bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gross morphological analysis of limb regeneration in postmetamorphic adult Ambystoma
Authors: Young Henry E. , Bailey Claudia F. , Dalley Bernell K. 
Published: February 2005

AbstractDue to the great disparity between regeneration times for the larval salamander (40 days), axolotl (30+ days), newt (44 days), and adult salamander (155 to 370 days), a staging system was devised so correlative comparisons could be made between regenerative model systems. The sequence was based on two criteria: (1) the stages should be similar to previously reported sequences for the newt, axolotl, and larval salamander, and (2) the stages must be readily recognizable by examination of the external morphology in the living state. Postmetamorphic adult land‐phase Ambystoma were amputated through the forearm, placed within survival conditions, and observed until regeneration was completed. Of the initial 160 salamanders, 157 (98%) progressed through 11 clearly defined stages of regeneration. A side‐by‐side comparison of the staging sequence for land and aquatic phase urodeles is given along with a summary of key external morphological characteristics for the adult salamander. It was noted that as the length of time for regeneration decreased, the relative ratio of the nerves innervating the limb (spinal nerves 4, 5, and 6) increased for the four species of Ambystoma examined: A. annulatum, 324 to 370 days postamputation (dpa) with a 1:1:1 neural tissue ratio; A. maculatum, 255 to 300 dpa with a 2:2:1 ratio; A. texanum, 215 to 250 dpa with a 2:2:2 ratio; and A. tigranum, 155 to 180 dpa with a 2:3:3 ratio.
Morphological evidence of the shedding of chondrocytes from the articular surface in neonatal rats: Relationship to the interlacunar network
Authors: Cole Madison B. , Narine Kamal R. , Ellinger Joan 
Published: February 2005

AbstractThe superficial zone of the femoral head articular cartilage of 5‐ to 15‐day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle ofthe zone appeared similar but with less cytoplasm. At the articular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: (1) Degenerating chondrocytes moved up through the superficial zone tothe articular surface and were shed into the joint space. This movement maybe facilitated by the network as part of neonatal cartilage development. (2) During joint formation, the surface of the articular cartilage was eroded down tothe chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar network.
The effect of osmium postfixation and uranyl and lead staining on the ultrastrucure of young enamel in the rat incisor
Authors: Nanci A. , Bai P. , Warshawsky H. 
Published: February 2005

AbstractEnamel crystallites are electron opaque without osmium or heavy metal staining and give a crystalline electron diffraction pattern. Since the opacity and diffraction pattern are abolished from ultrathin sections of young enamel by floating on distilled water (Bishop and Warshawsky, 1982), the possibility that aqueous staining may also remove crystallites was tested. In addition, the effect of osmium postifixation on crystallite structure was examined.Rat incisors fixed by perfusion with a mixture of aldehydes were either nonosmicated or osmicated prior to dehydration. Incisor segments in the region of inner enamel secretion were embedded in the same Epon block to ensure reliable comparison. Osmicated enamel was more intensely stained with toluidine blue and more electron opaque than nonosmicated enamel. No other structural differences were seen. However, crystallites in osmicated enamel were more resistant to grid demineralization and electron beam damage. Routine staining was done by floating sections on solutions of uranyl acetate and lead citrate; sections were also floated on similar solutions from which the heavy metals were omitted. These solutions removed the electron opaque crystallites from the youngest enamel. Stained sections showed electron opaque crystallite‐like structure similar to unstained enamel. When sections that were extracted by the solutions from which the metals were omitted were restained, they appeared identical to routinely stained enamel. It was conclud that staining of young enamel removes the crystallites and reveals only the organic matrix.
The liver hemopoietic environment: II. Peroxidase reactive mouse fetal liver hemopoietic cells
Authors: Medlock Eugene S. , Haar Jack L. 
Published: February 2005

AbstractThrough the combined use of peroxidase cytochemistry and examination at the ultrastructural level, the present study has identified liver hemopoietic foci containing three forms of erythropoietic cells, two forms of myelopoietic cells, and a population of peroxidase nonreactive cells within the extravascular compartments of mouse fetal liver. The nonreactive cells were 10 μm in diameter, displayed no peroxidase activity and were designated type I cells. This cell had an irregular nucleus, small profiles of rough endoplasmic reticulum (RER), a considerable population of monoribosomes and a few polyribosomes. The incidence of this cell type decreased significantly from 50% at 12 days gestation to approximately 10% of the hemopoietic cells at 17 days gestation. Type I cells could not be classified into a hemopoietic lineage and may represent undifferentiated hemopoietic stem cells. Three forms of erythropoietic cells, designated types II, III, and IV, were identified. These cells had a diffuse cytoplasmic peroxidase reaction, no peroxidase positive membrane‐bound organelles, and were approximately 7 μm in diameter. They corresponded to the more classically defined proerythroblast, polychromatophilic erythroblast, and nucleated normoblast, respectively. Types II and III had moderate cytoplasmic reactions, whereas type III, in addition, had a slight nuclear reaction. Type IV cells had a very dense cytoplasmic reaction but no nuclear reaction. Of the myelopoietic cells detected, one form had a slightly reactive Golgi and a few reactive granules. The other form possessed a clearly positive nuclear envelope (NE), RER, Golgi, and a population of reactive granules. The phagocytic sinusoidal lining cells (Kupffer cells) were peroxidase negative in contrast to similar cells in the rat. A population of peroxidasepositive granules was detected in fetal liver developing hepatocytes at 17 days gestation and increased in number with age. The morphology and organization of these various cell types in the liver hemopoietic environment are discussed.
Insulin‐ and glucagonlike peptides in the brain
Authors: Dorn A. , Bernstein H.‐G. , Rinne A. , Ziegler M. , Hahn H.‐J. , Ansorge S. 
Published: February 2005

AbstractThe cellular localization and regional distribution of insulin‐and glucagonlike substance, C‐peptide‐like immunoreactivity, thiol:protein disulphide oxidoreductase, TPO (E.C.1.8.4.2.), and insulin/glucagon‐specific proteinase, ISP (E.C.3.4.22.‐), are studied in the CNS of man, adult and juvenile rats, mice, tortoises, and frogs by use of immunohistochemistry. Furthermore, the content of immunoreactive insulin, glucagon, and C‐peptide was estimated in human cadaver brains by radioimmunoassay.It could be shown that insulinlike immunoreactive material is widely distributed in the human brain and the CNS of juvenile rats as well as in mice, whereas in the CNS of adult rats and nonmammalian animals (frog, tortoises) the polypeptide is restricted to a few nerve cell populations. C‐peptide immunoreactivity was demonstrated in human CNS in the same nerve cells as insulin.By use of two different glucagon‐antisera it was revealed that gut‐type glucagon occurs in many nerve cells of human and mouse brains, as well as in the CNS of juvenile rats. On the other hand, pancreas‐type glucagon was less widely distributed in the human brain and nearly not detectable in the CNS of mice and rats.With the exception of neurosecretory nerve cells, there was a high degree of coincidence between the localization of insulin and TPO. The immunoreaction against the ISP antiserum was weak, but correlated well with the distribution of insulin‐immunoreactivity.The occurrence of TPO and ISP in the brain demonstrates the ability of nervous tissue to degrade insulin and glucagon. By radioimmunoassay it was established that human brain contains insulin, glucagon and C‐peptide at concentrations that exceed blood levels.We conclude from our data that, at least in part, cerebral insulin and glucagon are products of the brain itself.
Effects of chronic denervation in type I cutaneous mechanoreceptors (Haarscheiben)
Authors: English Kathleen B. , Norman Dolores Kavka‐Van , Horch Kenneth 
Published: February 2005

AbstractCutaneous type I receptor sites (Haarscheiben or tactile domes) were examined at intervals of 4 to 275 days after chronic denervation of the skin. The number of domes decreased with denervation time, and only about one‐third of the domes originally present were still visible at 275 days. Most but not all of the Merkel cells from these domes were absent by 48 days, and the epithelium was significantly thinner than in nondenervated domes. Only a few of the examined domes appeared to be completely devoid of Merkel cells.It is concluded that after nerve transection, domes degenerate but do not always disappear entirely. The remmants may thus act as target sites which either attract regenerating type I nerve fibers or facilitate the formation of new dome structures after nerve regeneration.
Lymphatic and blood vessels of the popliteal node in sheep
Authors: Heath Trevor , Brandon Roslyn 
Published: February 2005

AbstractOur aim was to describe the lymphatic and blood vascular pathways to and from the popliteal lymph node in sheep. The blood vessels and lymphatics were filled with Microfil, and were cleared in methyl salicylate.Afferent lymphatics divide and anastomose as they pass dorsally along the lateral saphenous vein, and 6–12 lymphatics reach the node. Each branches extensively on the surface of the node giving rise to 20–50 terminal afferents which enter the node over a roughly circular area. Most enter the subcapsular sinus, but some penetrate deeply into the node. Lymph leaves the node through numerous initial efferent lymphatics, many of which contain valves. These join forming progressively larger vessels, and 2–4 efferent trunks emerge from the hilus.The hilus varies considerably in shape, depth and location, and it is filled with fat. Either a single artery, or up to 10–12 arteries derived from an anastomotic network or circle, enter the node from the hilar fat pad. Arteries may also enter at other sites. The arteries originate from the caudal femoral, or the medial circumflex femoral artery; a single node may receive blood from both arteries. This arrangement may help to maintain blood flow especially during an immune response, and despite external pressures applied to the arteries and node during movements of the animal.
Morphogenesis of motor endplates along the proximodistal axis of the mouse hindlimb
Authors: Carry Michael R. , Morita Michio , Nornes Howard O. 
Published: February 2005

AbstractThe morphogenesis of motor endplates along the proximodistal hindlimb axis is described for the mouse using nonspecific cholinesterase histochemistry and electron microscopy. There is a two day lag in relative stages of development between a proximal muscle (rectus femoris, RF) and a distal muscle (flexor hallucis brevis, FHB). Cholinesterase activity first appears in the RF on embryonic day 15 and the FHB on embryonic day 17. In the following days, faint wisps of reaction product thicken, form small ovals on myotubes, and finally enlarge with internal ramifications as the muscle fibers increase in diameter. Axons first enter the RF between embryonic days 12 and 13, and contact both embryonic cells (most likely myoblasts) and cells assumed to be Schwann cells. Myotubes are present in the RF the following day. The first signs of synapse formation—appearance of symmetrical electron opaque membrane patches, and dense cored and synaptic vesicles—occur between axons and myotubes in the RF on embryonic day 15. During the following days basal lamina material accumulates in the synaptic cleft, coated vesicles and postjunctional folds appear in the myotubes, and synaptic vesicles accumulate in the axon terminals. By postnatal day 42 the axon terminals lay in primary gutters opposite deep secondary postjunctional folds, and are separated and capped by Schwann cell processes.
Retention of generalized hair cell patterns in the inner ear of the primitive flatfish psettodes
Authors: Platt Christopher 
Published: February 2005

AbstractFlatfish are a group of uniquely asymmetrical vertebrates, lying always on one side. This postural control depends on the vestibular receptors of the inner ear. From the most primitive living flatfish, orientations of sensory hair cells in the inner ear were mapped by scanning electron microscopy. The maps of the three otolith organs, the three semicircular cristae, and the macula neglecta (newly discovered here for flatfish) show patterns that are very similar to those in many upright teleosts, particularly perches. Thus, peripheral sensory structure does not require modification for the unusual postural control of flatfish.
Innervation of the canine thoracolumbar vertebral column
Authors: Forsythe W. B. , Ghoshal N. G. 
Published: February 2005

AbstractThe pattern of innervation of the caudal thoracic and cranial lumbar vertebral column of the dog is described. Frozen sections stained with Schofield's silver impregnation method show that the dorsal longitudinal ligament is profusely innervated, while the anulus fibrosus contains a few nerves limited to its outermost layers; no nerves are present in the nucleus pulposus. Following injection of horseradish peroxidase (HRP) into the anulus fibrosus of the thoracolumbar intervertebral disc and subsequent removal and staining of dorsal root ganglia, the reaction product is found in ganglia as far as two segments cranially as well as caudally, demonstrating that the disc is innervated by nerves arising from several spinal cord segments. A meningeal ramus, which innervates the discs of man, could not be found by gross dissection. Dissections show each vertebral articular facet innervated by the medial branches of two contiguous spinal nerves, a pattern further confirmed by injections of HRP into facet joints with subsequent staining of dorsal root ganglia. The dorsal rami of spinal nerves often divide into medial, intermediate, and lateral branches rather than the traditionally described division into only medial and lateral branches.
Development of macrophages in the lungs of fetal rabbits, rats, and hamsters
Authors: Sorokin Sergei P. , Hoyt Richard F. , Grant Margaret M. 
Published: February 2005

AbstractFetal rabbits (days 13–32), rats (days 14–22), and hamsters (days 11–15) and selected postnatal animals were examined for pulmonary macrophages or their precursors in 2‐m̈m sections stained by PAS‐lead hematoxylin (all species), electron micrographs (rabbit and rat), and cytochemical incubations for acid phosphatase (rabbit and rat), aliesterase, and N‐acetyl glucosaminidase (rabbits). All methods revealed macrophages in perinatal specimens. The appearance and distribution of these cells were compared in the different preparations to establish the reliability of PAS‐lead hematoxylin for identifying them in less developed fetal lungs, where they are less active for lysosomal enzymes the earlier the stage examined. In the sections, macrophages are seen to possess a round or indented nucleus, an irregular contour, and a deep purplish‐gray cytoplasm containing a variety of pink PAS‐stained granules, equated with heterolysosomes by ultrastructural cytochemistry. In less developed lungs, macrophages occur along with putative precursors having a more rounded outline and fewer PAS‐stained granules. In pseudoglandular lungs these precursors predominate over rather vacuolated macrophages resembling Hofbauer cells. In all three species both cell types first appear in the stroma during the bronchial bud stage and are frequently seen to divide from that time on. The earliest precursors have a relatively sparse cytoplasm which later increases in daughter cells. Hofbauer‐like cells disappear during the canalicular stage of development, replaced by macrophages and transitional forms from the more rounded precursors. In day 21 rabbit lungs, scattered stromal cells are reactive for aliesterase, and, some days later, for acid phosphatase and glucosaminidase. Free mononuclear cells are rare in airways of pseudoglandular lungs but become common later. A day or two before birth in rats, free cells range between rather undifferentiated leukocytes to typical macrophages, but cells with the macrophage's complete repertory of inclusions are seen only after birth. In the fetus, typical monocytes were not identified in either the pulmonary stroma or the airways. A replicating population of macrophage‐like cells therefore resides in fetal lungs. It is established before bone marrow is formed and, in rats, before monocytes have appeared in the circulation.
The mechanisms of cell death and phagocytosis in the early chick lens morphogenesis: A scanning electron microscopy and cytochemical approach
Authors: Garcí‐Porrero Juan A. , Colvée Elvira , Ojeda José L. 
Published: February 2005

AbstractThe cell surface characteristics of degenerating cells and phagocytes, as well as the participation of lysosomes in the cell death process associated with the early embryogenesis of chick lens rudiment, were studied by means of scanning electron microscopy and cytochemically using the Gomori‐b̃‐glycerophosphate method for acid phosphatase.The prospective dying columnar epithelial cells lose their apical and basal processes and become rounded. The rounded, isolated, dying cells initially show a rough surface with some cytoplasmic constrictions followed by progressive break‐up into several pitted fragments. Coincident with the loss of the columnar cell shape, acid phosphatase is localized within the Golgi apparatus and autophagic vacuoles which progressively increase in size. In contrast, the isolated dying cells and fragments do not show significant acid phosphatase activity. The role of lysosomes in this degenerative process is discussed.Neighboring epithelial cells phagocytose the dead cell fragments, becoming nonspecialized phagocytes. These consist of columnar epithelial cells and free cells which have migrated from the lens epithelium. Two mechanisms of internalization are observed. The most frequent mechanism takes place in both the columnar epithelial cells and the free cells, and consists of the progressive engulfment of the fragments into craters of the cell surface. The other mechanism is only detected in the free cells and takes place by pseudopod engulfment. We suggest that both phagocytic procedures could be related to the degree of intercellular connection. The presence of phagocytic internalization by crater formation in the epithelial cells could be a mechanism preserving the epithelial stability, which is necessary for a normal morphogenesis. Small microprocesses binding the surface of the phagocyte and the fragment are present prior to the internalization process.In the lens stalk and in the space located between the ectoderm and the lens vesicle, there are some cells displaying migratory characteristics. This fact suggests that an active migration of epithelial cells from the lens stalk could account for the process of detachment of lens vesicle from the ectoderm. The free cells appear to undergo an in situ progressive degeneration.
Binding of secreted glycoproteins to spermatozoa in the mammalian epididymis: A fine‐structure autoradiographic study
Authors: Kopečný V. , Fléchon J.‐E. , Pivko J. 
Published: February 2005

AbstractMouse and guinea pig epididymal tissues have been investigated by light and electron microscopic autoradiography after long intervals ranging from 24 h to 5 days postinjection (p.i.) of the glycoprotein precursors, L‐fucose‐6‐3H of D‐glucosamine‐1‐3H. Using modified fixations to enhance glcoprotein preservation in situ, we found intense labelling of luminal contents in at least some of the epididymal segments after all the intervals investigated. At 24 h p.i., the label in guinea pig was associated with spermatozoa during remodelling of the acrosome in segment II, and at 3 days p.i., radioactivity was trapped within sperm head associations (“rouleaux”) in segment IV of the epididymis. At this time, similar rouleau labelling extended from segment IV to segment VIII. In mouse, the luminal contents of the cauda epididymis were still intensely labelled at 5 days p.i.; analysis of the electron microscopic autoradiograms showed that relative grain concentration over the spermatozoa was twice that of the epididymal plasma. This concentration was especially elevated in the region of the sperm head. These findings taken together were interpreted as the binding of secreted epididymal glycoproteins to spermatozoa during sperm transit through the epididymis.In contrast to luminal contents, the labelling of the epididymal epithelium was generally lower, except on the clear cells which showed more pronounced labelling than the neighboring principal cells in mouse cauda epididymis at 5 days p.i. This label probably originated from the resorption of luminal glycoproteins.
Identification system for airways in lung models: A note
Authors: Patra Amit L. , Grady Margaret A. , Miller Frederick J. 
Published: February 2005

AbstractA lobar notational system for the identification of airways in the mammalian lung is presented. This system was developed to identify uniquely the location of morphometric and deposition data within a lobe as well as within the lung, and to provide for easy and efficient data reduction. In addition, this notational system can be used to identify main stems like those found in the monopodial lung, and incorporates identification of terminal bronchioles in the airway identifier. The lobar notational system is composed of a two‐character lobe code, followed by a third character identifying the branching structure as monopodial or symmetric. The fourth digit identifies the relative position of a branch within the lobe. Subsequent digits identify the airway's relative location within the branching.