse colon
Authors: Richards Thomas C. 
Published: February 2005

Abstract1,2‐dimethylhydrazine (DMH), administered weekly to mice for 20 weeks, induces tumors in the distal segment of colon. Tumors are preceded by enlargement of the mucosal glands resulting from increases in the number of total cells and 3H‐thymidine labeled cells/crypt. Cells located in the crypt base normally undergo 2–3 divisions as they migrate toward the lumen, and they become post‐mitotic in the upper crypt. It is not known if cells in these eniarged crypts have rates of turnover similar to cells in normal crypts. Groups of w/s female mice were treated with DMH (20 mg/kg body wt) for 3,8, or 16 weeks; controls were given 0.001 M EDTA. After treatment, the animals were injected with 3H‐thymidine and killed one hour or 1,2,4,7 or 17 days later. Autoradiographs were prepared from sections of distal colon. The total cells/crypt column in 30 crypts/animals were counted. Crypts were divided into 10 equal segments based on the crypt length and the labeled cells/segment were counted. The relative number of labeled cells and the distribution of these cells within crypts were similar in DMH‐treated and control animals after one hour. However, as the cells migrated toward the lumen, the number of labeled cells doubled after 2 days and tripled after 4 days in DMH‐treated animals but only doubled during the 4 days in controls. This difference was caused by retention of an increased number of dividing cells in the lower 4 segments of the crypts and suggests an increase in those cells that divide twice. In addition, increased numbers of labeled cells were retained in the upper 3 segments of DMH‐treated animals after 4 days. These findings indicate that the crypt cells of DMH‐treated animals are generally more immature than those of controls and this immaturity contributes to the enlargement of mucosal glands during carcinogenesis.
A method for culturing canine tracheal smooth muscle cells in vitro: Morphologic and pharmacologic observations
Authors: Avner Barry P. , Delongo Judi , Wilson Steve , Ladman A. J. 
Published: February 2005

AbstractA method of culturing canine tracheal smooth muscle cells in vitro is described. The morphology of these cells is monitored up to 60 days in culture and selected stages are illustrated. The characteristics of these cells are numerous mechanical attachments, the presence of thick filaments in suitably processed cells, and their contractile response to in vitro administration of carbachol, a cholinomimetic drug. They also possess nexus formations and both thin (actin) filaments and 10‐nm filaments. Mitosis is found in the nonconfluent preparations up to 16 days after culturing. Cultures of 2 to 8 days appear to be most useful as pharmacological test vehicles. This system will be used to explore the phenomenon of adrenergic beta‐2 receptor desensitization in airway smooth muscle, to attempt to localize these receptor sites and to determine how receptor affinity and/or number may be regulating cell response to pharmacologic agents.
The incidence of dentinal tubules containing more than one process in the cuspal dentin of cat canine teeth
Authors: Holland G. R. 
Published: February 2005

AbstractThe incidence of multiple processes within the tubules of the cuspal dentin of the cat's canine has been measured by counting directly from ultrathin sections examined in the electron microscope. The incidence is highly variable. The greatest incidence was found 1 mm below the cuspal dentino enamel junction where up to 75% of tubules in some areas contain more than one process. On average 33.6% of the tubules at this level contain multiple processes. The incidence declines linearly toward the apex with virtually no multiple processes occurring at 4 mm below the tip dentino enamel junction or beyond. Half of the “second processes” contain either mitochondria and/or vesicles. They are restricted to predentin where many of them end and to inner calcified dentin. Their distribution is similar to that described for nerve fibers in other studies. None of the processes participated in specialized junctions.
Cellular composition of the bone marrow in the chicken: II. The effect of age and the influence of the bursa of fabricius on the size of cellular compartments
Authors: Glick Bruce , Rosse Cornelius 
Published: February 2005

AbstractThe blood and bone marrow of New Hampshire chicks were analyzed quantitatively from the time of hatch to 8 weeks of age. Hormonal bursectomy was performed by treating embryonating eggs on the 11th day of incubation with testosterone propionate (TP) which resulted in severe hypogammaglobulinemia and complete atrophy of the bursa of Fabricius. TP‐treated birds exhibited some lymphocytopenia, reduced splenic weight, and lack of plasma cells in their bone marrow. The number of cells per milligram bone marrow was comparable in normal and TP‐treated birds, falling in the range reported for laboratory rodents. The chick medullary hemopoiesis is characterized by the predominance of erythroblasts throughout early development; granulocytes and lymphocytes represent much smaller cellular compartments than in rodents. In the chick granulocytes tend to decrease after hatch, whereas in rodents they tend to increase. The normal chick shows a temporary increase in marrow lymphocytes after hatch, similar to that observed in some young rodents, but on a much smaller scale. Hormonal bursectomy did not prevent the development of a lymphocyte population in the bone marrow. These cells were fewer in TP‐treated birds at hatch and at 4 weeks than in normal birds, but at 8 weeks of age normal and bursectomized chicks had comparable numbers of lymphocytes in their marrow. Although some lymphocytes in avain bone marrow may depend on the bursa of Fabricius for their development, a substantial proportion of bone marrow lymphocytes in the chick are bursa independent. The cell surface phenotype and site of origin of these cells remains to be investigated.