bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphogenesis of the secondary palate in mouse embryos with special reference to the development of rugae
Authors: Sakamoto Michiko Kamimura , Nakamura Kosyo , Handa Jun , Kihara Takahide , Tanimura Takashi 
Published: February 2005

AbstractMorphological studies of secondary palate formation, with special reference to the development of rugae, were carried out on Jcl:ICR mouse embryos. Three rugae were observed on the anterior part of the future oral surface of the vertically developing palatal shelves in 13‐day embryos. Rugae increased in number as the development of the palatal shelves proceeded, and five to six prominent rugae were observed in 14‐day embryos just prior to shelf elevation. The folding of these five to six rugae progressed in conjunction with the formation of a sharp, valley‐like groove at the base of the anterior two‐fifths of the vertical palatal shelves. As palatal shelves elevated, the groove disappeared gradually, and, accordingly, the folding of rugae loosened. In the groove region, the superficial epithelial cells were roundish, while the basal ones were elongated. Such characteristic features were no longer observed when the disappearance of the groove was completed. Eight rugae were observed on the future hard palate of 14‐day embryos with already completed palatal fusion. An additional ruga was frequently found in 15‐day embryos, and the pattern then was almost the same as that of an adult. Epithelial thickening and condensation at the rugae region, as well as mesenchymal condensation under the epithelium of the rugae, were confirmed in embryos both before and after elevation of the palatal shelves. There is a possibility that structural characteristics observed in the epithelial and mesenchymal cells of the rugae and groove regions may be related to palatal shelf elevation.
Differential expression of galactose and N‐acetylgalactosamine residues during fetal development and postnatal maturation of rat glomeruli as revealed with lectin conjugates
Authors: Laitinen Liisa , Lehtonen Eero , Virtanen Iso 
Published: February 2005

AbstractA battery of fluorochrome‐ or peroxidase‐coupled lectins, reacting with α‐or β‐galactose (Gal), terminal N‐acetylgalactosamine (GalNAc), or Gal‐(β1‐3)‐GalNAc residues, was used to study the emergence and distribution of cellular glycoconjugates in developing and adult rat glomeruli. Neuraminidase pretreatment of the specimens was applied to monitor the maturation of the glomerular sialogly‐coprotein coat.In the adult glomeruli, the lectin conjugates applied reacted sparsely or not at all, but most of them showed an increased reactivity with podocytes and/or the glomerular basement membrane after neuraminidase treatment. In the embryonic glomeruli, lectins reacting with β‐Gal residues prominently bound to the basement membranes, as revealed in double‐staining with laminin antibodies. This reactivity decreased first during late postnatal development. Some terminal Gal‐(β1‐3)‐GalNAc residues were noted in the earliest podocytes, but obviously soon became covered by sialylation. Furthermore, the developing podocytes prominently displayed α‐Gal residues, as marked by Maclura pomifera (MPA) and Jacalin reactivities but not by the GSA‐I conjugates. During postnatal maturation these reactivities also decreased. The GalNAc‐specific Helix pomatia (HPA) and Helix aspersa (HAA) agglutinins bound to basement membranes of evolving podocytes but later revealed in the podocytes only a Golgi‐like cytoplasmic reactivity. These two lectins showed a marked difference in their binding to tubular basement membranes.In lectin blotting experiments of electrophoretically separated polypeptides transferred onto nitrocellulose, the peanut agglutinin (PNA) and MPA conjugates revealed upon neuraminidase treatment a broad Mr 140,000 polypeptide, compatible with podocalyxin, both in isolated developing and adult glomeruli. The MPA conjugate revealed a similar polypeptide in developing glomeruli, even without neuraminidase treatment. Similar experiments with the HPA and HAA conjugates revealed different polypeptides in both adult and developing glomeruli.Obviously, in the rat kidney the maturation of the podocyte sialoglycoprotein coat and the glomerular basement membranes are multiphasic processes that continue even during late postnatal development.
Ultrastructure of a model basement membrane lacking type IV collagen
Authors: Brauer Philip R. , Keller John M. 
Published: February 2005

AbstractBasement membranes (BMs) are specialized extracellular matrices which have important roles in cell attachment, migration, growth, and differentiation. The major components of these matrices include type IV collagen, laminin, entactin, and heparan sulfate proteoglycan. The framework or scaffold of BMs has been proposed to be type IV collagen (Yurchenco et al., 1986, J. Histochem. Cytochem., 34:93–102). However, a murine teratocarcinoma cell‐line, M1536‐B3, has been described which produces an extracellular matrix (ECM) composed of some of the known components of BM, e.g., laminin, entactin, and sulfated proteoglycan, but lacking type IV collagen (Chung et. al., 1979, Cell, 16:277–287). With the use of morphological techniques, we have found that the ECM assembled by these cells is composed of multiple layers of electron‐dense cords arranged in an interweaving meshwork with short 2–4 nm‐diameter cylindrical rods embedded throughout. This organization closely resembles that reported for naturally occurring BMs, e.g., Reichert's membrane (Inoué et al., 1983, J. Cell Biol., 97:1524–1537). The previous identification of known in vivo BM components in M1536‐B3 ECM and the correspondence in morphological appearance of M1536‐B3 ECM with that present in naturally occurring BMs suggests that a BM‐type of ECM can be assembled without a type IV collagen framework, thus indicating that other components of BMs have a critical role in BM organization and assembly.
Membrane relationships in murine meissner corpuscles: Cytology of freeze‐substituted tissue
Authors: Yoshida Yasuo , Ushiki Tatsuo , Takashio Minoru , Munger Bryce L. , Ide Chizuka 
Published: February 2005

AbstractMechanoreceptive sensory corpuscles (murine Meissner corpuscles) in the toe pad skin of mice, consisting of axon terminals and lamellar cells, were studied following freeze‐substitution in order to clarify the plasma membrane relationships between axon terminals and lamellar cells. Tissue preservation of corpuscles was excellent when the corpuscle was located within 10 μm from the contact surface with the precooled metal block.The axolemmata appeared more electron‐opaque than did plasma membranes of lamellar cells. The inner leaflet of the unit membranes was thicker than the outer leaflet in the axolemma, and the contour of cell plasma membranes was relatively smooth and straight. Characteristic focal or regional approximations of plasma membranes were noted between the axon and abutting lamellae. Such membrane appositions resembled gap junctions, although no gap junctions were found between the axon and lamellae in chemically fixed materials. Similar gap junction‐like close appositions of plasma membranes also were found between neighboring lamellae. These approximations occurred more frequently than typical gap junctions seen in chemically fixed materials. These findings indicate that there may be a relationship of the plasma membranes in the axon terminals and in abutting lamellae as well as between neighboring lamellae that have not been identified as yet in conventional chemically fixed material.Another striking finding was that basal laminae on lamellar cells exhibited the same electron opacity as the surrounding connective tissue matrix and thus the two are indistinguishable from one another. Furthermore, the lamina lucida was not evident, and basal lamina material was directly contiguous with the plasma membrane. These findings suggest that freeze‐substitution can retain materials that are easily extractable by conventional chemical fixation and dehydration.
Transfer of dorsoventral information from mesoderm to ectoderm at the onset of limb development
Authors: Geduspan Jane S. , Maccabe Jeffrey A. 
Published: February 2005

AbstractControl of dorsoventral patterns in the chick at the prelimb stages resides in the limb mesoderm. Recombination experiments at stage 14, with dorsoventrally reversed ectoderm, result in wings with mesodermal dorsoventral polarity. Similar recombinations at stage 16 show that the ectoderm has acquired dorsoventral information and can impose this polarity on the patterns of mesodermal differentiation in the distal regions of the wing. The dorsoventral information in the ectoderm comes from the mesoderm, which transfers this information to the overlying ectoderm between stages 14 and 16. The initial dorsoventral information in the ectoderm is not stable and can be reprogrammed by stage 14 mesoderm. Subsequently, there is a gradual stabilization of the ectodermal information. At the same time the mesoderm loses its capacity to reprogram dorsoventral information in the ectoderm.
Autonomic innervation of reproductive organs: Analysis of the neurons whose axons project in the main penile nerve in the pelvic plexus of the rat
Authors: Dail William G. , Trujillo Daniel , Rosa Diana De La , Walton Guy 
Published: February 2005

AbstractAn understanding of the composition of the various nerves of the pelvic plexus is essential in the design of studies to explore the autonomic control of pelvic visceral tissues. As a correlate of this interest, the present study was designed to determine the composition of the main penile nerve in the pelvic plexus of the laboratory rat, an animal commonly used for studies of reproductive physiology. Retrograde tracing studies indicate that the main penile nerve contains neurons which project to the penile crura, the corpus spongiosum, and the bulbourethral glands. The main penile nerve is the major source of neurons which innervate the corpus spongiosum and bulbourethral gland and contains about one‐third of all parasympathetic neurons which project to the penile crura. Dye placed on the proximal cut end of the main penile nerve indicates that neurons in the parasympathetic region of the spinal cord (L6‐S1) and to a lesser extent a sympathetic region of the cord, L1‐L2, provide preganglionic innervation to ganglion cells in the main pelvic nerve. Processes of neurons in dorsal root ganglia L6‐S1 and of neurons in the abdominopelvic sympathetic chain course in the main penile nerve to unknown destinations. In many respects this presumed postganglionic fiber tract is essentially a region of the pelvic plexus which subserves extrapelvic visceral tissues.
Rapid neuromuscular remodeling following limb immobilization
Authors: Fahim Mohamed A. 
Published: February 2005

AbstractThe effect of immobilization on endplate morphology of the rat soleus muscles was studied qualitatively and quantitatively. The endplate was visualized by light microscopic zinc iodide osmium (ZIO) staining and by electron microscopy. The soleus muscle was immobilized by pinning of ankle and knee joints at right angles for 5 days. Immobilized muscles were then compared to the contralateral side and to normal litter mates. After 5 days of partial disuse, muscle fibers atrophied and nerve terminal area increased in ZIO‐determined measurements. Neuromuscular junctions (NMJs) of disuse muscle fibers visualized by electron microscopy exhibited greater amounts of degeneration than either contralateral or control NMJs. Degeneration consisted of nerve terminal disruption, exposed junctional folds, and postsynaptic areas which contained little or no postjunctional folds. Regeneration also occurred in the same NMJs, consisting of small terminals associated with large expansion of junctional folds, several small terminals occurring within the same primary synaptic cleft, and several axons wrapped by the same Schwann cell. These observations demonstrate, for the first time, that partial disuse for only 5 days produces muscle atrophy as well as denervation‐like changes at the NMJ, which leads to terminal sprouting within the endplate area and remodelling.
Dentin matrix proteins: Composition and possible functions in calcification
Authors: Linde Anders 
Published: February 2005

AbstractDentin may be regarded as a mineralized connective tissue. In its composition as well as its mode of formation, dentin exhibits several similarities with bone, but also definite differences. The dentin organic phase, the matrix, determines its morphology and is believed to be instrumental in the formation of the mineral phase. A fibrous web of collagen type I dominates the organic matrix. Also, minor amounts of other collagen types may be present. The noncollagenous proteins (NCPs), which constitute about 10% of the matrix, fall into several categories: phosphoproteins, Gla‐proteins of the osteocalcin type as well as matrix Gla‐protein, proteoglycans, different acidic glycoproteins, and serum proteins. Some of these NCPs have unique chemical compositions that give them specific properties.Dentinogenesis occurs by two simultaneous processes: the formation of a collagenous web in predentin, which is followed by the formation of the inorganic phase at the mineralization front. The composition of the predentin organic matrix differs from that of dentin, as some NCP components are secreted extracellularly just in advance of the mineralization front. In addition, some constituents of predentin seem to be metabolized.The NCPs may be important to several processes during dentinogenesis. Much evidence indicates that noncollagenous components in the matrix are instrumental in mineral formation. New data show that polyanionic NCPs, such as phosphoprotein and proteoglycans, when immobilized on a solid support, induce apatite for‐mation under physiological conditions. These data indicate that polyanionic NCPs may function as mineral nucleators in vivo. They may also act as size and rate regulators for crystallization and promote calcium ion diffusion in the tissue. In addition, NCPs may regulate collagen fibrillogenesis.
Cartilage macromolecules and the calcification of cartilage matrix
Authors: Robin Poole A. , Matsui Y. , Hinek A. , Lee E. R. 
Published: February 2005

AbstractThe calcification of cartilage matrix in endochondral bone formation occurs in an extracellular matrix composed of fibrils of type II collagen with which type X collagen is closely associated. Also present within this matrix are the large proteoglycans containing chondroitin sulfate which aggregate with hyaluronic acid. In addition, the matrix contains matrix vesicles containing alkaline phosphatase. There is probably a concentration of calcium as a result of its binding to the many chondroitin sulfate chains. At the time of calcification, these proteoglycans become focally concentrated in sites where mineral is deposited. This would result in an even greater focal concentration of calcium. Release of inorganic phosphate, as a result of the activity of alkaline phosphatase, can lead to the displacement of proteoglycan bound calcium and its precipitation. The C‐propeptide of type II collagen becomes concentrated in the mineralizing sites, prior to which it is mainly associated with type II collagen fibrils and is present in dilated cisternae of the enlarged hypertrophic chondrocytes. The synthesis of type II collagen and the C‐propeptide, together with alkaline phosphatase, are regulated by the vitamin D metabolites 24,25(OH)2 cholecalciferol and 1,25 (OH)2 cholecalciferol. At the time of calcification, type X collagen remains associated with type II collagen fibrils. It may play a role in preventing the initial calcification of these fibrils focusing mineral formation in focal interfibrillar sites. This process of calcification is clearly very complex, and involves different interacting matrix molecules and is carefully regulated at the cellular level.
Biosynthesis and secretion of enamel proteins in the rat incisor
Authors: Nanci Antonio , Ahluwalia Jatinder P. , Pompura Julia R. , Smith Charles E. 
Published: February 2005

AbstractThe synthesis and secretion of enamel proteins (EPs) in rat incisors was examined using cytochemical and biochemical methods. Radioautography after injection of 3H‐methionine showed that ameloblasts in the presecretory, secretory, and maturation stages of amelogenesis actively synthesized and secreted proteins. Immunocytochemistry with an antibody to mouse amelogenins revealed the presence of EPs in the protein synthetic and secretory organelles of thesecellsatallthreestages. Labelingwasalsofoundinelementsoftheendosomal/lysosmal compartment. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and silver staining of proteins extracted from enamel and enamel organ showed several protein bands. However, transfer to nitrocellulose paper and immunoblotting revealed that most of the proteins recognized by the antibody were situated between approximately 14 and 32 kDa. EPs were further characterized by using lectins to examine their carbohydrate content. Lectin‐gold cytochemistry on sections showed the binding of wheat germ agglutinin and Helix pomatia lectin to secretory stage enamel. Lectin blotting indicated that the amelogenins were heterogeneously glycosylated and contained the sugars N‐acetyl‐glucosamine/N‐acetyl‐neuraminic acid and N‐acetyl‐D‐galactosamine. Fluorography at 6 and 10 min and 1 h after injection of 35S‐methionine revealed four labeled bands in the main amelogenin group near 22, 28, 30, and 32 kDa. A short‐lived protein of approximately 58 kDa was also observed primarily in cells. The appearance of labeled proteins in enamel was paralleled by their disappearance from cells and the intensity of the radiolabeled protein bands, both in enamel and in cells, decreased towards the maturation stage. These data are consistent with the concept that ameloblasts produce multiple amelogenins throughout amelogenesis.
Molecular mechanisms of bone resorption by the osteoclast
Authors: Baron Roland 
Published: February 2005

AbstractThe osteoclast is a multinucleated cell that is actively engaged in the synthesis of lysosomal enzymes, their vectorial transport toward the apical membrane, and the secretion of these enzymes at its apical pole. These secreted enzymes are targeted to the apical ruffled‐border membrane by mechanisms that involve cation‐independent mannose‐6‐phosphate receptors. These receptors bind to an enzyme‐linked mannose‐6‐phosphate recognition marker in the Golgi complex, and the enzyme‐ligand‐receptor complex, carried within small coated transport vesicles, dissociates upon reaching the low pH established in the bone‐resorbing compartment by the osteoclast. The apical bone‐resorbing compartment is sealed off by the attachment of the osteoclast to the calcified matrix and is actively acidified by the osteoclast. The plasma membrane of the cell is divided into distinct domains. The apical membrane at the ruffled‐border shares common antigenic determinants with lysosomal and endosomal membranes, including a 100 kD protein and proton pumps that may be involved in the acidification of the extracellular resorbing compartment. The basolateral membrane is highly enriched in sodium pumps. Finally, the cytoplasm of the osteoclast is highly enriched in carbonic anhydrase, and bicarbonate‐chloride exchange appears to regulate the intracellular pH of this cell. These observations are consistent with a scheme in which, in the low pH environment of the bone‐resorbing lacuna produced by the osteoclast, the mineral phase dissolves, exposing the organic matrix to the action of the secreted enzymes. The activity of these enzymes is in turn presumably favored by the acidic milieu. All constituents of the matrix, whether mineral or organic, then would be reduced to their elemental forms (ions and amino acids) extracellularly. No phagocytic events would be required for the complete degradation of the bone matrix. According to these concepts, therefore, membrane iontransport mechanisms become the most important molecular aspect of bone resorption.
Technique for reconstituting fixed cadaveric tissue
Authors: Blaney Sean P. A. , Johnson Barry 
Published: February 2005

AbstractDissecting room cadavers used over a prolonged period inevitably become desiccated, especially in well‐ventilated surroundings. It is particularly desirable that dissections used for end‐of‐year examinations be restored to their original condition. We describe here a quich and simple procedure designed to restore neglected specimens to their former condition at dissection. Specimens were either soaked for 24 hr in a standard solution of fabric conditioner or sprayed with the same standard solution. The specimens were then wrapped with muslin soaked in the conditioner and covered with polythene sheeting for 1 week. The results obtained were excellent and much superior to a short soak in water. The results further indicate that this technique may have other applications in the preparation of fixed histological material.
Effects of cholecystokinin and carbamylcholine on paneth cell secretion in mice: A comparison with pancreatic acinar cells
Authors: Satoh Yohichi , Ishikawa Katsushi , Oomori Yukio , Yamano Miki , Ono Kazuyuki 
Published: February 2005

AbstractTo confirm whether the Paneth cells of mice (ICR, male, 10–12 weeks old) have the same secretory response to hormonal and cholinergic stimulation as do pancreatic acinar cells, ultrastructural changes of Paneth cells and pancreatic acinar cells 1 hr after administration of various doses of cholecystokinin (octapeptide, CCK‐8) and carbamylcholine were morphometrically assessed. After maximal (1.5 μg/kg intraperitoneally [i.p.]) and supramaximal (15 μg/kg, i.p.) stimulation by CCK‐8, pancreatic acinar cells showed, respectively, degranulation or disturbance of secretion (e.g., an increase in lysosome‐like bodies, aggregation of zymogen granules). The Paneth cells, however, were almost unchanged in the parameters examined. After carbamylcholine injection (1,000 μg/kg, subcutaneously [s.c.]), both pancreatic acinar cells and Paneth cells showed degranulation. Paneth cells sometimes developed large vacuoles, probably formed after massive exocytosis; such vacuoles were not observed in pancreatic acinar cells. It is suggested that Paneth cells and pancreatic acinar cells have different secretory responses. Paneth cell secretion, which possibly plays a role in controlling the intestinal bacterial mileu, may be stimulated by cholinergic rather than hormonal mechanisms.