bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface architecture of the mucosal epithelium of the cat trachea: I. Cartilaginous portion
Authors: Tandler Bernard , Sherman James M. , Boat Thomas F. 
Published: February 2005

AbstractThe mucosal covering of the cartilaginous portion of the cat trachea was studied by correlated light, transmission‐electron, and scanning‐electron microscopy. While in some areas the ciliated pseudostratified epithelial lining is fairly smooth in contour, in other areas it contains longitudinally oriented, cilia‐lined clefts. Ducts from submucosal glands sometimes open into the base of these clefts, or into funnel‐shaped stomata that are lined by either ciliated or microvillus‐rich cells. Specialized epithelial cells are occasionally associated with the clefts or with other regions of surface epithelium. In single sections, these cells appear to contain a cilium‐lined vacuole, but serial sectioning has demonstrated that these apparent vacuoles actually are long intracellular inaginations in enormously elongated cells that extend longitudinally in the plane of the epithelium. The function of these cells is undetermined. Basal cells are attached to the lamina densa by means of hemidesmosomes that consistently lack peripheral densities; in contrast, the tall columnar cells have no hemidesmosomes.
Development and melatonin content of the deep pineal gland in the syrian hamster
Authors: Sheridan Michael N. , Rollag Mark D. 
Published: February 2005

AbstractThe morphological relationships between the superficial and deep pineal glands of neonatal Syrian hamsters are described at both light and electron microscopic levels. In addition, melatonin contents in the two glandular masses are compared throughout a 14 hr light:10 hr dark photoperiod in 20‐day‐old hamsters. It has been found that the pineal anlage begins to separate into deep and superficial components between the first and third postnatal days of life. Separation is usually complete by day 12. The fine structure of the deep gland is similar to that of the superficial gland throughout development. By the time of weaning (20 days of age), the young hamsters exhibit distinct nighttime elevations of melatonin in both the superificial and deep glands, the quantities in the deep gland being approximately 5% those of the superficial pineal. Like that of the superficial pineal, the rise in deep pineal melatonin content can be abolished by exposure of hamsters to light.
Light and electron microscopic cytochemistry of glycoconjugates in the rectosigmoid colonic epithelium of the mouse and rat
Authors: Thomopoulos G. N. , Schulte B. A. , Spicer S. S. 
Published: February 2005

AbstractThe several cell types in mouse and rat rectosigmoid colon have been examined with light and electron microscopic methods for localizing and characterizing complex carbohydrates. Mucous cells, also termed vacuolated cells, and goblet cells comprised most of the deep crypt epithelium in both species, and absorptive columnar cells and goblet cells mainly populated the more superficial epithelium of the upper crypts and main lumen. Occasional tuft cells and enteroendocrine cells were also encountered.Transitional cells structurally intermediate between mucous cells and absorptive cells contained granules characteristic of mucous cells and vesicles like those of columnar absorptive cells. These intermediate cells supported the concept of replacement of mucous by absorptive cells through transformation of mucous into absorptive cells. The intermediate cells also contained numerous lysosomes often in apparent fusion with mucous granules, indicating crinophagic disposal of mucous granules as a mechanism in the cell transformation. Glycoconjugate in absorptive cell vesicles resembled that coating the apical plasmalemma and appeared to represent the source of the glycocalyx of the brush border. Complex carbohydrate in these vesicles differed cytochemically from that of the mucous cell granules, which release their content into the crypt lumen. The absorptive cell vesicles, therefore, constitute an organelle distinct from the mucous cell granules rather than an atrophic form of the latter in a more mature cell.Goblet cells differed in failing to transform morphologically with age but changed in the cytochemical characteristic of their secretion during migration up the crypts. Terminal N‐acetylglucosamine residues diminished, while terminal sialic acid‐galactose dimers increased during the upward migration, indicating activation of glycosyl transferase synthesis in relation to goblet cell maturation.Glycoconjugate in secretion of mucous cell granules differed markedly from that in goblet cell granules, and content of both organelles differed from that of absorptive cell vesicles. However, secretion in mucous cell granules appeared generally similar for mice and rats with minor exceptions, and secretion in goblets of mice generally resembled that in goblets of rats. Cells interpreted tentatively as Kulchitsky cells stained for high content of fucose with the Ulex europeus I lectin. Globoid leukocytes infiltrating the epithelium of the rat but not the mouse rectosigmoid colon resembled globoid leukocytes in rat tracheal epithelium and, like the latter, appeared to derive from mast cells.
Chronobiology of the intestinal tract of the mouse
Authors: Scheving L. E. , Tsai T. H. , Scheving L. A. 
Published: February 2005

AbstractThis paper summarizes recent and continuing work on circadian rhythms in the alimentary tract of rodents; these include: (1) cell proliferation, (2) activities of intestinal enzymes, and (3) behavioral aspects of spontaneous feeding and drinking. All regions of the intestinal tract show marked circadian behavior in cell proliferation. The roles of the light‐dark cycle and meal timing in synchronizing such rhythms are discussed as well as the influence of epidermal growth factor, insulin, glucagon., and ACTH 1‐17. Attention is called to the potential importance of these rhythms to basic research and medicine. Other circadian rhythms in the alimentary tract are reviewed briefly, such as those characterizing a host of intestinal enzymes, monosaccharide transport, and the height and width of the villi. Many of these have been shown to be cued to a feeding schedule; however, a number of the enzyme rhythms persist for one or two cycles in fasting animals, and this also is the case for the cell‐proliferation rhythms.After having been acclimated to a circadian feeding schedule (within a range of 23–30 hr), rodents can on subsequent days anticipate the food an hour or more prior to its arrival. Some enzymes behave in a similar manner in that their activities increase prior to the expected intake of the daily food. These anticipatory response rhythms are under endogenous control, since both will persist in the fasted animal and both will free run when a mouse is placed under constant conditions. Somehow these animals are able to measure circadian intervals of time. This challenges the concept that the oscillations seen in enzyme activities are simply a passive consequence of feeding and fasting, respectively.
The clinical application of chronobiology to oncology
Authors: Hrushesky William J. M. 
Published: February 2005

AbstractThe introduction to medical practice of chemical agents for fighting human cancer some 30 years ago brought hope to a field of medicine previously shrouded in despair and impeded by superstition. Gradually more and better agents have become available to the physician and to the patient suffering from cancer. The physician‐scientist has, in turn, learned a great deal about normal and abnormal cellular biology by using these drugs as probes. The observations that certain tissues and certain tumors share patterns of drug toxicity have led to a broadening of biologic understanding and to the use of combinations of drugs with shared antitumor activity and unshared toxicities. This empiric art of cancer chemotherapy has resulted in great progress in the treatment of a large number of advanced cancers. As important, however, is that this experience has resulted in knowledge which is leading to the development of rationally designed therapeutic regimens; to drug analogues seeking greater therapeutic‐toxic ratios; to the development of methods for chemically interfering with toxic drug effects while allowing or enhancing antitumor effect; and to work defining effects of drug timing. Drug timing research considers drug dosage in respect to the timing of a drug relative to the timing of other drugs (drug‐time‐drug interactions) or to other doses of that same drug (drug‐drug interval); the order of drugs (drug‐drug sequence); and the timing of drugs relative to an internal organismic time structure (time‐drug interactions). Data in this brief review clearly show that drug timing needs to be considered when designing rational chemotherapy for a living organism suffering from a cancer. The beautiful spatiotemporal complexity of life is not to be ignored or avoided, but should be considered as a golden opportunity to use what few imprecise chemical weapons we have a little more effectively.
Leydig cell development in the pig testis during the late fetal and early postnatal period: An electron microscopic study with attention to the influence of fetal decapitation
Authors: Van Vorstenbosch C. J. A. H. V. , Colenbrander B. , Wensing C. J. G. 
Published: February 2005

AbstractThe ultrastructure of fetal and postnatal pig Leydig cells was studied from 75 days postcoitum (p.c.) to 1 month after birth. Additionally, decapitated fetuses from 75 days p.c. until birth were used to study the effect of deprivation of gonadotrophins on the ultrastructure of Leydig cells.Normal Leydig cell development was characterized by a change in smooth endoplasmic reticulum (SER). Next to branched tubular SER, whirls of elaborate and tightly packed SER membranes appeared. The amount of SER increased with age but decreased slightly before the end of the observation period. Rough endoplasmic reticulum (RER) was a minor component. Large bundles or whirls of intermediate filaments were abundant until just before birth; thereafter, they decreased drastically. Peroxisome‐like structures and crystalloid bodies were observed with increasing frequency from 75 days p.c. and 20 days postpartum onward. Polygonal lysosome‐like dense bodies transformed into complex membranous structures especially after birth. Giant mitochondria occurred in the late fetal and postnatal period.From 75 days p.c. onward fully developed Leydig cells were scarce in testes of decapitated fetuses. Leydig cell characteristics disappeared toward the end of the fetal period; only the cell shape, the large bundles or whirls of intermediate filaments, some scarce polygonal lysosome‐like dense bodies, and RER remained, but SER was negligible. Progressive hemorrhages apparent in situ were correlated positively with fetal age. The dependency of Leydig cells upon LH began between 60 and 75 days postcoitum.
Microdissection by ultrasonication: Scanning electron microscopy of the epithelial basal lamina of the alimentary canal in the rat
Authors: Low Frank N. , McClugage Samuel G. 
Published: February 2005

AbstractThe epithelial basal lamina of the various parts of the alimentary canal of the rat was exposed by removal of the overlying epithelium. This was achieved by prolonged fixation in OsO4 or immersion in aqueous boric acid or both, followed by dehydration in acetone and exposure to ultrasonic vibration.The surface of the esophageal basal lamina is undulating with smooth hills and valleys, the smallest of which model the basal surfaces of the germinal cells of the epithelium. The stomach presents a perforated appearance because of ostia formed by evaginations of the basal lamina to enclose glands. In the small intestine, clavate rather than cylindrical villous cores are separated by ostia of intestinal crypts. In the large intestine, ostia are separated by broad areas of basal lamina in the cecum but are close together in the colon. The complex contours of the basal lamina are largely determined by the basal surface of the overlying epithelium but may be affected by structures in the underlying interstitium. Subepithelial lymph nodes, for example, are covered by a conspicuously porous basal lamina. Each nodule may be surrounded by ostia of as many as 20 crypts of Lieberkühn. The basal lamina of the ileocecal valve displays gradual transition from ileum to cecum.
Quantitative determination of the intracellular fate of internalized plasma membrane in dissociated pituitary prolactin cells utilizing a radioiodinated cationic ferritin probe (CFI*) and electron microscopic autoradiography
Authors: Rosenzweig Lionel J. , Kanwar Yashpal S. 
Published: February 2005

AbstractDissociated anterior pituitary cells derived from estrogen‐treated female rats were incubated with radioiodinated cationic ferritin (CFI*) for 2 min and subsequently in the absence of CFI* for varying periods of time up to 3 hr in order to quantitate, using electron microscopic autoradiography, the distribution of retrieved plasma membrane in these cells. Following a 2‐min incubation with CFI*, autoradiographic grains were found to be associated almost exclusively with the plasma membrane. With increasing periods of incubation in the absence of CFI*, grain‐density analysis revealed increasing levels of CFI* in multiple intracellular organelles. The levels of CFI* were greatest for the lysosomes, intermediate for the mature secretory granules, and least for the Golgi cisternae and immature secretory granules. These findings are consistent with the idea that a portion of the retrieved plasma membrane is degraded in lysosomes and that the remainder is recycled to organelles comprising the secretory pathway to be reutilized in successive waves of the secretory cycle.
The morphology and hormonal responsiveness of developing skeletal elements in chick limb buds
Authors: Ballard Timothy A. , Biddulph David M. 
Published: February 2005

AbstractWhile parathyroid hormone (PTH), calcitonin (CT), and certain prostaglandins (PGs) are known to regulate the metabolism of both osteogenic and osteolytic cells of the adult skeleton through an adenosine 3′,5′‐monophosphate‐dependent mechanism, little is known about the development of this hormonally mediated response in embryonic skeletal tissues. In the present study, the responsiveness of embryonic skeletal elements to PTH and PGE2 was examined during various stages of development utilizing cAMP concentrations as an indicator of hormone‐receptor interaction. The cytology of the limb skeletal system was examined also at each stage tested in order to compare the differentiated cellular phenotypes with their hormonal responsiveness. Prior to differentiation of cartilaginous elements in developing limb buds (stage 20–21), cells were responsive to PGE2 and epinephrine (EPI) but not to PTH. The first consistent response to PTH occurred coincident with the initial differentiation of the cartilage phenotype in limb buds (stage 24–25). A responsiveness to both PTH and PGE2 was progressively increased as maturation of cartilaginous and osteogenic elements occurred (stage 26–35). The initial response to CT was detected within cartilage rods in which osteogenic cells had differentiated (stage 33–35). The results of this study indicate that PGE2‐sensitive cells exist within the developing limb prior to cytodifferentiation. The development of PTH responsiveness within embryonic chick limb buds is correlated with the onset of both chondrogenesis and osteogenesis in vivo.
The early development of the hypoglossal nerve and occipital somites in staged human embryos
Authors: O'Rahilly Ronan , Müller Fabiola 
Published: February 2005

AbstractSerial sections of 105 human embryos (including 20 silver preparations) from stage 11 (24 days) to stage 22 (54 days) were studied, and 23 graphic reconstructions were prepared. The hypoglossal nucleus is evident at stage 12 and becomes isolated from other efferent nuclei at stage 14. The first hypoglossal nerve fibers appear at stage 12. The roots unite at stage 14 and the main trunk arrives in the tongue at stage 15. Four occipital somites can be identified during stage 13, and the sclerotomic material forms two bilateral masses. The fourth sclerotome separates in stage 14 and develops like a vertebra. This and the remaining sclerotomic material form the basioccipital and exoccipital parts of the chondrocranium, which are the first to appear. Four occipital myotomes develop and grow towards the tongue as the “hypoglossal cord”, which arrives prior to the hypoglossal nerve. The developmental similarity in the hypoglossal region between birds and mammals, combined with experimental studies in birds, renders it extremely likely that the hypoglossal musculature in mammals also is derived from occipital somites. The present study is the first in which this conclusion is adequately supported in the human. This investigation aids in the interpretation and timing of origin of variations (e.g., bipartite hypoglossal canal) and anomalies (e.g., persistent hypoglossal artery).
Microvascular architecture of the pampiniform plexus‐testicular artery system in the rat: A scanning electron microscope study of corrosion casts
Authors: Ohtsuka Aiji 
Published: February 2005

AbstractThe vascular architecture of the rat pampiniform plexus was studied by scanning electron microscopy of vascular corrosion casts. The plexus consists of a thick bundle of many anastomosing veins that entirely and closely surround the convoluted segments of the testicular artery. This specially developed close contact of the pampiniform plexus with the testicular artery may allow heat exchange between the plexus and the artery to maintain the cooled condition of the testis. The epididymal arteries are also closely surrounded by the networks of the epididymal veins. It is likely that heat exchange may operate even between these epididymal vessels. The ductus deferens is provided with no vascular channels for such heat exchange. A loose or coarse capillary network is always observed between the testicular artery and the pampiniform plexus. This network is supplied by the epididymal arteries and drains into the pampiniform plexus.
Dimensional analysis and dynamic response characterization of mammalian peripheral vestibular structures
Authors: Ramprashad Fred , Landolt Jack P. , Money Kenneth E. , Laufer Jerry 
Published: February 2005

AbstractExtensive morphometric measurements were made on the vestibular system of the rabbit (Oryctulagus cuniculus), the gerbil (Meriones unguiculatus), the chinchilla (Chinchilla laniger), and the squirrel monkey (Saimiri sciureus) from serial sections of temporal bones. Additionally, a more limited set of measurements were also completed on the owl monkey (Aotus trivirgatus), the Capuchin monkey (Cebus sp.), the harp seal (Pagophilus groenlandicus Erxleben, 1777), and the two‐toed sloth (Choloepus sp.). The following measurements were made: (1) radius of curvature (R) of each membranous semicircular canal (herein called semicircular duct—see nomenclature in Nomina Anatomica (1968)) (2) cross‐sectional diameter of the ducts and the osseous semicircular canals, and (3) some pertinent morphometrics of the cristae ampullares and the utricle. In all species studied (1) the radii of curvature of the three semicircular ducts are dissimilar, with that of the lateral duct being as small as, or smaller than, those of the anterior and posterior ducts; (2) R for the anterior duct is largest in the harp seal and the rabbit; (3) the canal and duct dimensions are largest in the Capuchin and squirrel monkeys, the two‐toed sloth, and the harp seal, and smallest in the gerbil; (4) the proportion of otic fluid “space” that is occupied by endolymph shows a ranking of gerbil > rabbit > two‐toed sloth > chinchilla = owl monkey > squirrel monkey > Capuchin monkey > harp seal; and (5) the gross ampullary and utricular dimensions are largest in the harp seal and smallest in the gerbil. These measurements were used for determining the time constants describing semicircular‐canal dynamics in the Steinhausen (1931, 1933) and Oman‐Marcus (1980) equations.
Enzyme histochemical differentiation of white adipose tissue in the rat
Authors: Hausman G. J. , Thomas G. B. 
Published: February 2005

AbstractSubcutaneous adipose tissues from fetal and young rats were studied with enzyme histochemical techniques. Lipid staining and histological evaluation were also utilized to compare the development of a wide variety of enzyme activities to cytoplasmic lipid deposition and morphological differentiation of adipocytes. Three distinct stages of adipose‐tissue differentiation were postulated. In stage III, adipocytes were morphologically differentiated (rounded, basal‐lamina positive) and enzyme reactive for many enzymes. In stage II, however, adipocytes were reactive for some enzymes but were not morphologically differentiated. Stage I adipose tissue was histologically distinct from connective tissue but did not contain lipid‐laden cells or enzyme‐reactive cells. Stages I and II (95%) were predominant in fetuses, whereas stage III (90%) was predominant in young animals. Histochemical analysis of adipocytes in newborn rats established the metabolic competence of these cells despite their small size. These studies indicate that enzymatic differentiation of adipocytesclearly precedes morphological differentiation.
Arterial anatomy of chicken embryo and hatchling
Authors: Levinsohn E. Mark , Packard David S. , West Elizabeth M. , Hootnick David R. 
Published: February 2005

AbstractThe arterial pattern in chicken hatchlings was investigated by microangiography and microscopic analysis of cleared specimens. The hatchling arterial pattern was found to resemble strongly the pattern that has been described for the adult chicken. Several minor variations in this pattern were found which were probably due to species, strain, or age differences. We also investigated the arterial pattern in chicken embryos aged 4.5 to 21 days of incubation. The hatchling pattern was fully developed by approximately 8 days of incubation. Some similarities were found to exist between the embryonic pattern in the chicken embryo and that described for the human embryo.
Surface topography and distribution of cell types in the rat nasal respiratory epithelium: Scanning electron microscopic observations
Authors: Popp James A. , Martin Joseph T. 
Published: February 2005

AbstractSeveral cell types were identified in the rat nasal respiratory epithelium using scanning electron microscopy. In addition to the previously described ciliated, nonciliated, and goblet cells, the nasal brush cell was identified based on its surface characteristics and its location between nonciliated epithelial cells. Scanning electron microscopy clearly showed the differences in distribution of cell types in the nasal mucosa. The ciliated cells increase in number from the anterior to the posterior areas of the respiratory epithelium with a corresponding decrease in nonciliated cells. However, even at a single cross‐sectional area of the nasal cavity, the various surfaces have different proportions of ciliated versus nonciliated cells, e.g., the medial surface of the nasal concha has more ciliated cells than other surfaces. Brush cells are distributed between nonciliated cells of the respiratory epithelium on most surfaces of the nasal cavity including the conchae and the lateral wall. Based on the available information, scanning electron microscopy will be useful in future studies to determine the effects that inhaled toxicants have on cells and on the location of lesions.