bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sequence of developmental alterations following acute ethanol exposure in mice: Craniofacial features of the fetal alcohol syndrome
Authors: Sulik Kathleen K. , Johnston Malcolm C. 
Published: February 2005

AbstractThe typical facial features of the fetal alcohol syndrome (FAS) were induced in C57B1/6J mice with acute maternal ethanol administration at gastrulation stages of embryonic development. These features include microcephaly, microphthalmia, short palpebral fissures, deficiencies of the philtral region, and a long upper lip. Scanning electron microscopic (SEM) analysis of embryos 24 hours following initial ethanol exposure at 7 days 0 hours of gestation revealed an obvious size reduction in the neural plate, which was particularly noticeable in the forebrain region. As expected, deficiencies in neural plate development at these early stages result in abnormal brain and eye formation. SEM analysis of later embryonic stages revealed the development of closely set olfactory placodes with resultant deficiencies in the medial nasal prominences (that area responsible for forming the philtral region of the upper lip, the alveolar ridge containing the upper incisors, and the anterior portion of the hard palate—the primary palate). Cleared skeletal preparations of affected newborns had marked premaxillary bone deficiencies. One of the most prevalent known human teratogens has a major malformation‐inducing effect on gastrulating embryos, a developmental stage present in human embryos prior to pregnancy recognition by most women.
Ultrastructure of the placenta and fetal membranes of the dog: II. The yolk sac
Authors: Lee Sue Y. , Anderson John W. , Scott Grayson L. , Mossman Harland W. 
Published: February 2005

AbstractYolk sacs from dogs at 40, 50, and 60 days of gestation were examined by electron microscopy. Free ribosomes, mitochondria, and rough endoplasmic reticulum (rER) are more prominent in both endoderm and mesothelium at 40 and 50 days than at 60 days, suggesting a greater synthetic capacity at the earlier stages. Smooth endoplasmic reticulum (sER) and glycogen are also present in greater amounts in the endoderm in the earlier stages. In the mesothelium, however, low amounts of sER and glycogen are consistently present. Certain possibilities relative to the nature of the synthetic activities in these two tissues are discussed. Large amounts of smooth‐surfaced vesicles were observed along the basal edges of the 60‐day mesothelium; they are indicative of transport processes occurring at this time. As gestation proceeds, in both endoderm and mesothelium, the Golgi complex remains well developed, there are more numerous lysosomelike bodies, and bundles of intermediate filaments either increase or become more diffused. In some endoderm cells at 60 days, large vacuoles and dense glycogen deposits were noted. These observations indicate that degenerative processes are gradually occurring in the endoderm and mesothelium as parturition draws near. Erythropoiesis occurs in the mesenchyme at 40 and 50 days. At 40 days also, segments of endothelium were seen within blood islands, indicating that the endothelial lining of some yolk sac vessels differentiates from cells located in the interior of such islands.
Comparative ultrastructure of the inner capsule of the muscle spindle and the tendon organ
Authors: Ovalle William K. , Dow Pierre R. 
Published: February 2005

AbstractThe ultrastructure of inner capsule cells of the vertebrate muscle spindle was studied by transmission electron microscopy and compared with that of homologous cells in the tendon organ. Aside from variations in their complexity and pattern of organization, cells of the inner capsule in these two sensory receptors exhibited marked similarities in fine structure. The virtual absence of basal lamina in the region of the nucleated soma as well as on the branching cytoplasmic extensions of these cells was noted. In the inner capsule of both end organs, three kinds of intercellular specialization were encountered. Cell processes were typically linked together at multiple sites by intermediate junctions. In addition, focal points of membrane fusion between two or more cellular profiles were identified as tight junctions. In more extensive regions of plasma membrane overlap, gap junctions were also discerned. It seems probable that these sites along the inner capsule represent areas of mechanical and electrical linkage, enabling contiguous cells to function as a synchronous unit. Tight junctions may also provide the inner capsular sheath with specific permeability‐barrier characteristics. Elements of the Golgi complex and associated presecretory vesicles and cytoplasmic granules were prominent. Their presence implicates these cells in the elaboration of the paracellular connective‐tissue matrix occupying the intracapsular spaces of both receptors. The close resemblance of these cells to endoneurial fibroblasts of peripheral nerve and to hyalocytes of the vitreous body is emphasized. It is likely that, regardless of species examined, cells of the inner capsule in both receptors play an overall protective role in the formation, maintenance and regulation of their luminal paracellular contents.
Morphometric analyses on the muscles of exercise trained and untrained dogs
Authors: Čabrić M. , James N. T. 
Published: February 2005

AbstractNine adult dogs were subjected to an endurance training program consisting of gradually increasing periods of treadmill exercise. Biopsies of vastus lateralis muscles taken prior to and on completion of the training program were used to study the alterations in the capillary network and muscle‐fiber nuclei.Combined morphometric and stereological analyses showed that the total length of capillaries (LV) and their total surface area (SV) per unit volume of muscle was significantly increased during training.Changes in the properties of myonuclei following training were also studied. Highly significant increases in the number of nuclei per unit volume of muscle (NV) were found. The increase in the numerical density of muscle‐fiber nuclei would seem to indicate that the new nuclei were formed in the muscle during prolonged training. The relative amounts and distribution of heterochromatin and euchromatin were measured in trained and untrained dogs using a simple point‐counting and random‐transect technique. Their content of the different types of chromatin (volume functions and chromatin patch sizes in micrographs) were found to be altered significantly as a result of the training. The findings were consistent with the view that the amount of euchromatin within nuclei varies according to the degree of cellular activity.
The aging male rat: Structure and function of the kidney
Authors: Haley Diane P. , Bulger Ruth Ellen 
Published: February 2005

AbstractThe progression of anatomic and functional changes that occur with aging in normal male Sprague‐Dawley rats was investigated. Renal function studies were followed by vascular perfusion fixation of the kidneys. The kidneys were examined with light microscopy and scanning and transmission electron microscopy.The glomerular filtration rate of 12‐month‐old rats (0.30 ± 0.06 ml/min/100 gm body weight) was significantly lower (P < .05) than the rates of the 3‐month‐old (0.91 ± 0.08 ml/min/100 gm body weight) and 5‐month‐old (0.99 ± 0.16 ml/min/100 gm body weight) rats. Urine protein levels were moderately elevated in 12‐month‐old rats. Structural changes mainly involved the renal corpuscle and proximal tubule. The parietal layer of Bowman's capsule wa transformed from a squamous to a columnar epithelium resembling that of the proximal tubule in 48% of the capsules surveyed in 12‐month‐old rats. This value was significantly higher (P < .05) than that of the 5‐ (14%) or 3‐ (6%) month‐old rats. Thin sheets of cytoplasm extended from podocytic cell bodies over the layer of pedicels. The proximal tubule displayed focal areas of cell injury and necrosis. Basement membranes associated with the renal corpuscle, glomerulus, and proximal tubule were considerably thickened in the oldest group of rats. Some cellular infiltration occurred in the interstitium. Therefore, kidneys of aging Sprague‐Dawley rats exhibited capsular metaplasia, death, and injury of proximal tubular epithelial cells, and other structural changes not seen in younger animals. Some of these changes may underlie the functional deterioration of their kidneys.
Postnatal development of spiral ganglion cells in the rat
Authors: Schwartz Ann Marie , Parakkal Marianne , Gulley Robert L. 
Published: February 2005

AbstractThe postnatal development of the spiral ganglion in the albino rat was studied using light and electron microscopy. The morphological characteristics distinguishing type 1 from type 2 spiral ganglion cells were defined, and the critical period for distinguishing the two types of neurons was identified. At birth, the spiral ganglion consists of a homogeneous population of small, densely packed, spherical cells that have large cytoplasmic‐to‐nuclear ratios. During the first postnatal week, the cells mature slowly. At this period the myelin sheath around the cell bodies generally consists of only a few layers of loose myelin. Long glial fingers extend around the cell processes and soma, particularly the filopodial extensions of the somatic membrane. Type 2 spiral ganglion cells can be distinguished at postnatal day 8. Viewed with the phase‐contrast microscope these cells are smaller and have more darkly staining nuclei and more lightly staining cytoplasm than the type 1 cells. The most characteristic ultrastructural features of the type 2 neurons are the densely packed neurofilaments in the cytoplasm and lack of compact myelin around the cell soma. By day 14, spiral ganglion cells are morphologically mature, although the myelin sheath continues to thicken. The results are discussed in relation to the electrophysiological development of the auditory system and the morphological maturation of the organ of Corti.
Cell density and cell generation in the periodontal ligament of mice
Authors: McCulloch C. A. G. , Melcher A. H. 
Published: February 2005

AbstractThe number of cell nuclei per mm2 and the volume density of cell nuclei and blood vessels in the periodontal ligament at different levels of the mesial root of the first mandibular molar of the adult mouse and in different areas of the ligament at each level have been examined in the light microscope. Significantly higher numbers of cell nuclei per mm2 were observed adjacent to bone, cementum, and blood vessels than in the avascular body of the ligament at all levels and on all aspects of the root. This distribution of number of cell nuclei per mm2 was constant over 41/2 months of aging and a doubling of body weight. The volume density of cell nuclei was significantly higher in cells adjacent to bone and cementum and in gingival connective tissue than in both the vicinity of blood vessels and the body of the ligament. The blood vessels, which were present predominantly in the bone‐related half of the ligament, were absent from the zone immediately adjacent to cementum.The labeling indexes of periodontal ligament cells were determined from autoradiographs of the mesial root of the first mandibular molar of the mouse after pulse‐labeling with 3H‐Tdr. Labeling indexes were highest in zones adjacent to blood vessels, and the labeling index was significantly higher in the middle of the ligament than in zones adjacent to bone and cementum, and consequently was inversely related to cell density.
Ultrastructure of cartilage from young adult sea lamprey, Petromyzon marinus L: A new type of vertebrate cartilage
Authors: Wright Glenda M. , Youson John H. 
Published: February 2005

AbstractUltrastructural observations of cartilage from adult sea lamprey, Petromyzon marinus, reveal a highly cellular cartilage with an unusual extracellular matrix. The avascular cartilage is surrounded by a vascular perichondrium, which consists of dense connective tissue containing fibroblasts, collagen fibrils, and microfibrils. The cells (chondrocytes) vary in morphology in different parts of the cartilage in a way that may reflect their state of activity. Chondrocytes within the peripheral cartilage contain tubulo‐vesicular structures along the cell surface, an extensive lamellar rough endoplasmic reticulum, and a well‐developed Golgi complex with associated vesicles and vacuoles. The presence of material within the Golgi elements that resembles components of the extracellular matrix suggests the involvement of the peripheral chondrocytes in the synthesis and secretion of the matrix components. Chondrocytes within the central cartilage are hypertrophied and contain a pale cytoplasm with a reduced number of organells that are widely spaced throughout the cell. The appearance of the organelles within these cells suggests that they are not as actively involved in the production of the matrix as those of the peripheral cartilage. The extracellular matrix consists of a dense network of randomly arranged, branched, noncollagenous matrix fibrils 15–40 nm in diameter and varying amounts of electron‐dense matrix granules. Due to the unique nature of its extracellular matrix, the cartilage of the lamprey cannot be likened to any of the known vertebrate cartilages and, therefore, must be considered a new type of vertebrate cartilage.
Light microscopic immunolocalization of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin in the basement membranes of a variety of rat organs
Authors: Laurie G. W. , Leblond C. P. , Martin G. R. 
Published: February 2005

AbstractImmunohistochemical methods were used to determine whether type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan were present in diverse basement membranes. Antisera or antibodies against each substance were prepared, tested by enzyme‐linked immunosorbent assay, and exposed to frozen sections of duodenum, trachea, kidney, spinal cord, cerebrum, and incisor tooth from rats aged 20 days to 34 months. Bound antibodies were then localized by indirect or direct peroxidase methods for examination in the light microscope.Immunostaiing for type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan was observed in all of the basement membranes encountered. Fibronectin was also found in connective tissue. In general, the intensity of immunostaining was strong for type IV collagen and laminin, moderate for heparan sulfate proteoglycan, and weak for fibronectin. The pattern was similar in the age groups under study. Very recently the sulfated glycoprotein, entactin, was also detected in the basement membranes of the listed tissues in 20‐day‐old rats.It is accordingly proposed that, at least in the organs examined, type IV collagen, laminin, fibronectin, heparan sulfate proteoglycan, and entactin are present together in basement membranes.
Non‐lymphoid cells of the anuran spleen: An ultrastructural study in the natterjack, Bufo calamita
Authors: Barrutia M. S. García , Leceta J. , Fonfría J. , Garrido E. , Zapata A. 
Published: February 2005

AbstractThe present study is concerned with the ultrastructure of the spleen in the natterjack, Bufo calamita (Anura, Bufonidae), with special emphasis on the structure and function of the non‐lymphoid elements occurring in the red and white pulp. The organ consists of two clearly distinguishable areas, the white and the red pulp, separated by a prominent marginal zone. Thus, the pattern of lymphocytic arrangement in the spleen of Bufo calamita corresponds to a follicular model and is similar to that reported in the primitive anurans of the Pipidae family, such as Xenopus laevis. The white pulp presents a reticular network consisting of two different cell types and free cells, such as lymphocytes, plasma cells, and macrophages. The red pulp is formed by cell cords, where reticular cells and fibers, macrophages and lymphocytes occur, and blood sinuses which some times contain developing erythroid elements. Colloidal carbon particles injeced via the lymph sac are trapped exclusively by free macrophages in the red pulp which then move through the marginal zone to the white pulp. Giant, ramified, non‐phagocytic cells appear in both white and red pulp. They have been functionally related with the trapping of antigen‐antibody complexes on their surface, and a possible dendritic significance is discussed on the basis of their morphologic characteristics.
Three‐dimensional reconstruction of a rat stage V Sertoli cell: III. A study of specific cellular relationships
Authors: Russell Lonnie D. , Tallon‐Doran Maureen , Weber James E. , Wong Vivien , Peterson R. N. 
Published: February 2005

AbstractSpecific Sertoli–Sertoli and Sertoli–germ‐cell contacts and/or junctions were investigated employing micrographs used to reconstruct serially a model of a rat stage V Sertoli cell. The Sertoli–Sertoli junctional contact areas occurred in a belt‐like arrangement near the base of the Sertoli cell. This configuration is consistent with their proposed function as a sealing element limiting the passage of materials toward the tubular lumen. Sertoli ectoplasmic specializations also formed a continuous belt, or band, around the reconstructed cell at the junctional contact area. Eighteen Sertoli–Sertoli tubulobulbar complexes were found; some (12 in number) invaginated the reconstructed cell, while others (6) emanated from it. Of 37 round germ cells that were sectioned in their entirety and adjoined the reconstructed cell, 23 displayed desmosome–gap junctions with either the reconstructed cell or an adjoining cell. Since there were multiple junctions connecting some germ cells to Sertoli cells, the total number of junctions was much greater (35). Desmosome–gap junctions of the Sertoli cell were numerous connecting pachytene spermatocytes, less numerous connecting type B spermatogonia, and even less numerous connecting step 5 spermatids; and none was seen joining Sertoli cells with elongate spermatids. Most desmosome‐gap junctions join germ cells to the body of the Sertoli cell at its basal aspect. Their numbers and position indicate that they play a role in the maintenance of the integrity of the seminiferous epithelium and may provide a route for cell‐to‐cell communication. Ectoplasmic specializations of the reconstructed cell were seen facing only 3 of 37 round germ cells, and 7 ectoplasmic specializations from adjoining Sertoli cells faced these germ cells, all of which were step 5 spermatids. That there were no ectoplasmic specializations facing pachytene cells indicates that ectoplasmic specializations are not acquired as these cells pass through Sertoli–Sertoli junctions, but are acquired later in spermatogenesis.
Histochemical studies on the distribution of thiamine pyrophosphatase and enzymes related to carbohydrate metabolism in the intercalated neurons of the rat supraoptic nucleus
Authors: Iijima Koichi , Saito Hitoshi 
Published: February 2005

AbstractHistochemical studies have been conducted by applying hexokinase (HK), aldolase (AD), glyceraldehyde‐3‐phosphate dehydrogenase (G3), succinate dehydrogenase (SDH), glucose‐6‐phosphate dehydrogenase (G6PD), and thiamine pyrophosphatase (TPPase) methods, as well as Nissl staining and Gomori's chrome‐alum‐hematoxylin‐phloxine (CHP) methods to intercalated neurons of the supraoptic nucleus (SO) on Wistar strain rats. Intercalated neurons reacted weakly to the AD, G3, G6PD, and SDH tests, indicating that they belong to the category of ordinary neurons with low carbohydrate metabolism. Many fibrous astrocytes showing strong HK reactions surround neurosecretory neurons. However, they do not surround intercalated neurons with mild HK activity. These results indicate that the latter receive a poor supply of energy from glucose in the circulating blood in contrast to the former. Intercalated neurons are very rich in Nissl substance but lack CHP‐positive material. They may have a high potential for synthesizing protein. The principal morphological features of the TPPase‐positive Golgi material are peculiar and heterogeneous shape and poor development. These findings together with mild G6PD activity suggest that intercalated neurons are very likely to have poor synthesizing activity.
Several cytokinetic methods for showing circadian variation in normal murine tissue and in a tumor
Authors: Rubin N. H. , Hokanson J. A. , Mayschak J. W. , Tsai T. H. , Barranco S. C. , Scheving L. E. 
Published: February 2005

AbstractCircadian rhythmicity in cell proliferation was studied by several cytokinetic techniques in 8‐week‐old CD2F1 and Swiss male mice. In separate experiments on four different dates, subgroups of six or seven mice (fed ad libitum and standardized to 8 hours light alternating with 16 hours of darkness) were killed at 3‐hour intervals over a period of 24–48 hours. Cosinor analyses were used to determine the parameters of circadian periodicity in the data. Flow cytometric (FCM) analyses of DNA synthesis in tongue and stomach were compared with estimates of tritiated thymidine (3HTdR) incorporation into the DNA in these tissues. Circadian variation in tongue epithelium was reproducible in phasing and in range‐of‐change (100–140%) in seven 24‐hour studies. The proportion of cells in G1 and G2 in tongue epithelium also demonstrated a circadian periodicity. When DNA synthesis in stomach was analyzed by the two methods, the results were entirely different and thus not comparable. The circadian rhythms in 3HTdR uptake agreed with those reported previously, but results of analyses by FCM were less certain, since epithelium of this organ could not be analyzed separately. Circadian rhythms were detected by FCM in G1, S, and G2M in Ehrlich ascites carcinoma (EAC). The mitotic index of this tumor varied with a circadian periodicity similar to that of the FCM‐derived rhythm in G2M. This study validates the reliability of older techniques, such as 3HTdR uptake and mitotic indices, and suggests that circadian rhythms can be important in studies of cellular properties using FCM.
Abnormal hepatic lipid accumulation following treatment of diabetic rats with insulin and a high‐carbohydrate, fat‐free diet
Authors: Drake Richard L. , Thompson Ed W. , Parks William C. 
Published: February 2005

AbstractThis study correlates the morphological and biochemical events during the accumulation of hepatic lipids in diabetic rats in response to insulin treatment and a high‐carbohydrate, fat‐free diet. Alloxan‐diabetic rats were fed a high‐carbohydrate, fat‐free diet and treated with insulin for 12, 36, or 60 hr or 4.5 or 6.5 days. Samples of livers were obtained for determination of malic enzyme activity and the histochemical demonstration of lipids. An increased accumulation of hepatic lipids, although delayed, was observed following insulin treatment of diabetic rats fed the special diet. Small lipid droplets were visible after 36 hr of treatment, which later increased and coalesced into larger droplets present in all hepatocytes. Maximal accumulation was observed at 4.5 days of treatment. These changes were paralleled by an increase in the activity of hepatic malic enzyme. By 6.5 days of treatment, the lipid content of the hepatocytes had decreased and a periportal pattern was discernible. In contrast, malic enzyme activity continued to increase through 6.5 days of treatment. By comparison, no hepatic lipid accumulation occurred in regular chow‐fed diabetic rats receiving insulin treatment or in diabetic rats placed on the special diet alone. These results suggest that the combination of insulin treatment and a high‐carbohydrate, fat‐free diet caused an imbalance in the production and mobilization of hepatic lipids.