bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accessory cells in the gill epithelium of the freshwater rainbow trout Salmo gairdneri
Authors: Pisam M. , Prunet P. , Rambourg A. 
Published: February 2005

AbstractTwo types of mitochondria‐rich cells were identified in the gill epithelium of the freshwater‐adapted rainbow trout, Salmo gairdneri, after selective impregnation of their tubular system with reduced osmium. A first type consisted of large cells with a poorly developed and loosely anastomosed tubular system; thus, that resembled the chloride cells commonly encountered in the gill epithelium of freshwater‐adapted euryhaline fishes. A second type comprised smaller cells with an extensively developed and tightly anastomosed tubular system. These never reached the basal lamina of the gill epithelium and were adjacent to chloride cells, to which they were linked by shallow apical junctions (100‐200 nm); thus, they resembled accessory cells, which are currently found in the gill epithelium of sea‐water‐adapted fishes but are usually lacking in freshwater living fishes. Transfer of the freshwater‐adapted trout into seawater induced the proliferation of the tubular system in the chloride cells and the formation of lateral plasma membrane interdigitations between accessory cells and the apical portion of the chloride cells. The length of the apical junction sealing off this ex tended intercellular space was reduced to 20‐50 nm. The tubular system of the accessory cells was not modified. The extension of the tubular system in the chloride cells of the seawater‐adapted fishes indicated that, as in most euryhaline fishes, these cells have a role in the adaptation of the rainbow trout to seawater. In contrast, the function of the presumptive accessory cells in fresh water trout remains to be established.
Colonization of the developing pancreas by neural precursors from the bowel
Authors: Kirchgessner A. L. , Adlersberg M. A. , Gershon M. D. 
Published: February 2005

AbstractNeurons in ganglia of the myenteric plexus of the duodenum and stomach have recently been demonstrated to innervate pancreatic ganglia and transsynaptically to excite acinar and islet cells. The hypothesis that crestderived cells first colonize the foregut and secondarily enter the pancreas by way of the pancreatic buds was tested. Studies were done with fetal rats (days E11–E15). Pancreatic rudiments and foregut were explanted separately and in co‐culture. The development of neurons in the explants, identified by demonstrating the immunoreactivities of neurofilaments and growthassociated protein‐43 (GAP‐43), provided an indirect assay for the presence of neural precursors in the tissue at the time of explantation. Cells of putative neural crest origin were visualized immunocytochemically using the monoclonal antibody, NC‐1. Additional markers included the immunoreactivities of dopamine‐β‐hydroxylase (DBH), which is expressed by vagal crest‐derived cells that colonize the bowel, neuropeptides (substance P and neuropeptide Y [NPY]) found in mature pancreatic neurons, and serotonin (5‐HT), which is located in the cell bodies of enteric but not pancreatic neurons. Neurons were detected in cultures of foregut, but not pancreas, when these tissues were explanted by themselves at days E11 and E12. At E11 neural precursors did not leave explants of bowel or migrate into co‐cultured pancreatic rudiments. When the foregut was explanted at E12, however, neural precursors migrated away from the bowel, giving rise both to distant ganglia and to neurons within co‐cultured pancreatic rudiments. Intrapancreatic ganglia developed in the co‐cultures even when the pancreatic attachment to the bowel was severed. Neurons appeared in pancreatic rudiments explanted by themselves on day E13. Neurons developing in pancreatic explants expressed the immunoreactivities of DBH, substance P, and NPY, but not 5‐HT. These observations support the idea that pancreatic ganglia develop from crest‐derived cells that first colonize the fetal rat foregut and there acquire the ability to colonize the pancreas. A later migration into the pancreatic rudiments of a subset of the original émigrés or their progeny between days E12 and E13 gives rise to a network of pancreatic ganglia that can be regarded as an extension of the enteric nervous system. © 1992 Wiley‐Liss, Inc.
EMA: A developmentally regulated cell‐surface glycoprotein of CNS neurons that is concentrated at the leading edge of growth cones
Authors: Baumrind Nikki L. , Parkinson David , Wayne Denise B. , Heuser John E. , Pearlman Alan L. 
Published: February 2005

AbstractTo identify cell‐surface molecules that mediate interactions between neurons and their environment during neural development, we used monoclonal antibody techniques to define a developmentally regulated antigen in the central nervous system of the mouse. The antibody we produced (2A1) immunolabels cells throughout the central nervous system; we analyzed its distribution in the developing cerebral cortex, where it is expressed on cells very soon after they complete mitosis and leave the periventricular proliferative zone. Expression continues into adult life. The antibody also labels the epithelium of the choroid plexus and the renal proximal tubules, but does not label neurons of the peripheral nervous system in the dorsal root ganglia. In dissociated cell culture of embryonic cerebral cortex, 2A1 labels the surface of neurons but not glia. Immunolabeling of neurons in tissue culture is particularly prominent on the edge of growth cones, including filopodia and the leading edge of lamellipodia, when observed with either immunofluorescence or freeze‐etch immunoelectron microscopy. Immunopurification with 2A1 of a CHAPS‐extracted membrane preparation from brains of neonatal mice produces a broad (32–36 kD) electrophoretic band and a less prominent 70 kD band that are sensitive to N‐glycosidase but not endoglycosidase H. Thus the 2A1 antibody recognizes a developmentally regulated, neuronal cell surface glycoprotein (or glycoproteins) with complex N‐linked oligosaccharide side chains. We have termed the glycoprotein antigen EMA because of its prominence on the edge membrane of growth cones. EMA is similar to the M6 antigen (Lagenaur et al: J. Neurobiol. 23:71–88, 1992) in apparent molecular weight, distribution in tissue sections, and immunoreactivity on Western blots, suggesting that the two antigens are similar or identical. Expression of EMA is a very early manifestation of neuronal differentiation; its distribution on growth cones suggests a role in mediating the interactions between growth cones and the external cues that guide them. © 1992 Wiley‐Liss, Inc.
Expression of Hox 2.1 protein in restricted populations of neural crest cells and pharyngeal ectoderm
Authors: Kuratani Shigeru C. , Wall Nancy A. 
Published: February 2005

AbstractA polyclonal antibody, αHox 2.1a, was used to localize Hox 2.1 protein in presumptive neural crest cells and nodose ganglion of 8.5–10.0 day p.c. mouse embryos. The following results were obtained: (1) The nodose placode, in its epithelial state, first expresses Hox 2.1 protein at 9.0 d.p.c. By 9.5 d.p.c. presumptive migrating neuroblasts between the nodose placode and ganglion primordium also express Hox 2.1 protein. (2) At 9.5 d.p.c., presumptive crest cells lateral to the cephalic cardinal vein and within pharyngeal arches 4 and 6 are immunoreactive for αHox 2.1a. In the arch 6 region, positive cells extend medially to a mesenchymal cell population on the lateral aspect of the foregut wall. (3) At 10.0 d.p.c., Hox 2.1 protein expression in putative crest cells is restricted to the arch 6 cell population. A similar staining pattern is seen using αHox 2.1a with chick embryos. Comparison with the chicken embryo suggests that the Hox 2.1 positive cells in the pharyngeal arch and those on the lateral aspect of the foregut in the mouse embryo correspond to the caudalmost subpopulation of the circumpharyngeal crest (Kuratani and Kirby: Dev. Dyn. 191:215–227, 1991; Anat. Rec. 234:263–280, 1992). These results are consistent with a role for Hox 2.1 in pattern formation in the caudalmost region of the vertebrate head. © 1992 Wiley‐Liss, Inc.
The zonal expression of α‐fetoprotein transgenes in the livers of adult mice
Authors: Emerson Julia Andrew , Vacher Jean , Cirillo Lisa Ann , Tilghman Shirley M. , Tyner Angela L. 
Published: February 2005

AbstractThe developmental regulation of the α‐fetoprotein (AFP) gene in liver results in high‐level expression in the fetus, followed by dramatic transcriptional repression after birth. We have examined the mouse AFP gene for transcriptional control sequences that may be involved in its postnatal repression in liver. We showed previously that removal of a DNA region between positions −250 base pairs (bp) and −838 bp of the AFP gene resulted in the persistence of expression of an AFP minigene in the postpartum liver of transgenic mice (Vacher and Tilghman, Science 250:1732–1735, 1990). This study examines the distribution of these transgene transcripts in liver using in situ hybridization. We show that there is a zonal distribution of minigene transcripts in the adult livers of these animals. Hepatocytes surrounding the central veins express high levels of minigene transcripts, while hepatocytes in the intermediate and portal areas contain few, if any, transcripts. Quantitative RNAse protection analysis shows a decrease in transgene RNA levels after birth, consistent with repression in all but a small subset of hepatocytes. These results indicate that repression in the pericentral hepatocytes is dependent upon the presence of a cis‐acting, negative‐regulatory domain, which is located between the enhancers and the proximal promoter of the AFP gene. In contrast, this domain is not essential for complete repression of AFP transgenes in the intermediate zone and periportal hepatocytes. © 1992 Wiley‐Liss, Inc.
Coordinate expression of IGF‐I and its receptor during limb outgrowth
Authors: Geduspan J. S. , Padanilam B. J. , Solursh M. 
Published: February 2005

AbstractThe morphogenetic mechanisms involved in shaping the embryo are largely unknown. Previous studies from this laboratory suggest that the mesonephros promotes limb outgrowth in ovo in the chicken embryo and might be involved in early limb morphogenesis, since damage to the mesonephros results in truncated limbs. In limb bud organ cultures, the presence of the mesonephros promotes cartilage formation. This effect can be reproduced by exogenous IGF‐I or prevented by blocking antibody to IGF‐I. In order to examine the hypothesis that mesonephros‐derived IGF‐I is involved in the early morphogenesis of the limb, we examined the spatial and temporal expression of IGF‐I and type I receptor for IGF by in situ hybridization at stages when the onset of limb development occurs. The results show that neither transcript is detected at stage 13, prior to the appearance of the limb bud; but both transcripts are detected in the mesonephros at stage 14, an early stage in limb outgrowth. The hybridization signal in the mesonephros for both transcripts increases with development and signal was codistributed as well. At stage 18 the level of receptor transcripts detected in the flank relative to the limb decreased. Thus, the temporal and spatial patterns of expression of IGF‐I and its receptor are consistent with their involvement in the initiation of limb outgrowth and support the model that localized expression of a growth factor and its receptor can be involved in shaping the embryo. © 1992 Wiley‐Liss, Inc.
Localization of pro‐α2(V) collagen transcripts in the tissues of the developing mouse embryo
Authors: Andrikopoulos Konstantinos , Suzuki Hiroaki R. , Solursh Michael , Ramirez Francesco 
Published: February 2005

AbstractCorrect assembly of fibrillar collagen networks plays a critical role in animal morphogenesis. Very little is known about the contribution of the so‐called minor fibrillar collagens (types V and XI) to fibrillogenesis. Here we examined the developmental expression of the mouse pro‐α2(V) collagen gene (col5a2) after the cloning and sequencing of cDNAs that cover the entire length of the message. Transcripts of col5a2, detectable as early as 9 days of gestation, localize with distinct patterns in the tissues of day 12.5 and day 16.5 fetuses. The earlier developmental stage is characterized by low and diffuse col5a2 expression in the peritoneal membranes and intestinal and craniofacial mesenchymes. The later stage exhibits higher and more restricted col5a2 mRNA accumulation in primary ossified regions, perichondrium, joints, tendon, atrioventricular valve of the heart, and selected portions of the head. A parallel analysis using a cartilage‐specific pro‐α1(II) collagen (col2a1) probe confirmed that these two collagen genes are transcribed in a mutually exclusive manner during mouse embryogenesis. On the other hand, the developmental pattern of col5a2 expression closely resembles that of the type I collagen, thus further substantiating the notion that these macromolecules cooperate in the formation of fibrillar networks in non‐cartilaginous matrices. © 1992 Wiley‐Liss, Inc.
Localization of epidermal growth factor and its receptor in mandibular molars of the rat prior to and during prefunctional tooth eruption
Authors: Wise Gary E. , Lin Fan , Fan Wei 
Published: February 2005

AbstractImmunoperoxidase localization of epidermal growth factor receptors (EGFR) and epidermal growth factor (EGF) itself was examined in rat first and second mandibular molars postnatally from day 0 to 12. The results showed that the dental follicle stained heavily for EGFR from day 0 to 8, declined in staining at day 9, and was devoid of stain from day 10 onward. Preosteoblasts and osteoblasts of alveolar bone also stained and lesser staining of ameloblasts and odontoblasts was observed. Except for staining of occasional isolated cells, the stellate reticulum did not stain. Light staining of the dental pulp of the first mandibular molar was seen from day 0 onward but the pulp of the second molar did not stain until approximately day 6. With respect to EGF, the dental follicle also stained for it until day 12. The ameloblasts stained more intensely for EGF than for EGFR. Because injections of EGF cause premature eruption of teeth and because the presence of a dental follicle is necessary for eruption, this study suggests that EGF could have its effect on the follicle as seen by the presence of EGFR receptors on the follicle. Moreover, because EGF exerts its effects early (day 0–3) to cause eruption and because the influx of monocytes into the follicle to form osteoclasts for bone resorption for eruption occurs early, the heavy staining for EGFR in the follicle early followed by the absence of staining at day 10 correlates chronologically with the key molecular and cellular events of eruption. Finally, the presence of EGF in the follicle, as well as enamel organ, could provide an endogenous source of EGF to regulate tooth eruption, either by an autocrine or a paracrine effect. Thus, the localization of EGFR and EGF in the dental follicle coupled with the chronology of localization suggests that EGF could play a physiological role in tooth eruption. © 1992 Wiley‐Liss, Inc.
Comparison of Hensen's node and retinoic acid in secondary axis induction in the early chick embryo
Authors: Chen Yiping , Solursh Michael 
Published: February 2005

AbstractRetinoic acid (RA) and Hensen's node, the organizer center in the chick embryo, have been shown to have polarizing activity when applied or grafted into the chick limb bud. Here we investigate and compare the effects of RA and grafted Hensen's node on the early chick embryo. Anion exchange beads soaked with RA at concentrations ranging from 5 to 100 ng/ml and implanted on the anterior side or on the left side of the host anteroposterior axis of a stage 4 chick embryo in ovo have the ability to induce secondary axis formation, while beads soaked with RA of the same concentration and implanted on the right side or on the posterior side of the host axis are unable to induce the secondary axis. All of the induced axes contain trunk‐tail structures. Hensen's node from quail embryos implanted into the early chick blastoderm could also cause the formation of secondary axes in addition to self‐differentiation of the graft into a secondary axis. Both RA and grafted Hensen's node caused the inhibition of forebrain development with an increase in hindbrain development and the host heart to loop in an abnormal direction. The results support the hypothesis that Hensen's node is a source of RA which is involved in early embryo‐genesis. Alternatively, RA might stimulate the formation of Hensen's nodal properties in adjacent tissue. © 1992 Wiley‐Liss, Inc.
Cell interaction and its role in mesoderm cell migration during Xenopus gastrulation
Authors: Winklbauer Rudolf , Selchow Andreas , Nagel Martina , Angres Brigitte 
Published: February 2005

AbstractIn the Xenopus gastrula, the mesoderm moves as a coherent cell aggregate across the blastocoel roof toward the animal pole. We show that the cohesion of the mesoderm is not only mechanically necessary, but that aggregate formation has profound effects on the migratory behavior of mesoderm cells. Whereas isolated mesoderm cells are bi‐ or multipolar, move stepwise and change their direction of movement frequently, aggregated mesoderm cells migrating on their in vivo substrate appear unipolar and move continuously and persistently. Moreover, only mesoderm cell aggregates, but not single cells, can follow guidance cues present in the extracellular matrix of the blastocoel roof substrate. Thus, the cohesion of the mesodermal cell mass is an essential feature of mesoderm migration during Xenopus gastrulation. We show that the Ca2+‐dependent cell adhesion molecule U‐cadherin is involved in mediating this cohesion. © 1993 Wiley‐Liss, Inc.
Growth pressure can drive early chick lens geometries
Authors: Hendrix Richard , Madras Neal , Johnson Robert 
Published: February 2005

AbstractOver a number of morphological stages during chick lens morphogenesis, a flat plate of cuboidal ectodermal cells infolds to form a deep cup of tall, pyramidal lenticular cells. This invagination process is accompanied by asynchronous cellular multiplication over a basal region constrained by an adhesive extracellular matrix. A lens placode is formed as the cells crowd into columnar ‘palisades.’ A lens cup forms as the cells pyramidalize owing to basal nuclear movements. Invagination ends when the opening into the lens cup is closed to form a lens vesicle. In this paper, equations are developed that provide a quantitative, mathematical formulation of an earlier theory that explains this invagination as a growth driven process. The equations take into account the lens cell cycle, the extracellular matrix, and nuclear migratory behaviors. Based on the equations, geometries simulating the morphological stages and the cell cycle phases are generated for the 1st day of lens development. The mathematical formulation of lens invagination helps demonstrate how growth pressure alone can be the primary driving force for tissue folding. In this view, recruitment occurs before the shape changes; and cell‐autonomous mechanisms of invagination, involving the cytoskeleton or differential adhesion alone, offer inadequate explanations of these changes. © 1993 wiley‐Liss, Inc.
Ectopic expression of MyoD1 in mice causes prenatal lethalities
Authors: Faerman Alexander , Pearson‐White Sonia , Emerson Charles , Shani Moshe 
Published: February 2005

AbstractA variety of differentiated cell types can be converted to skeletal muscle following transfection with the myogenic regulatory gene MyoD1. To determine whether MyoD1 is a dominant muscle regulator in vivo, mouse fertilized eggs were microinjected with a β‐actin/MyoD1 gene. Ectopic expression of MyoD1 during mouse embryogenesis led to embryonic lethalities, the cause of which is not known. Transgenic embryos died before midgestation. The majority of tested embryos between 7.5 and 9.5 days, although retarded compared to control littermates, differentiated normally into tissues representative of all three germ layers. In most transgenic embryos there was no indication of myogenic conversion. The expression of the introduced gene was detected in all ectodermal and mesodermal tissues but was absent in all endodermal cells. Forced expression of MyoD1 was associated with the activation of myogenin and MLC2 (but not myf5 or MRF4) genes in non‐muscle cell types, demonstrating the dominant regulatory function of MyoD1 during development. These results demonstrate that ectopic MyoD1 expression and activation of myogenin and MLC2 have no significant effects in the determination of cell lineages or the developmental fate of differentiated mesodermal and ectodermal cell lineages. © 1993 wiley‐Liss, Inc.
Expression of N‐cadherin mRNA during development of the mouse brain
Authors: Redies C. , Takeichi M. 
Published: February 2005

AbstractThe expression of N‐cadherin mRNA was mapped in the brain of mice between embryonic day 12 (E12) and the adult stage by in situ hybridization of digoxigenin‐labeled riboprobe. Two phases of N‐cadherin expression can be distinguished. During the first phase (about E12 to E16), expression is ubiquitous throughout the brain and most prominent in the proliferative neuroepithelium. During the second phase (about E16 to postnatal day 6), N‐cadherin expression is restricted to particular nuclei or laminae that share common functional features and neuroanatomical connections. Several of the N cadherin‐positive structures receive direct afferents from retinal ganglion cells or from the superior colliculus. Others belong to the reticular system and to the limbic system of the brain. In neocortex, N‐cadherin is expressed by deeper layer cells. In the adult brain, only low levels of N‐cadherin expression remain in very few types of cells, for example in the Purkinje cells of the cerebellum.These results are similar to data from chicken brain and suggest that the generalized expression of N‐cadherin during the early phase and the restriction expression of this molecule in particular functional systems during the later phase is, at least in part, phylogenetically conserved between chicken and mouse. Moreover, the results show that N‐cadherin expression extends to phylogenetically newer structures, e.g., the mammalian neocortex. © 1993 Wiley‐Liss, Inc.