bluuebunny/crossref_metadata_2025_split huggingface dataset:
α6 subunit of integrins in the development and sex differentiation of the mouse ovary
Authors: Fröjdman Kim , Pelliniemi Lauri J. 
Published: February 2005

AbstractThe localization of the α6 subunit of integrins in the ovary was studied by conventional and immunolabeling light and electron microscopy starting from the pregonadal embryonic phase until adulthood. The formation of gonadal blastema cells included an initial expression of the α6 subunit on the plasma membranes of all blastema cells. Subsequently the reaction for the α6 subunit became restricted in groups of these cells, which differentiated into gonadal cord cells, the precursors of follicular cells. The α6 subunit was also found in the cells of the mesonephric duct, mesonephric tubules, and the ovarian rete. Reorganization of the gonadal cords into follicles at birth was accompanied with strong and uniform re‐expression of the α6 subunit on the surface of the cord cells. Vascular endothelial cells and the cells of the postnatal surface epithelium remained positive for the α6 integrin subunit. In larger follicles, the intensity of the reaction for the integrin subunit varied. The theca cells of growing follicles contained the α6 subunit. The results show that this subunit of integrins is present in phases of increased adhesion and aggregation, and that its expression probably is involved in the regulation of ovarian epithelial differentiation. The distribution of α6 integrin in ovarian cells shows potentially important sex‐specific and developmental differences in epithelial organization when compared with respective changes found earlier by us in the male gonad. © 1995 Wiley‐Liss, Inc.
Epithelial cell polarity in early Xenopus development
Authors: Müller H.‐Arno J. , Hausen Peter 
Published: February 2005

AbstractThe Xenopus blastula consists of two morphologically distinct cell types. Polarized epithelial cells build up the embryonic surface and fence off an inner non‐polarized cell population. We examined the establishment of this early functional cell diversification in the embryo by single cell analysis, in vitro cell culture, and transplantation experiments. Single blastomeres from a 64‐cell embryo (1/64 cells) exhibit several features of polarized cells. The plasma membrane of 1/64 cells consists of an apical domain, which is inherited from the original egg membrane, and a basolateral domain derived from newly formed membrane during cleavage. These are inherent, cell‐autonomous properties of the blastomeres, as they form and are maintained in blastomeres raised in the absence of any cell interactions in calcium free medium. Upon in vitro culture a single 1/64 cell gives rise to an aggregate of two different cell types. Cells carrying a part of the former egg membrane domain differentiate into polarized epithelial cells, whereas cells lacking this membrane domain are not polarized. These results demonstrate that the inclusion of the egg membrane, rather than external signals related to the position of a cell in the intact embryo, is required for the apical/basolateral differentiation of the surface epithelium. This view is supported by cell transplantation studies. A single 1/64 cell was implanted into the blastocoel of a stage 8 blastula embryo. The progeny of the implanted cell proliferate within the host embryo and split into two morphologically distinct populations with different cell behaviours. Cells incorporating a part of the egg membrane form coherent patches of polarized epithelial cell sheets in the interior of the host embryo. In contrast, cells lacking egg membrane do not exhibit any characteristics of polarized cells and eventually spread into different regions of the host embryo. Our results show that the egg membrane and/or components of the submembrane cortex play a determinative role in the formation of the blastula epithelium. © 1995 Wiley‐Liss, Inc.
Involvement of extracellular matrix in the formation of the inner ear
Authors: Gerchman Eric , Hilfer S. Robert , Brown Joyce W. 
Published: February 2005

AbstractFormation of the inner ear from the otic placode differs from invagination of other cup‐shaped organ primordia. Activation of the actin cytoskeleton seems to play a limited role because precocious invagination does not occur upon treatment with activators of a contractile event and cannot be prevented by inhibitors. In this study, the possibility that invagination is mediated by changes in the surrounding mesenchyme was tested by treating embryos with agents which interfere with the integrity of extracellular matrix. Enzymes degrading hyaluronate and/or chondroitin sulfate were microinjected into the otic region prior to folding. Synthesis of chondroitin sulfate proteoglycan was inhibited by microinjection of β‐xyloside. All treatment inhibited otic pit formation by interfering with fold formation within the placode. Immunocytochemical procedures showed depletion of the appropriate extracellular matrix components for a short time period after enzyme treatments and for up to 24 hr after β‐xyloside injection. Invagination of the otic primordium is concluded to be controlled in part by anchorage of the epithelium to adjacent structures and possibly by expansion of the mesenchymal extracellular matrix. © 1995 Wiley‐Liss, Inc.
Cell cycle of globose basal cells in rat olfactory epithelium
Authors: Huard Josée M. T. , Schwob James E. 
Published: February 2005

AbstractThe olfactory epithelium of adult mammals has the unique property of generating olfactory sensory neurons throughout life. Cells of the basal compartment, which include horizontal and globose basal cells, are responsible for the ongoing process of neurogenesis in this system. We report here that the globose basal cells in olfactory epithelium of rats, as in mice, are the predominant type of proliferating cell, and account for 97.6% of the actively dividing cells in the basal compartment of the normal epithelium. Globose basal cells have not been fully characterized in terms of their proliferative properties, and the dynamic aspects of neurogenesis are not well understood. As a consequence, it is uncertain whether cell kinetic properties are under any regulation that could affect the rate of neurogenesis. To address this gap in our knowledge, we have determined the duration of both the synthesis phase (S‐phase) and the full cell cycle of globose basal cells in adult rats. The duration of the S‐phase was found to be 9 hr in experiments utilizing sequential injections of either IdU followed by BrdU or 3H‐thy followed by BrdU. The duration of the cell cycle was determined by varying the time interval between the injections of 3H‐thy and BrdU and tracking the set of cells that exit S shortly after the first injection. With this paradigm, the interval required for these cells to traverse G2, M, G1, and a second S‐phase, is equivalent to the duration of one mitotic cycle and equals 17 hr. These observations serve as the foundation to assess whether the cell cycle duration is subject to regulation in response to experimental injury, and whether such regulation is partly responsible for changes in the rate of neurogenesis in such settings. ©1995 Wiley‐Liss, Inc.
Mechanics of cardiac looping
Authors: Taber Larry A. , Lin I.‐En , Clark Edward B. 
Published: February 2005

AbstractDuring the early stages of embryonic development, the heart is a smooth‐walled, muscle‐wrapped tube that bends and rotates in a vital, but poorly understood, morphogenetic process called looping. Since looping involves biomechanical forces, this paper examines two mechanically based hypotheses for the bending component of cardiac looping. The first hypothesis is that an initial tension in or near the dorsal mesocardium (DM), a longitudinal structure along the outside of the ventricle, drives the deformation. To relieve the bending stresses in the tube, the myocytes change shape passively, and then they deform actively to continue the process to completion of a full loop. In the second hypothesis, contraction of circumferentially arranged actin macrofilaments produces circumferential compression and longitudinal expansion (due to incompressibility) of the myocytes. The DM locally constrains the longitudinal deformation, forcing the tube to bend. The feasibility of these hypotheses was evaluated using theoretical models and published experimental results. The models, which consist of beams composed of two layers representing the DM and the ventricular myocardium, show that the hypotheses are consistent with most of the known data, but further studies are necessary. In this regard, the models provide a conceptual framework for designing experiments to investigate the mechanics of looping. ©1995 Wiley‐Liss, Inc.
Vascularization of the mouse embryo: A study of flk‐1, tek, tie, and vascular endothelial growth factor expression during development
Authors: Dumont Daniel J. , Fong Guo‐Hua , Puri Mira C. , Gradwohl Gérard , Alitalo Kari , Breitman Martin L. 
Published: February 2005

AbstractWe report the detailed developmental expression profiles of three endothelial specific receptor tyrosine kinases (RTKs) flk‐1, tek, tie, as well as vascular endothelial growth factor (VEGF), the flk‐1 ligand. We also examined the expression of the other VEGF receptor, flt‐1, during placental development.flk‐1, tek, and tie transcripts were detected sequentially at one‐half day intervals starting at E7.0, suggesting that each of these RTKs play a unique role during vascularization of the mouse embryo. All three RTKs were expressed in the extraembryonic and embryonic mesoderm in regions that eventually give rise to the vasculature. Except for the expression of tek and flk‐1 in the mesoderm of the amnion, the expression of these RTKs from E8.5 onwards was virtually indistinguishable. An abundant amount of flt‐1 transcripts was found in the spongiotrophoblast cells of the developing placenta from E8.0 onwards. This cellular compartment is located between the maternal and labyrinthine layers of the placenta, which both express VEGF. VEGF transcripts were detected as early as E7.0 in the endoderm juxtaposed to the flk‐1 positive mesoderm, and later in development VEGF expression displayed an expression profile both contiguous with that of flk‐;1, and also in tissues found some distance from the flk‐1‐expressing endothelium. These results suggest a possible dual role for VEGF which includes a chemotactic and/or a cellular maintenance role for VEGF during vascularization of the mouse embryo. ©1995 Wiley‐Liss, Inc.
Sequential expression and differential localization of I‐, L‐, and T‐Fimbrin during differentiation of the mouse intestine and yolk sac
Authors: Chafel Mark M. , Shen Wenyan , Matsudaira Paul 
Published: February 2005

AbstractDuring the differentiation of the intestine epithelium, three cytoskeletal proteins, villin, fimbrin, and myosin I, are sequentially expressed and localized to the apical membrane. Recently, we found that in the adult mouse and human, three fimbrin isoforms are expressed in a cell specific manner. I‐fimbrin is expressed by intestine and kidney epithelial cells, L‐fimbrin is expressed by leukocytes and many tumors, while T‐fimbrin is expressed by various cells and tissues. Because non‐intestinal isoforms of fimbrin could be expressed early in development, the expression of fimbrin isoforms during days 10.5 to 16.5 of intestine development was investigated. By immunofluorescence microscopy, T‐fimbrin was detected in the early stages of intestinal epithelial cell differentiation until day 14.5 and was localized predominantly at the apical surface. L‐fimbrin was also detected during this period but it was localized to the basal surface of the epithelium instead of the apical surface. By day 16.5 no L or T‐fimbrin was detected in the epithelium. I‐fimbrin was first detected at day 14.5 and a brush border‐like apical localization pattern was seen by day 16.5. Unlike the intestinal cells, the visceral endoderm expressed I, L, and T‐fimbrin throughout the period examined, with the level of I‐fimbrin increasing as time progresses. L‐fimbrin was more evident at the earlier stage than at the later stage of the development. Collectively, these results suggest that three fimbrin isoforms play different roles during epithelial cell differentiation. T‐ and I‐fimbrin expression could be critical for the formation and extension of the microvilli whereas L‐fimbrin may play a role in controlling cell adhesion. ©1995 Wiley‐Liss, Inc.
Proliferation pattern of capillary endothelial cells in chorioallantoic membrane development indicates local growth control, which is counteracted by vascular endothelial growth factor application
Authors: Kurz Haymo , Ambrosy Sonja , Wilting Jörg , Marmé Dieter , Christ Bodo 
Published: February 2005

AbstractThe density and distribution of whole mount BrdU‐anti‐BrdU labeled endothelial cells (days 6–15) in the chick chorioallantoic membrane (CAM) was analyzed with computer‐assisted microscopy. A significant loss of proliferative activity was noted after day 10: the density of labeled nuclei (in 10−2 mm−2) decreased from a median 7.78 (days 6, 8, 10) to 2.42 (days 12, 14, 15). CAMs initially showed random patterns of labeled endothelial cells, but changed to clearly focal patterns after day 12. A regular arrangement of labeled nuclei was never seen. After application of vascular endothelial growth factor (VEGF) to the day 13 CAM, a significant increase in proliferative activity (11.50) and a random distribution of labeled endothelial cells was observed on day 15. Development of CAM precapillary vessels was assessed in terms of length density (in mm−1, mean ± standard deviation), which was augmented threefold from day 6 (1.22 ± 0.05) to day 14 (3.54 ± 0.23) and then remained nearly constant. VEGF application from day 13 to 15 raised arterial length per unit area to 4.53 ± 0.77. It is concluded that normally a local regulation of endothelial proliferation and differentiation develops in the CAM, which doubles capillary endothelial cell density but simultaneously adapts to the decreasing need for endothelial cells, and thus maintains the quasi two‐dimensional vessel pattern. However, proliferative foci persist in the capillary layer after day 10, and precapillary vessel density continues to increase until day 14. VEGF enhances DNA synthesis in all capillary endothelial cells. This leads to the disappearance of proliferative foci, to multiple capillary layers, and to an excessive formation of precapillary vessels. We propose that CAM endothelial cell proliferation is regulated by factors like endothelial cell density and extension. The proliferative pattern in capillaries, and the length density of precapillary vessels should be used for the evaluation of angiogenesis in the CAM assay. We recommend the CAM after day 12 for evaluating putative angiogenic mitogens. ©1995 Wiley‐Liss, Inc.
Galectin‐3 is expressed in the notochord, developing bones, and skin of the postimplantation mouse embryo
Authors: Fowlis Deborah , Colnot Céline , Ripoche Marie‐Anne , Poirier Françoise 
Published: February 2005

AbstractThe galectins are a family of low molecular weight, calcium‐independent mammalian carbohydrate binding proteins that exhibit specificity for beta‐galactoside derivatives. We have examined the expression pattern of galectin‐3 in the developing mouse embryo by in situ hybridisation and immunohistochemistry. In the embryo proper, galectin‐3 message and protein are first detected in notochord, starting from 8.5 days post coitum (dpc), and persist until this structure disappears. Galectin‐3 is later found in cartilage primordia and in developing skin from 13.5 dpc. This very restricted and dynamic pattern suggests that galectin‐3 may participate in the establishment and/or maintenance of notochord as well as the formation of cartilage and differentiation of skin. Finally, we find that galectin‐3, which is identical to the macrophage marker Mac‐2, is also expressed in embryonic macrophages. © 1995 Wiley‐Liss, Inc.
Stages of embryonic development of the zebrafish
Authors: Kimmel Charles B. , Ballard William W. , Kimmel Seth R. , Ullmann Bonnie , Schilling Thomas F. 
Published: February 2005

AbstractWe describe a series of stages for development of the embryo of the zebrafish, Danio (Brachydanio) rerio. We define seven broad periods of embryogenesis—the zygote, cleavage, blastula, gastrula, segmentation, pharyngula, and hatching periods. These divisions highlight the changing spectrum of major developmental processes that occur during the first 3 days after fertilization, and we review some of what is known about morphogenesis and other significant events that occur during each of the periods. Stages subdivide the periods. Stages are named, not numbered as in most other series, providing for flexibility and continued evolution of the staging series as we learn more about development in this species. The stages, and their names, are based on morphological features, generally readily identified by examination of the live embryo with the dissecting stereomicroscope. The descriptions also fully utilize the optical transparancy of the live embryo, which provides for visibility of even very deep structures when the embryo is examined with the compound microscope and Nomarski interference contrast illumination. Photomicrographs and composite camera lucida line drawings characterize the stages pictorially. Other figures chart the development of distinctive characters used as staging aid signposts. ©1995 Wiley‐Liss, Inc.
Gsh‐1: A novel murine homeobox gene expressed in the central nervous system
Authors: Valerius M. Todd , Li Hung , Stock Jeffrey L. , Weinstein Michael , Kaur Satbir , Singh Gurparkash , Potter S. Steven 
Published: February 2005

AbstractWe report the characterization of Gsh‐1, a novel murine homeobox gene. Northern blot analysis revealed a transcript of approximately 2 kb in size present at embryonic days 10.5, 11.5, and 12.5 of development. The cDNA sequence encoded a proline rich motif, a polyalanine tract, and a homeodomain with strong homology to those encoded by the clustered Hox genes. The Gsh‐1 expression pattern was determined for days E8.5 to E13.5 by whole mount and serial section in situ hybridizations. Gsh‐1 transcription was restricted to the central nervous system. Expression is present in the neural tube and hindbrain as two continuous, bilaterally symmetrical stripes within neural epithelial tissue. In the mesencephalon, expression is seen as a band across the most anterior portion. There is also diencephalon expression in the anlagen of the thalamus and the hypothalamus as well as in the optic stalk, optic recess, and the ganglionic eminence. Moreover, through the use of fusion proteins containing the Gsh‐1 homeodomain, we have determined the consensus DNA ninding site of the Gsh‐1 homeoprotein to be GCT/CA/CATTAG/A. ©1995 Wiley‐Liss, Inc.
Collagen gene expression during development of avian synovial joints: Transient expression of types II and XI collagen genes in the joint capsule
Authors: Nalin Andrew M. , Greenlee Theodore K. , Sandell Linda J. 
Published: February 2005

AbstractThe developmental sequence of the embryonic joint has been well studied morphologically. There are, however, no definitive studies of cell function during joint development. In order to begin to understand the differentiation events that contribute to joint formation, we examined the expression of collagen mRNAs encoding types I, IIA, IIB, and XI. In situ hybridization was performed on chicken embryo hind limb buds and digits from day 7 to day 18 (Hamburger and Hamilton stages 31–44). In the day 7 (stage 31) limb bud, there was a condensation of mesenchyme forming the primitive tarsal and metatarsal bones that showed abundant expression of type IIA procollagen message, but no type IIB or type α1(XI) message. By day 8 (stage 33), co‐expression of types IIA, and type XI procollagen mRNAs was observed in the condensations, with expression of IIB restricted to early chondrocytes with metachromatically staining matrix. At this stage, DNA fragmentation characteristic of apoptosis was observed in cells near the midline of the interzone region between the developing anlagen, and in areas between and around the individual digits of the paddle. The presumptive apoptotic cells were more numerous at day 9 (stage 35), and were not found in the developing joint at subsequent time points, including the initiation of spatial cavitation of the joint. From days 11–18, type IIA procollagen mRNA was expressed in flattened cells at the surface of the anlagen, and in the perichondrium and in the developing joint capsule; type IIB mRNA message was found only in chondrocytes. Type XI mRNA was expressed by all type II‐expressing cells. Alpha 1(I) mRNA was expressed early by cells of th8e interzone and capsule, but as cavitation progressed, the type I expressing cells of the interzone merged with the superficial layer of the articular surface. Thus, at the time of joint cavitation, there was a distinct pattern of expression of procollagen messages at the articular surface, with type I being outermost, followed by morphologically similar cells expressing type IIA, then chondrocytes expressing type IIB. The progenitor cells expressing type IIA message define a new population of cells. These cell populations contribute to the molecular heterogeneity of the articular cartilage, and these same populations likely exist in the developing joints of other species. The transient transcription of type II and type XI collagen genes, characteristic of chondrocytes, by cells in the joint capsule demonstrates that these cells may have chondrogenic potential. ©1995 Wiley‐Liss, Inc.
Homozygosity for theMinallele ofApcresults in disruption of mouse development prior to gastrulation
Authors: Moser Amy Rapaich , Shoemaker Alex R. , Connelly Camille S. , Clipson Linda , Gould Karen A. , Luongo Cindy , Dove William F. , Siggers Pamela H. , Gardner Richard L. 
Published: February 2005

AbstractMutation of theAPC(adenomatous polyposis coli) gene is an early event in colon tumor development in humans. Mice carryingMin(multiple intestinal neoplasia), a mutant allele ofApc, develop intestinal and mammary tumors as adults. To study the role of theApcgene in development, we have investigated the phenotype of embryos homozygous forApcMin(Min). Development of the primitive ectoderm fails prior to gastrulation in homozygousMinembryos. By midgestation, the presumed homozygotes consist of a mass of trophoblast giant cells with an additional cluster of much smaller embryonic cells. These results indicate that functional Apc is required for normal growth of inner cell mass derivatives. ©1995 Wiley‐Liss, Inc.