bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavior of chick primordial germ cells moving toward gonadal primordium in vitro: Scanning electron microscopic study
Authors: Kuwana Takashi , Miyayama Yukihiko , Kajiwara Yuji , Fujimoto Toyoaki 
Published: February 2005

AbstractPrimordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16‐mm time‐lapse filming or time‐lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed.With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: (1) The PGC produced a small pseudopodium. (2) This pseudopodium enlarged to the GR, and PGC‐substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. (3) Finally, the PGC as a whole moved toward the GR, being trailed by the process.The locomotion of the PGC on the thick collagen layer as a three‐dimensional substrate was as follows: (1) The PGC protruded a pseudopodium in the direction of the GR. (2) This pseudopodium elongated through the collagen network. (3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. (4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PGC in vivo.
Morphologic stages of the terminal hypertrophic chondrocyte of growth plate cartilage
Authors: Farnum Cornelia E. , Wilsman Norman J. 
Published: February 2005

AbstractRecent biochemical and morphologic evidence supports the concept that hypertrophic chondrocytes of growth plate cartilage are fully viable cells that play a major functional role in controlling endochondral ossification. However, events associated with chondrocyte death remain unknown. In this study we assess the viability of terminal hypertrophic chondrocytes in situ in an organ culture system viewed simultaneously with rectified Nomarski interference contrast optics and with vital staining under fluorescence optics. Second, we use two methods of optimal chemical fixation at the ultrastructural level to define morphologically distinct stages of the terminal hypertrophic chondrocyte, which we interpret as the stages preceding chondrocyte death. An analysis of serial sections at the light microscope level showed that terminal chondrocytes were found, with different probabilities, in three morphologically distinguishable stages. Seventy‐five percent of all profiles were fully hydrated cells with an intact plasma membrane making direct contact with the pericellular matrix, a morphology identical to that of living terminal chondrocytes viewed in Nomarski optics. Approximately 1% of terminal chondrocytes, while still in a fully hydrated state, consistently made a direct asymmetrical contact of the plasma membrane with the last transverse septum. In 24% of the profiles, terminal chondrocytes were found as condensed cells that retained their attachment to the last transverse septum. The stages were not characteristic of chondrocytes positioned more proximally in the growth plate. We hypothesize that a condensed morphology eventually characterizes each hypertrophic chondrocyte, and we relate these observations to current hypotheses concerning the mechanism of death of hypertrophic chondrocytes.
Paravascular cells in endosteal spaces of alveolar bone contribute to periodontal ligament cell populations
Authors: McCulloch C. A. G. , Nemeth E. , Lowenberg B. , Melcher A. H. 
Published: February 2005

AbstractEnddosteal spaces of alveolar bone communicate with the periodontal ligament and may contribute to its cell populations. We examined cell proliferation and migration in endosteal spaces and in the periodontal ligament contiguous with these spaces. Radioautographs of mouse mandibular molar were prepared from animals pulse‐injected with 3H‐Tdr and sacrificed in groups of 22 mice each at 1 h, 1, 3, and 7 d after labeling. Cell counts, labeling indices, grain counts, and progenitor cell ratios were determined. The data indicate that endosteal spaces are enriched with 3H‐Tdr‐labeled progenitor cells whose progeny rapidly migrate out of the compartment. The periodontal ligament contiguous with the endosteal spaces exhibited 5 times as many labeled cells as other sites in this tissue. Thickened areas of cementum were coincident with the openings of endosteal spaces in over 64% of observations. The data are consistent with the hypothesis that cells migrate from endosteal spaces into the periodontal ligament and there express the phenotype for osteoblasts or cementoblasts.
Embryonic development of the freshwater crayfish (Pacifastacus leniusculus Dana): A scanning electron microscopic study
Authors: Celada Jesús D. , de Paz Paulino , Gaudioso Vicente R. , Fernández Ramón 
Published: February 2005

AbstractThe egg development of the freshwater crayfish (Pacifastacus leniusculus Dana) under laboratory conditions is studied in this work from spawning to hatching. The sequence of its development is presented here, and the chronology of the different embryonic phases is established at one specific temperature (15.5°± 1°C).
The number of neurons in dorsal root ganglia L4–L6 of the rat
Authors: Schmalbruch Henning 
Published: February 2005

AbstractThe number of neurons in the dorsal root ganglia L4–L6 of the rat was determined because published data are inconsistent and in general incompatible with the number of afferent axons in the sciatic nerve. Nucleoli were counted in serial sections; epoxy‐resin sections 3 μm thick, or paraffin sections 5 μm thick, or unstained 12‐μm paraffin sections of osmicated tissue were used. Correction factors for split and multiple nucleoli were obtained by counting nucleolar profiles in consecutive sections of identified cells. Dividing the number of nucleolar profiles into the number of cells gave the factor by which the counts of nucleolar profiles had to be multiplied to obtain the number of neurons.The ganglia L4, L5, and L6 contained about 12,000, 15,000 and 14,000 neurons, respectively, when resin sections were used. The standard deviation for the average of 41,000 neurons in the three ganglia was 8% of the mean value. The results compare well with the number of dorsal root fibers, and with the fact that the sciatic nerve at midthigh, to which less than half of the neurons connect, contains 19,000 afferent axons. The data obtained from the paraffin series were 23% smaller, but still considerably higher and less variable than all previously reported data. The main problem with stained paraffin sections was that most small neurons had multiple nucleoli attached to the membrane of the nuclei, which only measured 10 μm in diameter. The nucleoli often projected into the dark cytoplasm and were difficult to identify.
Resident sinusoidal macrophages in the liver of the brown bullhead (Ictalurus nebulosus): An ultrastructural, functional and cytochemical study
Authors: Hampton James A. , Klaunig James E. , Goldblatt Peter J. 
Published: February 2005

AbstractUltrastructural, functional, and cytochemical characteristics of resident sinusoidal macrophages (RSM) in brown bullhead (Ictalurus nebulosus) liver were examined. Following perfusion fixation of the hepatic vascular bed, light micrographs revealed RSM that possessed multiple elongate cytoplasmic processes and frequently contained erythrocytes in various stages of degradation. Following brief perfusion fixation, light microscope examination of vibratome sections of bullhead liver reacted for peroxidase revealed intensely positive RSM. By transmission electron microscopy, peroxidase activity was localized to the nuclear envelope and cytoplasmic granules of RSM and in endothelial and perisinusoidal fat‐storing cells. In cryostat sections of fresh‐frozen liver, glucose‐6‐phosphate dehydrogenase (G‐6‐PDH) was uniformly distributed over hepatocytes, whereas intensely positive punctate staining for G‐6‐PDH was localized over RSM. To test for phagocytosis by RSM, latex beads (0.81 μ) were injected into a tributary of the hepatic portal vein 2 min prior to perfusion fixation. Latex beads appeared either singly or in dense aggregates within RSM. Ultrastructurally, RSM were characterized by an irregularly shaped, eccentrically located nucleus, electron‐dense vacuoles, small patches of granular endoplasmic reticulum, a well‐developed Golgi apparatus, elongated mitochondria, desmosomes or desmosome‐like densities that served as a source of attachment to endothelial cells, and a centriole with radiating microtubules. Invaginations of the plasma membrane (vermiform processes) characteristic of mammalian Kupffer cells were not observed in bullhead RSM. The results indicated a resident cell population of sinusoidal macrophages in the bullhead liver with properties that protially resembled mammalian Kupffer cells. These results are important for the identification of the normal resident cells in the bullhead liver.
Two types of secretory granules in gonadotrophs: Discrimination by the simultaneous EM immunocytochemical localization of serotonin and β‐follicle stimulating hormone
Authors: Payette Robert F. , Gershon Michael D. , Nunez Eladio A. 
Published: February 2005

AbstractThe hypothesis that the secretory granules of mammalian gonadotrophs are heterogeneous was tested. Previous studies had shown that all of the granules contain β‐luteinizing hormone (β‐LH) immunoreactivity, and some contain β‐follicle stimulating hormone (β‐FSH) or 5‐HT immunoreactivity. Moreover, differential release of β‐LH and β‐FSH has also been demonstrated. In the current study the pituitary glands of mice were investigated immunocytochemically at the ultrastructural level with antisera directed against human growth hormone (GH), β‐LH, β‐FSH, and 5‐HT. The immunoreactivities of β‐LH, β‐FSH, and 5‐HT were restricted to gonadotrophs. No 5‐HT immunoreactivity was seen in somatotrophs, identified by the immunoreactivity of GH in the secretory granules of these cells. Antisera to β‐LH labeled all gonadotroph granules; however, anti‐β‐FSH and anti‐5‐HT sera labeled only subsets of the granules. The proportion of granules labeled could not be increased by doubling the concentration of anti‐β‐FSH serum. The incidence of double labeling of granules by antisera to β‐FSH and 5‐HT was significantly less than that predicted from the incidence of granule labeling by either reagent alone. It is concluded that β‐FSH and 5‐HT immunoreactivities do not co‐exist in the same secretory granules of gonadotrophs; therefore, these granules are heterogeneous and there must be at least two types of granules. It is possible that the two types of granules may be responsive to different second messengers, thereby explaining the differential release of LH and FSH.
Neuromuscular junctions in adult and developing fast and slow muscles
Authors: Kwong W. H. , Gauthier Geraldine F. 
Published: February 2005

AbstractFunctional changes that occur just before hatching in future fast muscles of the chicken are thought to be influenced by the pattern of innervation. We have compared the neuromuscular junctions of two fast muscles, the posterior latissimus dors (PLD) and the pectoralis, which differ in their myosi composition at 18 days in ovo. We have also presented new information on the neuromuscular junctions of the adult fast muscles and an adult slow muscle, the anterior latissimus dorsi (ALD). Both categories of adult muscles were heterogeneous, and there was little difference between endplates of the two fast muscles or between the fast and slow muscles. In contrast, there were significant structural differences between the two fast muscles during embryonic development. In early embryonic muscle fibers, which synthesize embryonic forms of myosin, individual motor endplates were contacted by multiple axon terminals. At 18 days in ovo, the majority of the neuromuscular junctions in the pectoralis continued to be multiterminal, whereas all but one of the terminals had been withdrawn from each endplate in the PLD. This single terminal had a unique form that distinguished it from the embryonic pectoralis and also from the two adult muscles. By 7 days after hatching, the neuromuscular junctions of both muscles had single terminals. They were different from the embryonic terminals, through not necessarily equivalent to adult terminals. The results show that multiple terminals persist at 18 days in ovo in the muscle that continues to express an embryonic myosin, but they have been withdrawn from the muscle that has lost this myosin. It is concluded, from combined data on the two muscles, that maturation of the neuromuscular junction during embryonic and late posthatch development is correlated with transitions in the myosin pattern and in contractile properties.
Topography and behavior of Sertoli cells in sparse culture during the transitional remodeling phase
Authors: Tund Pierre S. , Choi Anthony H. C. , Fritz Irving B. 
Published: February 2005

AbstractWe report observations on the behavior of Sertoli cells in sparse culture during the period from the time of plating to the time of initial confluence (the transitional remodeling phase). Changes in shape, structure, and polarity of cells, as well as changes in migration patterns and cell‐cell association patterns, have been followed during the transitional remodeling phase with the aid of topographical markers. These markers are based upon differences between ultrastructural features of the basolateral and apicolateral surfaces. The basolateral surface is characterized by plasmalemmal blebs, whereas the apicolateral surface is characterized by filopodial extensions. Structural differences observed in sity remain evident in Sertoli cells isolated by sequential enzymatic treatments that are described. Another marker is provided by laminin‐binding sites, which are detected exclusively on the blebbed, basolateral surfaces of freshly prepared Sertoli cell aggregates. The orientation described is sustained during the initial radial migration of Sertoli cells explanted on uncoated glass coverslips. Under these conditions, blebs are detected only on the dorsal surfaces, and filopodial extensions are evident only on the ventral surfaces. In contrast, Sertoli cells sparsely plated on a reconstituted basement membrane (air‐dried Matrigel) migrate rapidly, display an extraordinary capacity to form elaborate cytoplasmic extensions for cell‐cell and cell‐substratum contracts, and readily retract blebs and filopodial extensions. These cells do not form mosaic borders, whereas cells plated on uncoated glass do form a monolayer with mosaic‐like borders. Cells sparsely seeded on gelated Matrigel migrate preferentially at gaps between adjacent cell explants, and develop a compact cell‐cell association pattern. These cells display few, if any, cytoplasmic extensions. We compare the behavior of Sertoli cells sparsely plated on Matrigel with the behavior of Sertoli cells in situ during different stages of development.
Dynamic changes in Sertoli cell processes invading spermatid cytoplasm during mouse spermiogenesis
Authors: Sakai Yasuhiro , Nakamoto Tadashi , Yamashina Shohei 
Published: February 2005

AbstractStudies using thick sections stained by ATPase cytochemistry and scanning electron microscopy were carried out to determine three‐dimensional ultrastructural alterations in Sertoli cell processes invading neighboring spermatids during mouse spermiogenesis. Sertoli cell processes start invading spermatid cytoplasm at the acrosomal phase of development and undergo considerable change at the maturation phase of development. At step 14, these processes elongate and begin to branch in the spermatid cytoplasm, and by step 15, they extend in various directions to form a complex of canals that the authors have designated the canal complex.The present observations also clarify that the complicated canal complex undergoes regional modification. At the late stages of maturation, the endoplasmic reticulum had gathered with other cell organelles to form aggregates of endoplasmic reticulum in the vicinity of which invading Sertoli cell processes extensively ramify further into thin tubules that intertwine with each other to form a region of thin tubules. In thin sections, each such region was a complex, consisting of small vesicles and endoplasmic reticulum, and corresponded to what has been defined as a mixed body by Morales and Clermont (Anat. Rec., 203:233–244, 1982). During the course of the formation of the region, the invading Sertoli cell processes are continuous at all times with the cell body of the surrounding Sertoli cell.
Basal lamina fenestrations in the human colon: Transmission and scanning electron microscope study
Authors: Warfel K. A. , Hull Meredith T. 
Published: February 2005

AbstractBasal lamina at the interface between colonic epithelial cells and the lamina propria was exposed by incubating colonic specimens in 1% boric acid solutions. Examination of this epithelial‐stromal interface by scanning electron microscopy (SEM) showed a smooth, slightly undulating basal lamina covering crypts and luminal surfaces. The basal lamina on the luminal surfaces had numerous round or ovoid fenestrations, most measuring 2.5–4.0 μm. These were continuous with channels in the collagen fiber network of the lamina propria. Except very near the surface, no fenestrations were found in the basal lamina lining the crypts. Transmission electron microscopy (TEM) of serial thin sections of colonic mucosa without the epithelial cells removed showed only a few actual basal lamina fenestrations. Rarely, epithelial cell processes extended into the lamina propria through the basal lamina. Most of the fenestrations seen by SEM appeared to correspond spatially by TEM to foci of close contact between the basal lamina and underlying fibroblastic cell processes. At these sites the basal lamina and fibroblastic cell process might be removed along with the overlying epithelial cells during processing with boric acid. These data support functional differences in epithelial‐stromal interaction between cell populations lining the luminal surface and those making up the crypt lining and pericryptal fibroblast sheath. The TEM findings demonstrate that the human colonic basal lamina is not absolutely continuous and that the development of basal lamina fenestrations and epithelial cell processes extending into the lamina propria is not pathognomonic of neoplastic transformation and stromal invasion.
Human lumbar zygapophyseal joint inferior recess synovial folds: A light microscope examination
Authors: Giles Lynton G. F. 
Published: February 2005

AbstractThe structure of human lumbar zygapophyseal joint inferior recess synovial folds as seen by high‐power light microscopy is described. Small paravascular nerves and nerves unrelated to blood vessels are demonstrated in the synovial folds. Elastic fibres are demonstrated in the interlocular fibrous septa of the synovial tissue.
Striped structures on the cytoplasmic surface membranes of the endothelial vesicles of the rat aorta revealed by quick‐freeze, deep‐etching replicas
Authors: Izumi Toshihiro , Shibata Yosaburo , Yamamoto Torao 
Published: February 2005

AbstractThe cytoplasmic surface of plasmalemmal vesicles in aortic endothelial cells was examined in quick‐freeze, deep‐etching replicas. In addition to the clathrin‐coated vesicles, striped patterns were observed over the cytoplasmic surface membranes of small vesicles (60–80 nm in diameter) in the unfixed specimens. These patterns were more clearly visible in saponin‐extracted specimens; the stripes were composed of several ridges or strands of 6–10 nm in width, and some were crossed. These were distinct from the characteristic pentagons or hexagons of the clathrin‐coated vesicles. This striped structure was enhanced by treatment with myosin subfragment‐1 or phalloidin, thereby indicating a possible relation to actin filaments. Patchy plaques with similar striped patterns appeared on the cytoplasmic surface of the plasmalemma proper and also on the cytoplasmic vacuole membranes together with clathrin. These striped structures may be involved in the formation and transport of so‐called “uncoated” vesicles.
Glial fibrillary acidic protein in chondrocytes of elastic cartilage in the human epiglottis: An immunohistochemical study with polyvalent and monoclonal antibodies
Authors: Kepes John J. , Perentes Elias 
Published: February 2005

AbstractGlial fibrillary acidic protein (GFAP), an intermediate filament, was first discovered in the cytoplasm of reactive astroglia and to this date is regarded as a rather characteristic component of both non‐neoplastic and neoplastic astrocytes. It has, however, been found in other glial elements also, as well as in a few types of tissues outside the central nervous system. Chondrocytes in hyaline and fibrocartilage do not express GFAP, but in the elastic cartilage of the human epiglottis we found GFAP to be regularly present when tested with either polyclonal or monoclonal antibodies. While most types of cartilage in humans are believed to be of mesenchymal origin, embryologic relationship between epiglottal cartilage and the neural crest may play a role in the curious phenomenon of the regular presence of GFAP in the chondrocytes of the epiglottis.
Characterization of proximal colonic lymphoid tissue in the mouse
Authors: Perry Greg A. , Sharp J. Graham 
Published: February 2005

AbstractHere were describe a nodule of lymphoid tissue which was consistently located in the proximal colon of mice approximately 25% of the distance from the cecum to the rectum. Immunohistochemical characterization of this nodule demonstrated that the majority of lymphocytes were relatively immature 14.8+ (B220+), IgM+, Ia+ (specificity 20) B cells some of which were also Ly‐1+. These nodules also possessed an occasional T cell (Thy‐1+, Ly‐1+, Lyt‐2+) aggregate at the periphery. Rare, small areas did not stain for either T or B cell markers. These lymphoid nodules were associated with epithelial cells which stained positively with the ER‐TR4 monoclonal antibody (which also recognizes thymic cortical epithelial cells) and also with ER‐TR6, which has been reported to recognize thymic macrophages or dendritic cells. The overlying colonic epithelium stained intensely with the ER‐TR4 monoclonal antibody. Proximal colonic lymphoid tissue was extremely sensitive to steroid treatment, losing approximately 80% of its mass within 24 hours in response to a single intraperitoneal injection of 2 mg hydrocortisone acetate. This response was similar to that of the thymus and to that reported for the bursa of Fabricius, but unlike that of other gastrointestinal lymphoid aggregates. These results indicated that proximal colonic lymphoid tissue contains a high frequency of relatively immature B cells and may be a primary site of their generation, possibly including some of the Ly‐1+ phenotype. These observations correlate with new evidence suggesting that the allantois participates in the formation of the distal midgut, including its lymphoid components.