bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cartilaginous bone extremities of growing monotremes appear unique
Authors: Thorp B. H. , Dixon J. M. 
Published: February 2005

AbstractCartilage canals are present in the epiphyseal cartilage of most mammals and birds. They are considered necessary for the maintenance of chon‐drocytes and for the formation of epiphyseal ossification centers. The epiphyseal cartilage of marsupials was recently shown not to contain cartilage canals, and placental rats appear not to have cartilage canals, although some confusion exists in the literature. The present study examines the cartilaginous epiphyses and physes from the knee and hip of the rat and the two Australian monotremes (platypus, Ornithorhynchus anatinus and echidna, Tachyglossus aculeatus). In all three species, cartilage canals were absent. Vessels to epiphyseal ossification centers were present, however. In the center of the cartilaginous femoral head of the echidna, but not in the platypus or rat, there was a large cavity, which contained connective tissue and was lined by an endochondrium of chondroproginator cells. These appeared to be contributing to growth of the cartilaginous epiphysis. No similar structure has previously been described in the cartilaginous epiphysis of other species. There was no ligament of the femoral head in the hip joints of the monotremes, and it is suggested the absence of a ligament may be significant in the development of the cavity. It was noted in all specimens that despite being avascular the epiphyseal and physeal cartilage appeared viable and functionally normal. The small size of the cartilaginous epiphyses of the rat may account for their avascularity; but the epiphyses of the monotremes were much larger, especially the echidna, yet still avascular. These features provide strong evidence for fundamental differences between the avascular cartilage of monotremes and the vascular cartilage of most mammals.
Pulmonary development in the fetal lamb: Morphometric study of the alveolar phase
Authors: Docimo Steven G. , Crone Robert K. , Davies Paul , Reid Lynne , Retik Alan B. , Mandell James 
Published: February 2005

AbstractThe alveolar stage of intra‐uterine lung development was analyzed morphometrically in 18 fetal lambs at 112, 124, 142, or 148 (term) days of gestation. The right lungs were fixed at uniform distending pressure and the tissue embedded in Epon for light microscopy. Over the whole period, right lung volume (VL) increased more rapidly than body weight to reach a mean value of 185 cm3 at term. The increase in VL was greatest between 112 and 124 days gestation. Throughout the period of study the distal lung consisted of alveolar‐like air‐spaces lined by walls with a single capillary system. Despite this mature morphology, further differentiation took place as established by two independent measurements. First, interalveolar wall thickness decreased from 4.12 ± .03 μm at 112 days to 2.55 ± .02 μm at term. Secondly, alveolar surface area increased at a greater rate than lung volume (as VL 1.06), suggesting a moderate increase in surface complexity, but not a subdivision of existing air‐spaces. This latter finding was supported by numerical density values which remained fairly constant. We conclude that throughout this period active growth involves the addition of alveolar units of basically similar size. This is a similar process to the one noted previously in postpneumonectomy compensatory growth.
On the question of a subdural space
Authors: Haines D. E. 
Published: February 2005

AbstractThe structure of the meninges, with particular attention to the architecture of the inner portions of the dura mater and the arachnoid mater, has been reviewed in reference to the probable existence of a “subdural” space. The dura is composed of fibroblasts and large amounts of extracellular collagen. The innermost part of the dura is formed by the dural border cell layer. This layer is characterized by flattened cells with sinuous processes, extracellular spaces containing an amorphous material, and the presence of junctions between its cells. The dural border cell layer is continuous with the inner (meningeal) portions of the dura and may be attached to the underlying arachnoid by an occasional cell junction. The arachnoid consists of an outer part, the arachnoid barrier cell layer, and an inner portion, the arachnoid trabeculae which bridge the subarachnoid space. Arachnoid barrier cells are electron‐lucent, closely apposed to each other, and joined by many cell junctions; in this layer there is little extracellular space and essentially no intercellular material. Arachnoid trabecular cells cross the sub‐arachnoid space in a random manner, have extracellular collagen associated with their flattened processes, and form structures of variable shapes and sizes. There is no evidence of an intervening space between the arachnoid barrier cell layer and the dural border cell layer that would correlate with what has been called the subdural space. When a tissue space is created in this general area of the meninges it is the result of tissue damage and represents, in most instances, a cleaving open of the dural border cell layer. In this situation, extracellular spaces in the dural border cell layer are enlarged, cell junctions are separated, and it is probable that cell membranes are damaged. A survey of reports describing the morphology of the inner and outer capsule of so‐called subdural hematomas in humans reveals that dural border cells are found in both parts of the capsule. Also, experimental infusion of blood into this portion of the meninges in animals frequently dissects open the dural border cell layer. These data support the view that what has been called a subdural hematoma is most frequently a lesion found within the layer formed by dural border cells.It is suggested that the so‐called subdural space is not a “potential” space since the creation of a cleft in this area of the meninges is the result of tissue damage. In this respect it shares no similarities with legitimate potential spaces (i.e., serous cavities) found at other locations in the body. It is concluded that there is no evidence of a subdural space (actual or potential) in the region of the dura‐arachnoid junction and it is suggested that the term spatium subdurale be removed from Nomina Anatomica.
Multiple growth cartilages in the neural arch
Authors: Chandraraj Seba , Briggs Christopher A. 
Published: February 2005

AbstractThe origin of growth cartilages in the neural arch of human fetal vertebrae was investigated in an attempt to resolve the conflicting opinion on ossification in this region. Serial sections of developing vertebrae were examined, and three growth cartilages for each half of the neural arch were found. They have their origin from a single center of ossification. Endochondral bone formation similar to ossification in the diaphysis of a long bone occurs in the neural arch. This information may help in the understanding of how vertebral malformations such as scoliosis and spondylolysis occur during postnatal life.
Development of esophageal epithelium in the fetal and neonatal mouse
Authors: Raymond Calvert , Anne Vézina , Millane Ghania 
Published: February 2005

AbstractDevelopment of the fetal mouse esophageal epithelium was followed using light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and radioautography. At 15 days of gestation in the cervical (C), mediastinal (M), and abdominal (A) segments of the esophagus, the epithelium was two or three cells thick, and only cells located in the basal (germinal) layer incorporated tritiated thymidine. Ciliated cells were sparse in all three segments. At 17 days of gestation, longitudinal mesenchymal ridges became more differentiated in the distal segment. Labeling indices were lower than at preceding stages in each segment. Ciliated cells had increased in number and appeared to be evenly distributed along the whole esophagus. In periodic acid‐Schiff (PAS)‐stained sections, an increasing proximodistal distribution of glycogen stores was observed, with greatest concentrations found in segment A. At 18 days of gestation, labeling indices were comparable in segments C and M (11.7% ± 2.9% and 12.8% ± 1.9%, respectively) but remained higher in segment A (17.9% ± 2.0%). Ciliated cells were still present. At this stage, transverse circular furrows and ridges started to appear. They increased in number at 4 days after birth and were very closely distributed in the adult. In longitudinal sections, these ridges corresponded to projections of stratum granulosum and of the overlying stratum corneum. After birth, ciliated cells desquamated rapidly but some patches were still present at 4 days. At 8 days, the esophageal epithelium was not yet keratinized.
Composition of myofiber types in the pectoral girdle musculature of sheep
Authors: Suzuki Atsushi 
Published: February 2005

AbstractThe muscles of the pectoral girdle in domestic animals attach the forelimbs to the trunk and function as the suspensory apparatus. In the present study the composition of the pectoral girdle musculature of sheep by myofiber types was examined. Myofibers showing a strong reaction for alkali‐stable myosin ATPase were classified into fast‐twitch/glycolytic (FG) myofibers with a weak activity for NADH tetrazolium reductase (NADH‐TR) and fast‐twitch/oxidative/glycolytic (FOG) myofibers with a moderate and strong NADH‐TR activity. Myofibers showing a weak reaction for alkali‐stable myosin ATPase and a strong activity for NADH‐TR were classified as slow‐twitch/oxidative (SO) myofibers. The SO myofibers that showed a granular and striped pattern of diformazan deposits in NADH‐TR activity were classified as SO‐1 myofibers, whereas the SO myofibers characterized by a reticular pattern of diformazan deposits were classified as SO‐2 myofibers. The trapezius, rhomboideus cervicis, and pectoralis descendens muscles situated superficially in the cranial regions of the back and chest had about 50% SO (SO‐1 plus SO‐2) myofibers. The deeply situated serratus ventralis cervicis and thoracis muscles had 37.5% SO myofibers. These five muscles included more SO‐2 myofibers with large diameters than did all other muscles, and had about 50% and more cross‐sectional area of SO myofibers. The other muscles had less than 32% SO myofibers and fewer SO‐2 myofibers. The FOG and FG myofibers accounted for 50% or less in the muscles examined. Many muscles of the pectoral girdle had many fast‐twitch (FOG plus FG) myofibers; they seem to meet locomotory requirements. In the pectoral girdle musculature, the SO myofibers were not necessarily distributed more in the deep regions than in the superficial regions. The distribution of SO myofibers appears to meet postural requirements for stabilizing the shoulder and brachium and for supporting the trunk.
Correlation between blood‐testis barrier development and onset of the first spermatogenic wave in normal and in busulfan‐treated rats: A lanthanum and freeze‐fracture study
Authors: Cavicchia Juan C. , Sacerdote Fabio L. 
Published: February 2005

AbstractPregnant rats (day 13) received 10 mg/kg of Busulfan i.p. The seminiferous tubules of their offspring from post‐natal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze‐fracture techniques. During this period, the inter‐Sertoli tight junctions of controls increase both in number and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes surrounded by tracer. The inter‐Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene‐pachytene stages. The tracer is stopped at the inter‐Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes. Freeze‐fracture shows that the orientation of inter‐Sertoli junctions has changed to parallel, both to each other and to the basal lamina. In the Busulfan‐treated rats, the tubules continue having, up to post‐natal day 30, only Sertoli cells and scanty spermatogonia. In these, lanthanum penetration goes as far as the apical Sertoli cell region; the inter‐Sertoli junctions still show tortuous strands, and most are oriented perpendicular to the basal lamina. This indicates that formation of the first competent inter‐Sertoli junctions is temporo‐spatially simultaneous with the appearance of zygotene‐pachytene spermatocytes.
Biomechanical changes in the rabbit masticatory system during postnatal development
Authors: Langenbach Geerling E. J. , Weijs Wim A. , Koolstra Jan Harm 
Published: February 2005

AbstractUsing dissection, biometry, and two three‐dimensional mechanical models, the postnatal changes of the rabbit masticatory muscles were studied by analyzing their three‐dimensional orientation, their strength and fiber lengths, and certain functional consequences of these changes. The first mechanical model uses length‐tension relationships of the muscles and predicts the maximum bite force as a function of mandibular position. It shows that young rabbits are able to generate large bite forces at a wider gape than adult animals and that the forces are directed more vertically. In spite of the postnatal changes the mechanical advantage of the system remains about equal. However, the muscles are reoriented so that they exert a larger degree of parallel action, suggesting a larger bite force magnitude but a smaller range of bite force directions. The second model predicts this range. It shows that during postnatal development a relative gain occurs in the possibilities for the system to exert forces directed rostrodorsally. In all other directions the capability to exert force decreases. The results suggest that during development the possibility of the system to generate large bite forces is increased at the cost of a restriction in the range of jaw excursion and that a restriction takes place in the range of possible force directions that can be exerted at the molars.
Endocytotic activity of the free floating cells and epithelial cells in the endolymphatic sac: An electron microscopic study
Authors: Fukazawa Keijiro , Sakagami Masafumi , Matsunaga Toru , Fujita Hisao 
Published: February 2005

AbstractThe fine structure and its functional properties of both free floating cells and epithelial cells in the endolymphatic sac after injections of India ink particles or polystyrene latex beads, 0.24 μm in diameter, into the endolymphatic space, were studied using light and electron microscopy. Twenty‐four to 48 hours after injections, these foreign materials had accumulated in the lumen of the endolymphatic sac and a large number of them were ingested into free floating cells, most of which appear to be macrophages. Granular leucocytes taking up the foreign materials into the cytoplasm were also recognized in the sac lumen. A few of these leucocytes passed through the epithelium and migrated to the subepithelial connective tissue, while the others were degenerated and phagocytosed by the free floating cells in the lumen of the sac. In addition to the free floating cells, ink particles, latex beads, and degenerated leucocytes were endocytosed into some of the epithelial cells. As we reported previously, the epithelial cells were clearly classified into two types; type‐1 epithelial cells (cytoorganelle‐rich cells) and type‐2 epithelial cells (filament‐rich cells). The foreign materials and degenerated cells were taken up mainly into the type‐1 epithelial cells, while the type‐2 epithelial cells did not show so marked endocytotic activity in comparison with the type‐1 epithelial cells. Thus, it becomes clear that the endolymphatic sac plays an important role in the endocytotic activity for foreign materials and waste products, and both the free floating cells and the type‐1 epithelial cells of the sac have strong endocytotic activity.
Age effects on cytochrome oxidase activities during denervation and recovery of three muscle fiber types
Authors: White Ketti K. , Vaughan Deborah W. 
Published: February 2005

AbstractThe rat nasolabialis muscle is comprised of a mosaic of red, white, and intermediate muscle fiber types. Using computerized microdensitometry, cytochrome oxidase (COX) activity was quantitatively analyzed in each fiber type throughout the period of denervation and recovery in young adult (3‐month) and middle‐aged (15‐month) male Sprague‐Dawley rats. In animals of both age groups, the nasolabialis muscle on one side of the head was denervated by crushing the facial nerve. At specific days post crush (dpc) ranging from 2 days–2 months, animals were sacrificed and thick sections of normal and denervated muscles were incubated to demonstrate the activity of COX, a mitochondrial enzyme, which differentiates between the three fiber types. Enzyme activities in individual fibers were microdensitometrically analyzed using a digitizing image analyzer. Although a denervation‐induced decrease followed by eventual recovery occurred in all fibers of each type, age‐related differences were evident. For all types, younger fibers consistently showed decreased COX activity sooner than their older counterparts, and older fibers of all types consistently showed a greater decreased COX activity than the younger fibers. Denervation‐induced de‐differentiation of muscle fibers led to a more homogeneous population of fiber types in both age groups. Following recovery of function, the magnitude of the fiber enzyme activity change differed according to fiber type and to age, and was consistently smaller in older animals. The normal mosaic pattern of fiber type distribution and normal COX levels were restored 2 months after nerve lesion in both age groups.
Origin and distribution of perforatorial proteins during spermatogenesis of the rat: An immunocytochemical study
Authors: Oko Richard , Clermont Yves 
Published: February 2005

AbstractThe perforatorium is the subacrosomal portion of the perinuclear theca that encapsulates the nucleus of spermatozoa. In the rat, the perforatorium is a curved pointed structure, which in cross section is triangular in outline over the apical half and beyond the tip of the nucleus. The perforatorium, composed of several proteins, appears as a distinct structural entity only at the very end of spermiogenesis. In this study, polyclonal antibodies prepared against the entire isolated perforatorial fraction and against the major 16 and 34 kDa perforatorial polypeptides were used to determine the distribution of perforatorial proteins in germinal cells at various steps of differentiation. Immunoperoxidase staining at the LM level and quantitative immunogold labeling at the EM level were used. The labeling patterns with all three antibody preparations were identical. The immunolabeling first appeared in early pachytene spermatocytes and increased progressively, with a statistically significant upward trend, in both the nuclei and cytoplasm of spermatocytes and spermatids until step 9 of spermiogenesis. Up to this step the labeling concentration was significantly higher over the nucleus than over the cytoplasm. During nuclear condensation in steps 9 and 12 spermatids, there was a progressive loss of all the labeling over the nucleus and a corresponding increase of labeling over the cytoplasm. During steps 16–18, the early signs of condensation of perforatorial proteins occurred next to the inner acrosomal membrane. Then during step 19 there was a sudden condensation of perforatorial proteins into a definitive perforatorium. Thus proteins destined to form this cytoskeletal structure reside in both the nucleus and cytoplasm of spermatocytes and spermatids until nuclear condensation of the latter. Thereafter, they are restricted to the spermatid's cytoplasm and finally condense around the elongated nucleus at the end of spermiogenesis.
Glycoconjugate histochemistry of Xenopus laevis fundic gland with special reference to mucous neck cells during development
Authors: Oinuma Tsutomu , Kawano Jun‐Ichi , Suganuma Tatsuo 
Published: February 2005

AbstractMucous neck cells (MNCs) of the fundic gland are phylogenetically thought to have first appeared in amphibians. We studied the origin and differentiaion of MNCs in fundic glands of Xenopus laevis. By means of lectin histochemical methods using Griffonia simplicifolia agglutinin‐II (GSA‐II), MNCs were detected specifically in fundic glands of adult X. laevis. Mucous granules of MNCs were labeled by GSA‐II‐colloidal gold (CG) staining. Other cells such as surface mucous cells (SMCs), oxynticopeptic cells (OPCs), and endocrine cells did not react to GSA‐II. Ulex europaeus agglutinin‐I specifically stained OPCs, but not MNCs and SMCs. During the morphogenetic period of the stomach in metamorphosing larvae, GSA‐II reactive cells randomly appeared in various portions of the underdeveloped fundic glands and then rapidly localized in the neck portion. At this time, newly appearing mucous granules of MNC type were labeled by GSA‐II‐CG. Two types of cells intermediate to MNCs and SMCs and intermediate to MNCs and OPCs were observed in the larval gastric region. Cells intermediate to MNCs and OPCs were also found in adults. In these cells, mucous granules of MNC type were labeled by GSA‐II‐CG, but mucous granules of SMC type and zymogen‐like granules did not react to GSA‐II. These observations suggest that GSA‐II is a useful marker in studying the differentiation of MNCs and their precursors regardless of species differentiation.
Morphological analysis of the cellular interaction between thymocytes and a thymic stromal cell line (TEL‐2)
Authors: Hirata Kazuho , Mori Keiko , Nakamura Keiichiro , Kawabuchi Masaru , Watanabe Takeshi 
Published: February 2005

AbstractIn a previous study (Nakashima et al., Eur. J. Immunol., 20: 47–53, 1990), a cloned stromal cell line TEL‐2 was established from Balb/c mouse thymus. Incubation of thymocytes with TEL‐2 cells resulted in the selective elimination of CD4 and CD8 double‐positive thymocytes from the culture. In the present report, both phase‐contrast and scanning electron microscopes were used to examine, at various time intervals, TEL‐2 cells cocultivated with thymocytes in order to elucidate the kinetic sequence of their cellular interaction. The thymocytes attached to the TEL‐2 cell surface were more numerous at early times (30 min to 1 h), and their number decreased gradually with time. In contrast, the thymocytes that migrated into the TEL‐2 cell layers were less abundant at early times, their number increasing with time thereafter. Destruction of the regular arrangement of TEL‐2 cells was found at later than 1 h, suggesting active cellular interaction. The thymocytes adherent to the TEL‐2 cell surface were found to be of various shapes and often showed variable profiles, e.g., extending small cytoplasmic processes along the surface of TEL‐2 cells or appearing ameboidal. A remarkable feature of the TEL‐2 cells was that they formed numerous “round spaces” at the surface of the TEL‐2 cell layers. The thymocytes were often located around “round spaces,” and some were seen migrating into TEL‐2 cell layers through these round spaces. In addition, complementary examinations by transmission electron microscopy revealed that the internalization of thymocytes into TEL‐2 cells occurs inside the TEL‐2 cell layers after migration. Thus, the present study confirmed the existence of a certain type of cellular interaction between thymocytes and TEL‐2 cells. The TEL‐2 cell line may provide a model system for the study of the selection mechanism in the process of T‐cell maturation.