bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of fluorodeoxyuridine, colcemid, and bromodeoxyuridine on developing neocortex of the mouse
Authors: Webster William , Shimada Morimi , Langman Jan 
Published: February 2005

AbstractThe purpose of this study was to obtain information about factors controlling the interkinetic movement of neuroepithelial cells and the cortical migration of neuroblasts in the developing mouse neocortex. In the first experiment 15‐day pregnant mice were injected with a single dose of fluorodeoxyuridine, a compound which inhibits the enzyme thymidylate synthetase thus blocking DNA‐replication. The animals were sacrificed at various hours and days following treatment. Two hours after treatment the mitotic index of the neuroepithelial cells was severely reduced and cells with abnormal nuclei appeared in the DNA‐synthesizing zone of the neuroepithelial layer. By five hours more abnormal cells appeared and many showed degenerating nuclei. By 12 hours cells with abnormal nuclei were seen in the outer half of the neuroepithelial layer and some in the migratory zone. Since they were not seen at the lumen, these observations indicate that fluorodeoxyuridine‐affected nuclei do not move to the lumen and do not divide. By 24 hours abnormal nuclei were seen in the migratory zone and cortical plate suggesting cortical migration without preceding cell division. In the second experiment 15‐day pregnant mice were treated with col‐cemid, a compound which arrests dividing cells in metaphase. Two and four hours after injection a large number of neuroepithelial cells in metaphase accumulated at the lumen. By seven and 12 hours the number of arrested metaphases decreased rapidly, but at the same time cells with dense, darkly stained nuclei appeared in the adjacent neuroepithelium. By 24 hours these abnormal nuclei were present in the migratory zone and cortical plate, suggesting that they were migrating towards the surface of the cortex despite the failure to complete mitosis. In the third experiment 15‐day pregnant mice were injected with bromodeoxyuridine, a compound incorporated into DNA and thought to interfere with differentiation. During the first 12 hours after treatment a striking increase in the number of normal mitotic figures was seen at the lumen. By 16 hours, however, abnormal mitotic figures started to appear. Since the generation time of neuroepithelial cells at this stage of development is about 13 hours, the abnormal mitotic figures must represent cells which have gone through two DNA‐synthetic periods since the beginning of the treatment. The abnormal mitotic figures give rise to cells with dense pycnotic nuclei which by 24 hours are found throughout the width of the developing neocortex. Thus in each experiment cells with abnormal, presumably non‐functional, nuclei were produced. Despite the failure to divide or to carry out a normal division, the nuclei migrate from the neuroepithelial layer towards the cortical plate in a fashion similar to that of normal postmitotic neuroblasts.
The ontogeny of cell‐mediated immunity: The response of the mouse to dinitrofluorobenzene (DNFB)
Authors: Schneider Gary B. 
Published: February 2005

AbstractCellular immunocompetence begins to develop in mice during the first week after birth, as indicated by skin allografting and graft‐versus‐host reactions, but delayed hypersensitivity has not yet been detected at this early age. The purpose of this study was to investigate the ontogeny of delayed hypersensitivity in suckling mice.Dinitrofluorobenzene (DNFB) is an antigenic hapten which, when applied to the skin, can elicit both delayed hypersensitivity and a humoral immune response. In adult mice the induction period of delayed hypersensitivity to DNFB is a blastogenic reaction (accumulation of lymphoblasts) in the diffuse, thymusdependent cortex of the lymph node draining the site of application. This blastogenic reaction reaches a peak three days after initial application of antigen and then subsides, to be followed by the development of germinal centers and numberous plasma cells — indicative of a humoral immune response — a week after initial sensitization.Suckling mice were sensitized by application of DNFB to the ears, and the auricular lymph nodes wer prepared for light and electron microscopy three and eight days after sensitization. The development of delayed hypersensitivity was assayed by applying DNFB to an ear, 5 to 12 days after initial sensitization, and measuring the increase in thickness of the ear 24 hours later.The results of these studies indicate that by two days of age, mice have the capacity to develop delayed hypersensitivity as shown by both a blastogenic reaction in the draining lymph node and a positive skin test. Mice sensitized at birth or on the next day did not respond in either way. Mice sensitized prior to two weeks of age did not develop the late phase of the response (the formation of germinal centers and plasma cells), which matured in parallel with the normal maturation of the machinery for antibody production during the third postnatal week.These observations strengthen the conclusion of previous investigations that the blastogenic response in the regional lymph node is the inductive phase of delayed hypersensitivity. Because the late phase of the response does not appear in mice sensitized before two weeks of age, these animals offer an unusual opportunity to study delayed hypersensitivity relatively uncomplicated by humoral antibody production.
Human retinal development: Ultrastructure of the outer retina
Authors: Hollenberg Martin J. , Spira Arthur W. 
Published: February 2005

AbstractThe morphogenesis of the outer human retina from 6.5 to 18 weeks of gestational age (16–156 mm) was studied by light and electron microscopy. During this period the retinal pigment epithelium changes from a pseudostratified columnar epithelium, with mitoses at its inner edge, to a single layer of cuboidal cells. Initially, mature pigment granules, premelanosomes, polysomes, rough endoplasmic reticulum and a Golgi complex occupy the epithelial cytoplasm. Lateral epithelial surfaces show infoldings and neighboring epithelial cells are bound at their inner borders by a junctional complex consisting of a zonula occludens and zonula adherens. Later, pigment epithelial development is marked by an increase in cytoplasmic organelle content and the appearance of slender processes at the inner epithelial border. Initially, the outer neural retina is formed by a uniform population of elongated cells containing oval nuclei with multiple nucleoli and, in the cytoplasm, mitochondria, polysomes and the Golgi complex. Cell division is common in the proliferative layer at the outer edge of the posterior neural retina until 120 mm crown‐rump length, and cell membrane junctions between outer neuroblasts remain intact during mitosis. Cilia project outwards from outer neuroblasts and invaginate the immediately adjacent pigment epithelium. At 120 mm crown‐rump length, differentiating rods, cones and Müller cell processes are distinguishable and developing ribbon synapses and surface contacts are present at the base of the cone prior to outer segment formation.
Autoradiographical and morphological evidence for apocrine secretion of dipalmitoyl lecithin in the terminal bronchiole of mouse lung
Authors: Etherton John E. , M. Conning David , Corrin Bryan 
Published: February 2005

AbstractThe Clara cell of the mouse terminal bronchiole has been examined by high resolution phase contrast and electron microscopy, and the secretory route of surfactant in the mouse lung has been investigated using both light and electron microscopical autoradiography of a surfactant precursor (palmitic acid). Serial sections of terminal bronchioles examined by phase contrast microscopy demonstrated the appearances of apocrine secretion of amorphous droplets by Clara cells. Electron microscopy showed that the non‐decapitating supranclear region of Clara cells contained numerous rounded mitochondria with scanty achrestic cristae, whilst the apical portion was rich in smooth tubular membranes. Autoradiographical labeling of bronchiolar Clara cells exceeded that of all other cell types within three minutes of administration of the radioactive precursor, with location primarily over the endoplasmic reticulum. Subsequently there was heavy labeling of the bronchiolar lining layer. An hour later, silver grains were most numerous over the lamellated bodies of type II cells. It is suggested that palmitic acid is synthesized in the specialized mitochondria of the non‐secretory region of the Clara cell and is incorporated into dipalmitoyl lecithin in the membranous apex. Subsequent secretion, possibly by the apocrine mechanism, provides a surface‐active bronchiolar lining layer.
Pathogenesis of osteopetrosis in the ia rat: Reduced bone resorption due to reduced osteoclast function
Authors: Marks Sandy C. 
Published: February 2005

AbstractOsteopetrosis, a skeletal condition characterized by excessive accumulation of bone, is an inherited disease in man, rats and mice. In ia rats the condition undergoes spontaneous permanent remission beginning 30 to 50 days after birth, in contrast to the disease in mice and men. Thus, the ia rat offers a unique opportunity to analyze factors suspected of causing the skeletal condition.In the present investigation bone formation and bone resorption have been measured at various ages in ia rats and normal littermates. Bone matrix formation, measured by 3H‐proline uptake, was decreased slightly during the first three postnatal weeks and elevated slightly thereafter. Bone resorption, stimulated by injection of parathyroid extract, was determined in vivo as the rate of release of 3H from bone after incorporation of 3H‐proline. Bone resorption was reduced 20% at two weeks and elevated 20% by three weeks. Administration of parathyroid extract or thyroxine, or a deficiency of thyrocalcitonin produced by thyroidectomy (supplemented with thyroxine), did not hasten remission. An abnormally high cytoplasmic concentration of acid phosphatase activity was observed in ia osteoclasts during the first two weeks. The skeletal signs of spontaneous remission, appearing between 30 and 50 days after birth, were preceded by a normal response of the serum calcium to exogenous parathyroid extract, by increased bone resorption and by a more normal cytoplasmic distribution of acid phosphatase activity during the third postnatal week.These observations are interpreted to indicate that the osteopetrotic condition of ia rats is not due to deficiencies of parathyroid hormone or thyroxine or an excess of thyrocalcitonin but results from failure of osteoclasts to respond to stimuli promoting resorption. Specifically, these cells seem able to synthesize but not release normal amounts of the lysosomal enzyme acid phosphatase.
Effects of mammalian corticotrophin on the ultrastructure of presumptive interrenal cells in the opisthonephros of the lamprey, Petromyzon marinus L.
Authors: Youson John H. 
Published: February 2005

AbstractThe administration of mammalian corticotrophin to larvae and adult sea lamprey, Petromyzon marinus L., results in changes in fine structure of cells within presumptive interrenal tissue located in the opisthonephric kidneys. Compared to controls, stimulated cells show increases in the volume of smooth endoplasmic reticulum, mitochondria, and the Golgi apparatus with an accompanying decrease in numbers of lipid droplets. In addition, the plasma membrane near a perivascular space is commonly highly folded. Mitochondria are often of unusual configuration and possess “puffs” and the cristae are more tubular than in controls. The enlarged Golgi apparatus is accompanied by large numbers of coated vesicles.The morphological features of corticotrophin‐stimulated presumptive interrenal cells of lampreys closely resemble the appearance of adrenocortical cells of mammals and the interrenal cells of other vertebrates after similar stimulation. These results suggest that these cells in lampreys and adrenocortical cells are likely homologs.
The atrioventricular valves of the guinea‐pig. I. A light microscopic study
Authors: Ellison Jeffrey P. , Hibbs Richard G. 
Published: February 2005

AbstractThe atrioventricular valves contain dense plexuses of adrenergic nerve fibers, derived from atrial and ventricular sources. Most of the adrenergic terminals are located in the lower third of the cusps. This region, which contains adrenergic terminals and acetylcholinesterase‐positive nerve endings is devoid of muscle fibers and blood vessels. The acetylcholinesterase‐positive endings may be sensory; and norepinephrine released from the adrenergic terminals may influence their performance. In the mitral valve, the atrial adrenergic plexus is separated from the ventricular plexus by a narrow zone that is free of adrenergic nerves. In most other respects the innervation, musculature and vascular supply of the mitral valve is similar to that of the tricuspid valve.Each valve has an intrinsic skeleton. This is made up of collagenous “ribs” that pass up from the chordae tendineae and fan out in the cusps. “Ribs” from adjacent chordae overlap and interweave, forming a complex support system.The musculature of the valves is complex and seems to have several functions. The annular muscle around the valve orifice may act as an atrioventricular sphincter, while offshoots that insert into the collagenous “ribs” of the cusp may assist the papillary muscles in maintaining tension on the cusps. The meshwork of muscle fibers between “ribs” may prevent ballooning of the cusps during systole. We found no consistent association between valvar muscles and nerves. Blood vessels are restricted mainly to the upper muscular part of the cusps, although a few capillary loops descend into the midzone of the cusps.
Electron microscopic studies of human pituitary tumors. I. chromophobic adenomas
Authors: Schechter Joel 
Published: February 2005

AbstractTen cases of chromophobic adenoma have been studied by electron microscopy; seven were associated with hypopituitarism and three with acromegaly. Comparison of the tumors revealed that morphological variations in parenchymal cell types were slight, and, based on characteristics of the secretory granules, a single cell type was predominant and common to both varieties of the tumor. The predominant cell type contained varying amounts of secretory granules that measured 80–200 mμ or more in diameter, and had an electronopaque core and perigranular halo. Though the features of these secretory granules were most like those in “normal” adult basophils this classification is considered doubtful. The core material of the secretory granules was homogeneously electron‐opaque in some granules and particulate in others. In addition to electron‐opaque core material many secretory granules contained aggregates of clear vesicles. Some granules did not contain clear vesicles but were closely associated with numerous cytoplasmic vesicles. Lysosomes were abundant and a consistent feature of the tumor cells. The present observations indicate that cell features are significantly altered in the cells of both varieties of chromophobic adenoma so that ultrastructural criteria used to identify cell types in “normal” pituitary glands are not applicable to the tumor cells.Chromophobic adenomas associated with acromegaly varied more with respect to the features of the predominant cell type than did chromophobic adenomas associated with hypopituitarism. Cell features varied between cells with electronlucent cytoplasmic matrix and scant development of organelles to others with more electron‐opaque cytoplasmic matrix and more complex development of organelles. Common to both varieties of tumor were marked variations in the number and structure of mitochondria from cell to cell; occasionally mitochondria filled the cytoplasm.
Three‐dimensional structure of the osmium‐impregnated golgi apparatus as seen in the high voltage electron microscope
Authors: Rambourg A. , Clermont Y. , Marraud A. 
Published: February 2005

AbstractOsmication in an unbuffered aqueous solution of osmium tetroxide allows the forming face of the Golgi apparatus to be labeled in many cell types. This property was utilized to study the spatial configuration of this organelle by examining stereopairs of the same field taken at 1,000 KV after tilting a thick (1 to 7 μUm) section of − 7° or + 7° from the original (0°) position. When examined in 1 μm thick sections at magnifications ranging from 13,000 to 18,000 times, the osmic acid‐impregnated element of the Golgi apparatus of ganglion nerve cells, Leydig cells or Sertoli cells takes the appearance of a single layered polygonal network of tubules. This network can only be seen at electron microscope magnifications and is referred to as the primary network or structure of the forming face of the Golgi apparatus. When 2 to 7 μm thick sections are examined under progressively lower magnifications, the details of the primary structure remain discernible but become less conspicuous. The osmiophilic portion of the Golgi apparatus now extends over large areas of the cytoplasm to form an extensive continuous structure. This structure which is in the range of visibility of the light microscope is referred to as the secondary network or structure of the forming face. In ganglion nerve cells, the secondary structure consists of a perinuclear network showing slender projections reaching the nucleus and wider expansions approaching the cell surface; in the Leydig cells it appears as an ovoid structure located at one pole of the nucleus whereas in Sertoli cells it forms a cylindrical structure located in the main shaft of the cytoplasm and extending from the nucleus towards the lumen of the seminiferous tubule. Thus the forming face of the Golgi apparatus displays a primary structure; the tubular roughly polygonal network, which is similar in the three cell types and a secondary structure which varies from cell to cell.
The role of the convoluted segment of the proximal tubule in the disposal of 131I‐insulin in the rat kidney
Authors: Sottiurai Vikrom 
Published: February 2005

AbstractIt is generally accepted that in the kidney insulin is metabolized in the proximal tubule, but whether in the convoluted segment, the straight segment, or both has not been established. By means of autoradiography counting of radioactivity, and interrupted flow techniques, the following observations have been made. 131I‐labelled porcine insulin is metabolized exclusively in the convoluted segment of the proximal tubule. Although the glomerular filtrate is the major source of insulin supply to the renal epithelia, the peritubular capillary plexuses provide as much as 30% or more of the total insulin delivered to the renal epithelia. The epithelium of the convoluted segment is capable of sequestering 131I‐insulin from the peritubular capillary plexuses, a phenomenon which has not been established previously.
Bronchiolar neuro‐epithelial bodies in the neonatal mouse lungs
Authors: Hung Kuen‐Shan , Loosli Clayton G. 
Published: February 2005

AbstractBronchiolar neuro‐epithelial bodies in neonatal mice were studied by light and electron microscopy. These bodies occurred in thickened areas of the epithelium, and consisted of groups of specialized, non‐ciliated columnar epithelial cells with many cytoplasmic granules. These cells were usually closely parallel to one another and had elongated nuclei containing conspicuous peripheral chromatin condensations. These cells were associated with intra‐epithelial axons.With electron microscopy, the non‐myelinated axon under the neuro‐epithelial body was observed to penetrate the basal lamina and enter the epithelial layer. After penetration, the intra‐epithelial axon containing numerous mitochondria lost its Schwann cell sheath, became enlarged, and ramified among the epithelial cells.These innervated neuro‐epithelial bodies probably function as sensory receptors in the bronchioles.
A cytoplasmic inclusion in mouse trigeminal neurons
Authors: Peach Roy , Koch William E. 
Published: February 2005

AbstractMouse trigeminal neurons contained a cytoplasmic inclusion consisting of a dense particle (diameter ∼ 100 nm.) surrounded by a smooth surfaced membrane sometimes in continuity with the rough surfaced endoplasmic reticulum. The identity of the inclusion is uncertain but it may be related to intracisternal A type particles.
Altered fine structure of B lymphocytes correlated with defective terminal differentiation
Authors: Bockman Dale E. , Wu L. Y. Frank , Lawton Alexander R. , Cooper Max D. 
Published: February 2005

AbstractPeripheral blood lymphocytes from three patients with defective differentiation of B cells were studied by routine electron microscopic techniques. One patient had severe combined immunodeficiency with rudimentary development of the B cell line. Two had immune deficits secondary to the B cell malignancy, chronic lymphocytic leukemia. Accumulations of tuboreticular structures were found in the cytoplasm of lymphocytes from the severe combined immune deficiency patient, sometimes in close association with annulate lamellae. The tuboreticular structures resemble those described in lymphocytes and endothelial cells of patients with systemic lupus erythematosus. In one patient with chronic lymphocytic leukemia, cylindrical arrangements of ribosomal material occupied the cytoplasm of many lymphocytes. These cylinders were observed in samples of blood drawn at different times and after tissue culture of lymphocytes with and without pokeweed mitogen. The other patient with chronic lymphocytic leukemia had circulating lymphocytes with material identified as IgM in the perinuclear spaces and dilated cisternae of the rough endoplasmic reticulum. This material sometimes had a crystalline structure.These observations indicate that in some cases functional immunological deficits in B cells, manifested by failure to differentiate to mature secretory cells, may be correlated with morphological aberrations of protein‐manufacturing organelles within the cell.
Secretory processes in follicular cells of the bat thyroid. III. The occurrence of extracellular vesicles and colloid droplets during arousal from hibernation
Authors: Nunez Eladio A. , Wallis Jeffrey , Gershon Michael D. 
Published: February 2005

AbstractUltrastructural changes that occur in follicular cells of the bat thyroid gland just prior to, and immediately after arousal from hibernation are discussed in relation to the known changes which occur in thyroid function during arousal from hibernation. The most distinctive ultrastructural change that takes place just before emergence from hibernation is the occurrence, extracellularly, of concentrations of small vesicles lying in the colloid near the cell's apical plasma membrane. Similar accumulations of vesicles are absent in the apical cytoplasm of the follicular cell. Other principal changes from the early hibernating state found at this time are an increase in the number of apical vacuoles, dense granules and multivesicular bodies. These changes are followed at arousal itself by the appearance of large numbers of intracytoplasmic colloid droplets, often intimately associated with dense granules. An unusual feature of these follicular cells is that although they are rich in colloid droplets, apical pseudopods cannot be found.