bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early formation of the vascular system in quail embryos
Authors: DeRuiter M. C. , Poelmann R. E. , Mentink M. M. T. , Vaniperen L. , Gittenberger‐De Groot A. C. 
Published: February 2005

AbstractThe relation between vascular development and translocation of the splanchnic mesodermal layers was studied in presomite to 20‐somite quail embryos by scanning electron microscopy. In addition, serially sectioned embryos were stained immunohistochemically with monoclonal antibodies (αQH1 or αMB1) specific for endothelial and hemopoietic cells.By the formation of the foregut the anterior borders of the two splanchnic mesodermal layers of a presomite embryo are translocated to the lateral and ventral sides of the foregut and fuse in the ventral midline of a 4‐somite embryo. Meanwhile the splanchnic mesoderm differentiates into a splanchnic mesothelial layer and a plexus of endothelial cells, facing the endoderm.From 4 somites onward the foregut is covered by a single endothelial plexus. At first the endothelial precursors bordering the anterior intestinal portal and those in the area of the ventral mesocardium lumenize, subsequently giving rise to the endocardium of the heart tube. Hereafter, the pharyngeal arch arteries and the dorsal aortae develop from the remaining precursors. During formation of the pharyngeal arches, the pharyngeal arch arteries maintain their connections with the splanchnic plexus through the developing ventral pharyngeal veins.After disappearance of the dorsal mesocardium, the midpharyngeal endothelial strand, which is a longitudinal strand of proendocardial cells, remains connected to the foregut. This strand will contribute to the formation of the pulmonary venous drainage into the left atrium.A bilateral accumulation of cardiac jelly developing between the promyocardium and proendocardial plexus only suggests that the heart develops from two tubes. The proendocardial layer, however, is not divided by the ventral mesocardium but initially forms just one endocardial heart tube. © 1993 Wiley‐Liss, Inc.
Effects of estradiol and progesterone on the cytodifferentiation of epithelial cells in the oviduct of the newborn golden hamster
Authors: Abe Hiroyuki , Oikawa Taneaki 
Published: February 2005

AbstractThe effects of estradiol and progesterone on the cytodifferentiation of epithelial cells in the oviduct of the newborn golden hamster were investigated by electron microscopy. Consecutive daily injections of estradiol‐17β (E2) induced various ultrastructural changes in undifferentiated epithelial cells of the neonatal oviduct. Ciliogenesis, formation of some ciliary buds, and ciliation were frequently observed in the oviductal epithelial cells on days 1–4 of consecutive treatments with E2. On days 2 and 3, the remaining cells contained well‐developed Golgi apparatus and rough endoplasmic reticulum. Thereafter, a few secretory granules were observed in the cytoplasm of these cells, indicative of differentiation into secretory cells. Occasionally, secretory cells undergoing ciliogenesis or mitosis were found in the epithelium. On day 9, many fully mature ciliated and secretory cells were observed. Quantitative studies clearly showed that E2 induced the differentiation of both ciliated and secretory cells. By contrast, consecutive daily injections of progesterone significantly stimulated the appearance of ciliogenic and ciliated cells but not that of secretory cells. These results indicate that the induction of differentiation of secretory cells is a specific effect of estrogen, whereas the differentiation of ciliated cells may be closely related to effect of progesterone as well as of estrogen. It is suggested that hormonal effects on differentiation differ between ciliated and secretory cells in the oviductal epithelium of the newborn golden hamster. © 1993 Wiley‐Liss, Inc.
Preservation of cardiac myocytes subjected to different preconditions: A comparative morphometric study of beating, fibrillating, and cardioplegically arrested canine hearts
Authors: Schmiedl A. , Schnabel Ph. A. , Richter J. , Mall G. , Bretschneider H. J. 
Published: February 2005

AbstractThis study compares the ultrastructure of beating canine hearts with that of hearts subjected to different clinically common forms of cardiac arrest. The contraction state per test field was ascertained according to a specially developed classification. The volume density of myofibrils and the surface to volume ratio of mitochondria were used as parameters for cellular and mitochondrial swelling. Contraction bands were not found in any of the differently pretreated hearts. Following immersion fixation, contractions as well as over‐ and hypercontractions in beating, fibrillating, and St. Thomas‐arrested hearts are significantly more pronounced than in HTK‐arrested hearts. Cellular and mitochondrial volumes were similar in beating and fibrillating hearts. St. Thomas‐perfusion significantly decreased cellular and mitochondrial volume compared to beating hearts, but these values were in the same range as in fibrillating hearts. Only HTK‐solution actually led to a strong reduction of these compartments. Compared to immersion, perfusion fixation after coronary perfusion with cardioplegic solutions led to comparable cellular volumes, but significantly elevated the percentage of relaxed sarcomeres and significantly reduced mitochondrial swelling. The best structural preservation of myocytes was found after HTK‐perfusion and perfusion fixation. Such ultrastructural quantitative and morphometrical parameters are powerful tools since results confirm that the degree of myocardial preservation depends on the method of cardiac arrest. This forms the basis for the choice of preconditions for subsequent ischemia. Furthermore, significant alterations of myocardial ultrastructure depend on a combination of the functional state of the heart, the method of cardioplegia, and the technique of fixation. © 1993 Wiley‐Liss, Inc.
Parenchymal cell proliferation and mechanisms for maintenance of granular duct and acinar cell populations in adult male mouse submandibular gland
Authors: Denny Paul C. , Chai Yang , Klauser Donna K. , Denny Patricia A. 
Published: February 2005

AbstractTo evaluate proliferation as a factor in maintenance of parenchymal cell populations in adult male mouse submandibular glands, a variety of surveys were conducted following a pulse with 3H‐thymidine. Striated granular duct (SGD) cells had the highest labeling index, followed by intercalated duct (ID) cells, then acinar (AC) cells, and granular duct (GD) cells had the lowest. These cell types showed from 30% to 60% completion of mitosis by 24 hr, with SGD, AC, and GD showing a likely second wave of mitosis sometime between 2 and 7 days after the pulse. About 40% of the pulse‐labeled cells still remained as single cells at 42 days after the pulse. Repeat divisions in daughter cells of the primary labeled cells were very rare. A shift in the pattern of labeled cells at the ID‐GD junction indicates that ID and SGD cells in this compartment are differentiating to GD cells. Further comparison of the magnitude of this conversion with the amount of noncompartmental GD cell proliferation provided a basis for calculating that ∼70% of GD cell population maintenance occurs by selfproliferation, and the remaining 30% is contributed by differentiation from ID and SGD cells. A similar survey at the ID‐acinus junction showed no evidence of conversion of ID cells to AC cells indicating that most, if not all, proliferative activity leading to AC cell population maintenance occurs by self‐proliferation. Finally, based in part on structural changes at the ID‐GD junction during the survey period, a pattern of cell conversion described as “in situ differentiation” is proposed. When this pattern is carried to fruition, this explains several structural features of the secretory complex typical to the male pattern submandibular gland. The proposed mechanism is supported by a three‐dimensionally reconstructed sequence of likely intermediate structures. © 1993 Wiley‐Liss, Inc.
Establishment of heterogeneity among blood vessels: Hormone‐influenced appearance of hepatic lipase in specific subsets of the ovarian microvasculature
Authors: Hixenbaugh Elizabeth A. , Strauss Jerome F. , Paavola Laurie G. 
Published: February 2005

AbstractWe used biochemical and structural approaches to analyze the influence of gonadotropic hormones on the association of hepatic lipase with specific subsets of ovarian blood vessels. Western blotting was used to detect this enzyme in effluent collected from heparin‐perfused ovaries of nonhormone‐treated immature rats and those primed with pregnant mare's serum gonadotropin (PMSG) alone or in combination with human chorionic gonadotropin (hCG). The effects of these hormones on hepatic lipase distribution among oyarian blood vessels was assessed before and after hCG and/or PMSG treatment by immunofluorescence and immunogold cytochemistry. For the latter, immunoreagents and fixative were delivered directly to chilled, unfixed ovaries by in situ vascular perfusion. Data from biochemical and structural analyses indicated that hepatic lipase was absent from nonhormone‐treated ovaries. As shown by Western blotting of ovarian effluent, the enzyme appeared following treatment with PMSG and PMSG‐hCG; it increased in amount in a time‐dependent manner, with a transient decline in the early hours after hCG injection. Enzyme levels paralleled growth and vascularization of follicles and corpora lutea; the fall tended to coincide with early events in luteal angiogenesis. Immunogold microscopy showed that hepatic lipase was abundant in thin‐walled blood vessels of theca interna of follicles, corpora lutea, and interstitial cells but sparse in those of the stroma. Moreover, during neovascularization of differentiating corpora lutea, vascular sprouts arising from hepatic lipase‐laden thecal vessels appeared to lose, then regain, the enzyme as development progressed. Our findings thus suggest (1) that hormones influence the establishment of endothelial cell heterogeneity within the microvasculature of a single organ and (2) that development of novel endothelial cell properties in specific subsets of blood vessels underlies compartmentalization of function within a tissue. © 1993 Wiley‐Liss, Inc.
Stage‐Dependent changes in spermatogenesis and sertoli cells in relation to the onset of spermatogenic failure following withdrawal of testosterone
Authors: Kerr J. B. , Millar M. , Maddocks S. , Sharpe R. M. 
Published: February 2005

AbstractRapid and complete withdrawal of intratesticular testosterone was achieved via the destruction of all Leydig cells with the specific Leydig cell cytotoxin ethane dimethanesulphonate (EDS). Restoration of testosterone levels was accomplished by administration of a single dose (25 mg) of testosterone esters (T) known to reverse the antispermatogenic effects of androgen withdrawal. Quantitation of the degenerating germ cells in cross sections of seminiferous tubules (ST) at stages IV–V, VII, IX, and X–XI of the spermatogenic cycle was used as a sensitive biological index of the effects of testosterone withdrawal and restoration upon the function of the Sertoli cells. Compared to control testicular tissues, the mean numbers of pyknotic germ cells per ST cross section at stages VII, IX and X–XI increased significantly (P < 0.01–0.001) between 4 to 8 days post‐EDS treatment, but only in stage VII tubules was this trend reversed significantly (P < 0.005) within 2 days by T supplementation. In EDS‐treated rats, stages VII, VIII, IX, and X‐XI also exhibited significant (P < 0.05–0.001) increases (compared to controls) in the volumetric proportions by which intraepithelial vacuoles appeared within the seminiferous tubules. Again, in EDS+T supplemented rats, the appearance of vacuoles was significantly (P < 0.001) suppressed in stage VII and VIII. In contrast to tubules at stages VII‐XI, those at stages IV–V were completely unaffected by testosterone withdrawal or replacement. The results show that at selected time intervals after EDS treatment, testosterone supplementation is capable of preventing/reversing these morphological changes within 2 days in stage VII tubules. It is suggested that the induction and subsequent prevention of seminiferous epithelial damage will serve as an important in vivo and in vitro approach for studies on the androgen‐mediated changes in Sertoli cell biology during phases of impairment and recovery of their function. Manipulation of adult Sertoli cell function as provided by our model should permit identification of androgen‐regulated gene products together with an understanding of their role(s) in normal and abnormal spermatogenesis. © 1993 Wiley‐Liss, Inc.
An overview of culture and isolation methods suitable for in vitro studies on pulmonary neuroendocrine cells
Authors: Speirs Valerie , Cutz Ernest 
Published: February 2005

AbstractSuccessful isolation and culture of pulmonary neuroendocrine cells (PNEC) is essential for the investigation of cellular and membrane properties of these cells. Such studies are important to define the functional role for PNEC but are hampered by their scant numbers and widespread distribution within the pulmonary epithelium. Several in vitro methods for the isolation and culture of these cells have been described over the past decade, including organ culture, isolation of single cell suspensions enriched for PNEC, and immunomagnetic cell separation techniques. This paper reviews the various methods and discusses their advantages and pitfalls. © 1993 Wiley‐Liss, Inc.
Cell biology of pulmonary neuroepithelial bodies—validation of an in vitro model. I. Effects of hypoxia and Ca2+ ionophore on serotonin content and exocytosis of dense core vesicles
Authors: Cutz Ernest , Speirs Valerie , Yeger Herman , Newman Charlotte , Wang Dashou , Perrin Donald G. 
Published: February 2005

AbstractPulmonary neuroendocrine (NE) cells including the innervated clusters of NE cells—neuroepithelial bodies (NEB)—are difficult to study because of their small numbers and diffuse distribution within the airway mucosa of the lung. We have previously reported a method for isolation and culture of NE cells from rabbit fetal lung using a combination of mechanical and enzymatic dissociation followed by gradient centrifugation. This method provides single cell suspension of mixed lung cells enriched in NE cells, particularly those originating from NEB.This study further validates our in vitro model by detailed morphologic characterization of cultured NEB cells using high resolution light microscopy, transmission and scanning electron microscopy, HPLC for detection of serotonin (5‐HT), and molecular (Northern blot) analysis of mRNA encoding for 5‐HT synthesizing enzymes, tryptophane hydroxylase, and aromatic L‐amino acid decarboxylase. In addition to effects of hypoxia on NEB cells in vitro were investigated to define the role of these cells as possible airway chemoreceptors. Exposure of NEB cultures to hypoxia resulted in decreased intracellular content of 5‐HT accompanied by increased exocytosis of dense core vesicles (DCV). The amount of 5‐HT release correlated with the degree of hypoxia, suggesting modulation by ambient pO2 levels. The role of Ca2+ ions in exocytosis of DCV and 5‐HT release from NEB cells was tested in experiments with Ca2+ ionophore (A23187). Exposure of cultures to 5 μg/ml of ionophore resulted in up to 40% reduction in 5‐HT content of NEB cultures as well as increased exocytosis of DCV.Our overall findings are consistent with a view that NEB cells are chemosensory in nature and that Ca2+ signaling pathway is involved in stimulus‐secretion coupling. Further refinements in cell separation and culture methodology are required before more detailed investigation of NEB cell membrane properties, signal transduction mechanisms, and intracellular signaling pathways can be carried out. © 1993 Wiley‐Liss, Inc.
Neuroendocrine cell populations in postnatal human lungs: Minimal variation from childhood to old age
Authors: Gosney John R. 
Published: February 2005

AbstractAlthough changes in the human pulmonary neuroendocrine system have been described in association with a variety of pulmonary disease, little is known of how the system changes with age in healthy lungs. As delineated by their immunoreactivity for neuron‐specific enolase, protein gene product 9.5 and chromogranin A, the density of the system's component cells in terms of the rest of the pulmonary epithelium varied minimally between 10 groups of subjects divided according to age and ranging from children to nonagenarians, figures for the groups varying only between 2.91 and 4.19 neuoendocrine cells per 10,000 epithelial cells. In only three subjects were neuroendocrine cells found in the parenchyma; the vast majority were located in airways with about 65% in bronchi. Cells were more often arranged in the form of clusters in the younger subjects than in the elderly, in whom clusters were extremely rare, but the significance of this observation is unclear. © 1993 Wiley‐Liss, Inc.
Calcium and ionophore A23187 lower calcitonin gene‐related peptide‐like immunoreactivity in endocrine cells of organ cultured fetal rat lungs
Authors: Ebina Masahito , Hoyt Richard F. , Sorokin Sergei P. , McNelly Nancy A. 
Published: February 2005

AbstractSmall‐granule endocrine cells differentiate in airway epithelium of intact and cultured fetal rat lungs. We noted that the cells store calcitonin gene‐related peptide (CGRP) in vitro as well as in vivo and used the ionophore A23187 to test the effects of calcium on peptide secretion in this system. Lungs of 14‐day and 15‐day fetal rats, organ cultured for 6–9 days, were divided into groups of 5 explants each and incubated for 15 min at 37°C in the basic medium containing 0 mM, 1 mM, or 10 mM CaCl2, with or without 8 μM A23187, or 10 mM EGTA. Intracellular CGRP in these explants was quantified by supraoptimal dilution peroxidase immunocytochemistry (Springall et al.: J. Pathol. 155:259–267, 1988): counts were made of endocrine cells stained with a 1/60,000 dilution of anti‐CGRP and repeated on the same sections after restaining with antibody diluted at 1/1,000. Results, analyzed by Chi‐square test, were expressed as % cells stained with antibody at 1/60,000 vs. those stained at 1/1,000. Immunoreactivity for CGRP was significantly reduced by A23187 in the presence of high extracellular Ca2+ (10 mM), the inference being that these cells secrete peptide hormones in response to Ca2+ influx across the plasma membrane. The organ cultures evidently can be used to assess certain physiological responses of lung endocrine cells in an accessible, relatively organotypical setting. © 1993 Wiley‐Liss, Inc.
Dynamics of epithelial cells in the corpus of the mouse stomach. III. Inward migration of neck cells followed by progressive transformation into zymogenic cells
Authors: Karam Sherif M. , Leblond Charles Philippe 
Published: February 2005

AbstractThe neck cells (or mucous neck cells) present in the neck region and the zymogenic cells (or chief cells) present in the base region of the units in the mouse corpus were examined in the electron microscope (EM) and in radioautographs prepared after administration of 3H‐thymidine by single or multiple injections or by continuous infusion for 1–52 days. For these studies, the neck region of the units has been subdivided into three equal segments, respectively named high neck, mid neck, and low neck, while the base region has been similarly subdivided into high base, mid base, and low base.The neck region includes an average of 12.6 neck cells, characterized in the EM by dark, mucous secretory granules that frequently exhibit a light, pepsinogenic core. Continuous 3H‐thymidine infusion reveals that neck cells come from pre‐neck cells, which are believed to arise in the isthmus region from the undifferentiated granule‐free cells through a pre‐neck cell precursor stage. The pre‐neck cells, characterized by the presence of a few cored secretory granules, migrate inward (i.e., in the direction of the blind end of the units) and enter the neck region to become neck cells. It is estimated that 59% of the neck cells arise from differentiation of pre‐neck cells, whereas the other 41% are derived from their own mitoses. Neck cells migrate inward in 1–2 weeks from the high through the mid and low neck segments, while they keep on producing more and larger secretory granules and thus further differentiate as mucus‐producing cells.When neck cells reach the high base segment, they become pre‐zymogenic cells that produce secretory granules in which appear light, irregular, pepsinogenic patches which encroach on the dark mucous content. With time, the pre‐zymogenic cells, of which there are 5.0 per unit on the average, keep on producing new granules with larger and larger light patches, so that in the end the cells produce granules which are entirely filled by light, pepsinogenic material. At this stage, the cells are zymogenic cells.Zymogenic cells, which average 67.5 per unit, further migrate inward, while gradually enlarging and producing pepsinogenic granules of increasing size. In the low base segment, some zymogenic cells show signs of degeneration leading to death by either necrosis or apoptosis. While remnants of the necrotic cells appear to be released to the unit lumen, the apoptotic cells are phagocytosed by a neighboring zymogenic cell or by a connective tissue macrophage breaking through the basement membrane of the oxyntic unit.Briefly, the zymogenic cell lineage, a cell sequence initiated from the stationary undifferentiated granule‐free cells, includes pre‐neck cell pre‐cursors, pre‐neck cells, neck cells, pre‐zymogenic cells, and finally zymogenic cells, which all migrate in the direction of the unit's blind end, near which zymogenic cells are lost. © 1993 Wiley‐Liss, Inc.
Dynamics of epithelial cells in the corpus of the mouse stomach. V. Behavior of entero‐endocrine and caveolated cells: General conclusions on cell kinetics in the oxyntic epithelium
Authors: Karam Sherif M. , Leblond Charles Philippe 
Published: February 2005

AbstractEntero‐endocrine cells and the rare cells named caveolated or brush cells have been examined in light microscopic radioautographs of the mouse corpus after various periods of continuous 3H‐thymidine infusion. Moreover a search for immature forms and mitoses of these cells was undertaken in the electron microscope.Entero‐endocrine cells are present in the four regions of the epithelial units, but their number is low in the pit, intermediate in the isthmus and neck, and high in the base. The labeling pattern after continuous 3H‐thymidine infusion indicates that these cells are produced in the isthmus from undifferentiated granule‐free cells presumed to be the stem cells of the epithelium, and may retain a limited ability to divide. A few of the newly formed entero‐endocrine cells migrate to the pit, but the majority goes to the neck and, from there, to the base where they are present in relatively high numbers.Little information is available on the dynamics of caveolated cells. Since immature forms are present in the isthmus and mature ones in the other regions, it is concluded that they arise in the isthmus and migrate away in both directions.Finally, concluding remarks are presented on the kinetics of each one of the cell lineages described in this and the four previous articles. © 1993 Wiley‐Liss, Inc.