bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the vasculature of the pars distalis in a tumor‐susceptible strain of rat (Fischer 344) differs from vascular development in a non‐tumor‐susceptible strain (Lewis)
Authors: Schechter Joel E. 
Published: February 2005

AbstractThe development of the vasculature of the pars distalis of two strains of rat, Fischer 344 (F344) and Lewis (LEW), was followed in 16‐day (16d) and 20‐day (20d) fetuses, and in 1‐day (1d), 5d, 20d, 50d, and 6‐month‐old females. No differences in the two strains were apparent in 16d fetuses; and the capillaries that were present were immature, i.e., tall, non‐fenestrated endothelial cells, and were surrounded by poorly delineated pericapillary spaces. Immature capillaries also were predominant in 20d fetuses of both strains. Agranular folliculo‐stellate cells were identifiable, projecting endfeet to the parenchymal basal lamina in 20d F344 fetuses, but not in LEW fetuses.Postnatally, the capillaries of LEW rats became progressively more thin‐walled and fenestrated, and were surrounded by a pericapillary space that was well delimited by basal laminae at 20d. In 50d and 6‐month LEW rats, capillaries were intact and surrounded by well‐defined pericapillary spaces. By comparison in F344 rats, the capillaries remained more immature even in 50d rats and older. In addition, in F344 rats focal disruptions in endothelial cells and disruptions in parenchymal and capillary basal laminae were present in all postnatal stages, and a dramatic accumulation of plasma was evident within the pericapillary spaces at 20d. Endfeet processes of folliculo‐stellate cells were abundant at the parenchymal basal lamina of 1d and 5d F344 neonates, but only rarely were identified in LEW neonates. Some activation of folliculo‐stellate cells, i.e., increased numbers of lysosomes and dilated endoplasmic reticulum, was present in 50d F344 rats. Connective‐tissue cells within the pericapillary space also were numerous and activated in F344 rats. Discrete gaps in the parenchymal basal lamina were evident subjacent to the folliculo‐stellate cell endfeet in F344 rats but not in LEW rats.The vascular bed of F344 rats differs in its development from that of LEW rats. Characteristic of the F344 strain is a persistence of more immature capillaries, an inherent vascular fragility, and an activated state of folliculo‐stellate cells.
Macrophage mobilization and morphology during lens regeneration from the iris epithelium in newts: Studies with correlated scanning and transmission electron microscopy
Authors: Reyer Randall W. 
Published: February 2005

AbstractThe lens was removed from both eyes of adult newts (Notophthalmus viridescens), and the eyes were fixed in Karnovsky's fixative every 2 days 0–20 days after operation. Anterior half‐eyes were prepared by standard procedures for scanning electron microscopy of the surface. Before fixation, the posterior iris surface was cleaned of adhering vitreous mechanically with forceps or by treatment with bovine testicular hyaluronidase or with hyaluronidase and collagenase. Some specimens were cryofractured in buffer or ethanol transverse to the mid‐dorsal iris, and the fractured surface viewed with scanning electron microscopy (SEM).Cells with various combinations of ridges, blebs, filopodia, and lamellipodia were observed adhering to the posterior surface of the iris by 6 days after lentectomy. These cells, which exhibited the surface characteristics of macrophages, became more numerous in specimens fixed after longer intervals. Invasion of the iris epithelium was observed in a cryofractured specimen. After observations with SEM, selected specimens were embedded in plastic and sectioned for study with transmission electron microscopy (TEM). The cells on the iris surface had the cytological characteristics of macrophages, and other macrophages were located within the iris epithelium. In specimens fixed 16 or more days after lentectomy, a bulging lens vesicle was regenerating from the dorsal pupillary margin of the iris. Macrophages were absent or few on the surface of this developing lens but remained scattered over the adjoining iris.Roles that might be played by these macrophages during the transdifferentiation of iris epithelium into lens are discussed.
Three‐dimensional analysis of erythrophagosomes in rat mesenteric lymph node macrophages
Authors: Sasaki Katsunori 
Published: February 2005

AbstractErythrocytes extravasated into the sinuses of the rat mesenteric lymph nodes as a result of short‐term clamping of the portal vein were, although autologous, phagocytized markedly by the lymph node macrophages at 1 hr after reopening of the vein. The erythrophagosomes formed in the macrophages were exposed three dimensionally by the cellular matrix maceration method and observed with a high‐resolution scaning electron microscope. These results were compared to those obtained by conventional transmission electron microscopy. The process of degradation of an erythrocyte took about 6 hr. Coated pits were formed on the erythrophagosomal membrane at the early stage, and the erythrophagosomes were degraded by two different pathways: (1) the degradative pathway by invaginations of the phagosomal membrane, through which the erythrophagosome shrank and broke into secondary lysosomes, and (2) the hemolytic degradative pathway, by which it lost its content and formed a ghost.
Variability of measurements of cranial growth in the rabbit
Authors: Alberius Per , Malmberg Martin , Persson Sven , Selvik Göran 
Published: February 2005

AbstractThis study concerns techniques used in experimental cranial growth research: roentgen cephalometry, roentgen stereophotogrammetry, and gross measurements (osteometry). A comparison of the precision of these methods has not been found in the literature. Computation of technical errors is fundamental to the sound evaluation of registered findings, and such a presentation must be obligatory in all biometric reports. We compared the measurement error of roentgen cophalometric and osteometric data with that obtained by roentgen stereophotogrammetry (RSA). RSA demonstrates a superior replicability, and this technique gives possibilities for kinematic and volumetric determinations simultaneously with distance evaluation. Roentgen cephalometry has the advantage of enabling distance and angular measurements between any well‐defined skeletal points or lines. This technique, preferably after implantation of bone markers, is a reliable alternative, but optimal results necessitates calculations of the magnification factor for each bone segment involved. Direct osteometry does not contribute additional information, but problems of image magnification are omitted. Preferably, one individual should perform all measurements regardless of the method used. Growth rates and values calculated by one technique cannot be directly transformed to some other approach. In all probability, assessments of distance changes would gain substantially by using one technical approach consistently throughout actual age intervals. The least variable measurements of sutural growth are made for sutures growing primarily in one plane and with substantial growth rates. One must realize that differences among studies may be due to the limitations of, in particular, the cephalometric and osteometric techniques.
Expression of the epidermal growth factor receptor in developing fetal mouse palates: An immunohistochemical study
Authors: Shiota Kohei , Fujita Shigeuki , Akiyama Tetsu , Mori Chisato 
Published: February 2005

AbstractEpidermal growth factor (EGF) stimulates the growth of various tissues and, therefore, EGF receptor expression in fetal tissues may play a key role in organogenesis. We have examined immunohistochemically the ontogeny and localization of the EGF receptor in the fetal mouse palate during in vivo and in vitro palatogenesis using the anti‐human EGF receptor rabbit antibody. Immunoreactive products against the EGF receptor were observed in the palatal tissue examined on days 12, 13, and 14 of gestation. On days 12 and 13, the immunoreactive products were predominantly positive on the oral and medial edge epithelia but were minimal on the epithelium of the vertical shelf. The EGF receptor immunoreactivity was less intense in the posterior palate as compared with the midpalatal region. In the fusing palate of day 14 fetuses, the cells forming the midline epithelial seam were continuously positive for EGF‐R immunoreactivity. The mesenchyme of palatal shelves also showed regional heterogeneity and temporal sequence in EGF receptor expression. The localization of the EGF receptor in fetal mouse palates cultured in a serumless medium generally simulated that observed in vivo.
Labeling of hepatic glycogen after short‐ and long‐term stimulation of glycogen synthesis in rats injected with 3H‐galactose
Authors: Michaels John E. , Garfield Sanford A. , Hung Julia T. , Cardell Robert R. 
Published: February 2005

AbstractThe effects of short‐and longterm stimulation of glycogen synthesis elicited by dexamethasone were studied by light (LM) and electron (EM) microscopic radioautography (RAG) and biochemical analysis. Adrenalectomized rats were fasted overnight and pretreated for short‐ (3 hr) or long‐term (14 hr) periods with dexamethasone prior to intravenous injection of tracer doses of 3H‐galactose. Analysis of LM‐RAGs from short‐term rats revealed that about equal percentages (44%) of hepatocytes became heavily or lightly labeled cells increased slightly 6 hr after labeling, and unlabeled glycogen became apparent in some hepatocytes. The percentage of heavily labeled cells had decreased somewhat 12 hr after labeling, and more unlabeled glycogen was evident. In the long‐term rats 1 hr after labeling, a higher percentage of heavily labeled cells (76%) was observed compared to short‐term rats, and most glycogen was labeled. In spite of the high amount of labeling seen initially, the percentage of heavily labeled hepatocytes had decreased considerably to 55% by 12 hr after injection; and sparsely labeled and unlabeled glycogen was prevalent. The EM‐RAGs of both short‐ and long‐term rats were similar. Silver grains were associated with glycogen patches 1 hr after labeling; 12 hr after labeling, the glycogen patches had enlarged; and label, where present, was dispersed over the enlarged glycogen clumps. Analysis of DPM/mg tissue corroborated the observed decrease in label 12 hr after adminstration in the long‐term animals. The loss of label observed 12 hr after injection in the long‐term pretreated rats suggests that turnover of glycogen occurred during this interval despite the net accumulation of glycogen that was visible morphologically and evident from biochemical measurement.
Defective osteoclast differentiation and function in the osteopetrotic (os) rabbit
Authors: Lenhard Sharon , Popoff Steven N. , Marks Sandy C. 
Published: February 2005

AbstractWe tested the ability of normal osteoclast progenitors found in neonatal liver and bone marrow to develop into functional osteoclasts when co‐cultured with metatarsals from newborn osteopetrotic rabbits; the latter inherit an osteoclast incompetence resistant to cure by bone marrow transplantation. This system, developed by Burger and colleagous, has been shown to produce normal, functional osteoclasts when used with normal metatarsals. Our study tested the competence of the mutant skeletal microenvironment for differentiation of normal osteoclasts. Mutant and normal metatarsals were cultured alone or with normal liver, spleen, or bone marrow for up to 14 days. All normal cultures possessed a marrow cavity and contained numerous osteoclasts with cytochemical characteristics (tartrateresistant acid phosphatase) of active cells. Mutant metatarsals co‐cultured with normal spleen, liver, or bone marrow failed to develop a marrow cavity (evidence in itself of reduced bone resorption) and had osteoclasts reduced in both numbers and cytochemically detectable activity. Similar metatarsal cultures of an osteopetrotic rat mutation (incisors–absent) curable by bone‐marrow transplantation exhibited marrow cavity development in mutant metatarsals co‐cultured with normal spleen. These data suggest that the skeletal environment of osteopetrotic rabbits contains an inhibitor or lacks a promoter of osteoclast differentiation and function.
Nucleolar structure and synthetic activity during meiotic prophase and spermiogenesis in the rat
Authors: Schultz Michael C. , Leblond C. P. 
Published: February 2005

AbstractThe ultrastructure of nucleoli was examined in developing rat spermatocytes and spermatids, with the help of serial sections. In addition, the radioautographic reaction of nucleoli was examined in rats sacrificed 1 hr after intratesticular injection of 3H(5′)‐uridine and taken as an index of the rate of synthesis of ribosomal RNA (rRNA).Primary spermatocytes from preleptotene to zygotene have small nucleoli typically composed of fibrillar centers, a fibrillar component, and a granular component, within which are narrow interstitial spaces. During early and mid‐pachytene, nucleoli enlarge to about nine times their initial size, with the fibrillar and granular components forming an extensive network of cords—a nucleolonema—within which are wide interstitial spaces. Meanwhile, there appear structures identical to the granular component but distinct from nucleoli; they are referred to as extranucleolar granular elements. Finally, from late pachytene to the first maturation division, nucleoli undergo condensation, as shown by contraction of fibrillar centers into small clumps, while fibrillar and granular components condense and segregate from each other, with a gradual decrease in interstitial spaces. In secondary spermatocytes, nucleoli are compact and rather small, while in young spermatids they are also compact and even smaller. Nucleoli disappear in elongating spermatids.In 3H‐uridine radioautographs, nucleolar label is weak in young primary spermatocytes, increases progressively during early pachytene, is strong by the end of mid pachytene, but gradually decreases during late pachytene up to the first maturation division. In secondary spermatocytes and spermatids, there is no significant nucleolar label.In conclusion, rRNA synthesis by nucleoli is low in young spermatocytes. During pachytene, while nucleoli enlarge and form a lacy nucleolonema, rRNA synthesis increases gradually to a high level by the end of mid pachytene. However, during the condensation and segregation of nucleolar components occurring from late pachytene onward, the synthesis gradually decreases and disappears. The small, compact spermatids arising from the second maturation division do not synthesize rRNA.
A morphologic study of bronchus‐associated lymphoid tissue in turkeys
Authors: Fagerland Jane A. , Arp Lawrence H. 
Published: February 2005

AbstractBronchus‐associated lymphoid tissue (BALT) in normal turkeys of ages 1 day and 1, 2, 3, 4, 8, and 18 weeks was examined by light microscopy and by scanning and transmission electron microscopy. Turkey BALT resembled other mucosa‐associated lymphoid tissues; it was made up of a population of lymphocytes covered by a specialized epithelium different from typical pseudostratified ciliated columnar bronchial epithelium. There were distinct age‐related differences in BALT structure. Bronchus‐associated lymphoid nodules were larger and more numerous in older turkeys. In 1‐day‐ to 2‐week‐old turkeys, the primary cell type of BALT epithelium was nonciliated cuboidal; in 2‐week old turkeys it was squamous; and in turkeys older than 4‐weeks of age, the epithelium was primarily ciliated columnar. In 1‐ to 4‐week old turkeys, large numbers of intraepithelial lymphocytes disrupted the normal organization of the epithelium. In older turkeys, epithelial and lymphoid cells were in discrete compartments separated by connective tissue. Lymphocytes in 1‐day‐old turkeys were found in loose aggregates around venules and within the epithelium. In 1‐week old turkeys, lymphocytes were organized into compartments of morphologically similar cells. By 3‐weeks of age, lymphocytes were present in distinct germinal centers. Epithelial cells of BALT did not have large numbers of apical vesicles and thus were not structurally specialized for antigen uptake by endocytosis. However, the epithelial barrier appeared to be disrupted over lymphoid nodules, suggesting that antigen would be readily available to lymphocytes and phagocytes in BALT. Age‐related differences in turkey BALT structure may have functional consequences with respect to the respiratory immune response.
Morphometric analysis of vertebrae and intervertebral discs as a basis of disc replacement
Authors: Aharinejad S. , Bertagnoli R. , Wicke K. , Firbas W. , Schneider B. 
Published: February 2005

AbstractIn this study measurements were obtained from 359 vertebrae and 215 intervertebral discs in an attempt to classify discs by their size. At the cervical and thoracic levels, this attempt was unproductive because of extensive variations. In the lumbar spine, discs were allocated to six size‐matched groups. The breadth of marginal rims were also measured with a view to provide surgeons operating on the spine with precise data on disc morphology to facilitate dise replacement.
Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats
Authors: Byrd Kenneth E. , Stein Stephen T. , Sokoloff Alan J. , Shankar Kavita 
Published: February 2005

AbstractThe objective of this study was to define further the role of the trigeminal motor nucleus (TMNu) in the postnatal ontogeny of the mammalian craniofacial skeleton. To that end, 42 male Sprague‐Dawley rats underwent stereotaxic surgery at 40 days of age; 21 received small electrolytic lesions to their left‐side TMNu (lesioned group) while 21 had TMNu stimulation with no actual electrolytic lesion produced (sham group). Seven rats from each group were killed at 28, 56, and 84 days postoperative to analyze trigeminal motoneuron (TMNe) count, masticatory muscle weight, and osteological growth vector data. At all three time periods, lesioned animals showed significant differences (1) between the surgery and nonsurgery sides, and (2) from sham animals. However, sham animals also demonstrated significant between‐side differences for medial pterygoid muscle weight (56 days), mandibular height (28 and 56 days), and mandibular length data (84 days); these data suggested that even relatively slight damage to TMNe can create morphological changes within the craniofacial complex. Snout deviation in a lesioned rat towards the opposite side from all other lesioned animals was correlated with unique damage to its pontine reticular formation; this suggested that the observed morphological alterations of the craniofacial complex may have been due not only to TMNu damage, but also to changed expressions of the masticatory central pattern generator (CPG). Morphological alterations of the craniofacial skeleton resulting from lesions to the TMNu were likely due to changed neuromuscular activity patterns of the masticatory muscles and their biomechanical effects upon bone.
Blood vascular network of the rat lymph node: Tridimensional studies by light and scanning electron microscopy
Authors: Bélisle C. , Sainte‐Marie G. 
Published: February 2005

AbstractMany aspects of the blood vascular network of the lymph node are unknown, and others need confirmation. We have studied the blood vasculature of rat peripheral lymph nodes by means of carbon perfusion and vascular cast corrosion techniques. At the hilus of the node, an artery gives off arterioles running in medullary cords towards the cortex. Some reach the peripheral cortex directly, branching there into slender cortical vessels. Other arterioles enter the periphery of the deep cortex units, and then head towards the peripheral cortex. Upon reaching it, they curve part way above the center of the deep cortex units and provide slender branches to the overlying peripheral cortex. Dense plexuses of capillaries arise from arterioles in the medullary cords, in the periphery of the deep cortex units, and in the outermost stratum of the extrafollicular zone of the peripheral cortex. In the cortex, the draining high endothelial venules are restricted to the extrafollicular zone and to the periphery of the deep cortex units. At the cortico‐medullary junction, these peculiar venules transform into regular medullary venules which form the hilar veins. In contrast, the folliculo‐nodules and center of the deep cortex units are little vascularized by a loose capillary network, while no vessels occur in the subsinus layer. These features of the node vascular network are of interest in relation to the node architecture.
The human rhombencephalon at the end of the embryonic period proper
Authors: Müller Fabiola , O'Rahilly Ronan 
Published: February 2005

AbstractThe human rhombencephalon at 8 postovulatory weeks (stage 23) is described and illustrated for the first time with the aid of silver‐impregnated sections and graphic reconstructions. The motor and sensory trigeminal nuclei were among those studied, and the latter was found to be almost contiguous to the dentate nucleus. Fibers to the principal sensory nucleus join the mesencephalic trigeminal tract, which also seems to be connected with the motor fibers. Fine fibers from the sensory root join the tractus solitarius, which appears to receive connections from the facial, glossopharyngeal, and vagal nerves. Main and accessory abducent nuclei are evident. A part (the Kappenkern des Facialisknies) of the nucleus funiculi teretis is particularly prominent. The presence of the pyramidal decussation during the embryonic period is noted for the first time. The arrangement of nuclei and tracts at 8 weeks is shown to be closely similar to that present in the newborn, and it is likely that the rapid growth of the rhombencephalon during the embryonic period proper is associated with correspondingly early functional activity.
Auditory epithelial migration on the human tympanic membrane: II. The existence of two discrete migratory pathways and their embryologic correlates
Authors: Michaels Leslie , Soucek Sava 
Published: February 2005

AbstractThe pathways of movement of dye‐markings on the tympanic membranes of 30 ears of 15 volunteers were investigated by photography with a Hopkin's rod. Two discrete pathways were identified. Movement on the pars tensa was centrifugal in all directions from the edge of the handle of malleus surface. This supported our previous suggestion that pars tensa epithelial migration is based on growth of the meatal plate. Movement on the more central part of the handle surface itself, however, was always upwards to the pars flaccida epithelium and then, with all dye on the latter, in a posterosuperior direction only.The covering epithelium of the pars flaccida/handle of malleus arises from the fundus of the early embryonic external canal. To explore the possibility that its migration may also commence early, the fundus was examined histologically in 12 embryo ears. It was shaped like an inverted pear to conform to the primordial head of the malleus above and its handle below. There was distinct flattening of the whole fundal epithelium in contrast to the side wall of the external canal, lending support to the concept of a primordial flux of epithelium in the main fundus and its inferior extension. The meatal plate grew from the rim of the fundus producing the pars tensa and deep external canal epithelia. This process, however, was not associated with significant cytologic alterations or increased expression of the human proliferation antigen, Ki‐67, at that rim. This suggests that the pars tensa epithelium grows and moves without the active involvement of the epithelium of the pars flaccida/handle of malleus.