DOCSLIB.ORG

For Proteoglycans in Neurulation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
For Proteoglycans in Neurulation J. Anat. (1982), 134, 3, pp. 491-506 491 With 16figures Printed in Great Britain Culture of rat embryos with p-D-xyloside: evidence of a role for proteoglycans in neurulation GILLIAN M. MORRISS-KAY AND BETH CRUTCH Department ofHuman Anatomy, University of Oxford (Accepted 1 May 1981) INTRODUCTION The synthesis of sulphated glycosaminoglycans by early post-implantation rat embryos occurs at very low levels until the onset of neurulation, at which time there is an increase in the level ofsynthesis (as indicated by [3H]glucosamine incorporation) of chondroitin/chondroitin sulphate and heparan sulphate (Solursh & Morriss, 1977). In embryos undergoing neurulation, histochemical staining techniques have indicated that these sulphated glycosaminoglycans are localised in the ectodermal basement membrane and in the extracellular matrix and cell surface-associated material of the mesenchyme. The staining intensity is higher in the neural fold region than elsewhere in the embryo. They are probably present in the form of proteoglycan in association with hyaluronate (Morriss & Solursh, 1978a). In order to investigate further these stage and position-related histochemical differences, we have cultured rat embryos in vitro during neurulation and early somitogenesis in the presence of the xylose-derivative, /8-D-xyloside. This substance has been shown to bring about a reduction in the level of synthesis of protein-bound chondroitin sulphate and an increase in free chondroitin sulphate chains in both chondrogenic and non-chondrogenic systems (Schwartz, Ho & Dorfman, 1976; Galligani, Hopwood, Schwartz & Dorfman, 1975). Its activity is due to interference with the sequence of normal chondroitin sulphate-proteoglycan synthesis, as fol- lows. Prior to chondroitin sulphate chain synthesis, three sugar molecules, xylose and two galactose molecules, are added sequentially to certain serines of the core protein (for review, see Roden & Schwartz, 1975). /5-D-xyloside competes with protein-bound xylose for the enzyme galactosyl transferase, and thereby acts as an initiation site for galactose-linked chondroitin sulphate chain synthesis (Fukanaga et al. 1975; Schwartz, 1977). Schwartz (1979) found that in chondroitin sulphate- proteoglycan formed by cultured chondrocytes in the presence of 1 mM ,-D-xyloside, the degree of substitution of core protein serine residues with chondroitin sulphate chains was reduced by 60 %, but there were only minor reductions in chain length and degree of sulphation. Furthermore, there was an increase of serine-bound chondroitin sulphate within the cells, suggesting that transport of the low-carbo- hydrate proteoglycan molecules to the extracellular matrix was impaired. /?-D-xylo- side itself stimulates chondroitin sulphate synthesis (Galligani et al. 1975). These free chondroitin sulphate chains differ from the protein-bound chains in being short and under-sulphated (Gibson, Segen & Audhya, 1977). ,f-D-xyloside-induced reduction of proteoglycan synthesis has also been demon- strated in whole embryo systems: chick (Gibson, Segen & Doller, 1979) and sea urchin (Kinoshita & Saiga, 1979), where it was associated with abnormal morpho- genesis. In the present study, we have analysed its effect on development, particularly 492 GILLIAN M. MORRISS-KAY AND BETH CRUTCH of the cranial neural folds, in rat embryos. Our purpose was to elucidate the morpho- genetic significance of the sulphated glycosaminoglycans present at this stage, and to discover whether they are present in the form of proteoglycan. These results were presented briefly to the Anatomical Society in December 1980 (Morriss-Kay & Crutch, 1981). MATERIALS AND METHODS Embryo culture Wistar strain rat embryos were explanted in Tyrode's saline on the afternoon of day 9 ofpregnancy (day ofpositive vaginal smear = day 0) and Reichert's membrane was opened. They were cultured at 38 °C in 60 ml bottles, each containing 5 ml medium. The bottles were rotated at 30 rev/min. The culture medium consisted of 2-5 ml Tyrode's saline (with or without 8-D-xyloside) and 2 5 ml immediately centrifuged, heat-inactivated rat serum (Steele & New, 1974) with 50 pg/ml strepto- mycin. 8l-D-xyloside (p-nitrophenyl-,8-D-xylopyranoside, Koch-Light) was added from a stock solution (1I35 mg in 100 ,ul Tyrode's saline) to give a final concentra- tion of 1 mm. The explanted embryos were at the late presomite to very early somite stage (flat neural plate to slightly convex neural folds; Morriss & Solursh, 1978b), and were carefully matched for allocation to control and experimental groups, with a maximum of six embryos per bottle. 95 control and 101 experimental embryos were cultured for periods ranging from 15 to 30 hours. The bottles were first gassed with 5 %20/5 % C02/90 % N2 (New, Coppola & Cockroft, 1976a, b). Cultures continued after 24 hours were regassed with 5 % CO2 in air. When the cultures were terminated the embryos were washed in Tyrode saline and the membranes dissected off. They were examined and photographed whole, either unfixed (prior to prepara- tion for paraffin embedding) or after glutaraldehyde fixation (prior to preparation for electron microscopy). In order to confirm the specificity of /-D-xyloside in this system, two related p-nitrophenol derivatives (p-nitrophenyl-fi-D-glucopyranoside and p-nitrophenyl- ,8-D-galactopyranoside) and free xylose were tested at 1 mm in 24 hour cultures (other details as above). Each of these cultures contained four day 9 embryos. After 24 hours the membranes were dissected off and the embryos were examined with the dissecting microscope in order to assess development (somite numbers, development and form of the neural folds, etc.) in comparison with co-cultured control embryos. They were not processed further. For histology, embryos were fixed in one quarter-strength Bouin's fluid, paraffin- embedded, cut at 5 /zm, and stained with haematoxylin and eosin. For histochemistry, five control and five /J-D-xyloside-cultured embryos were fixed after a 3 hour culture period in Bouin's fluid (one embryo), Carnoy's fluid (two embryos), and Carnoy's fluid containing 100 mg/ml cetylpyridinium chloride (CPC) (two embryos). They were paraffin-embedded, cut at 8 #zm and mounted four sections per slide. Adjacent slides were either stained immediately with alcian blue at pH 1, or stained with alcian blue at pH 1 following 3 hours incubation with 0-1 M phosphate buffer (pH 5 6) with or without 400 units/ml purified, protease-free testicular hyaluronidase (Worthington; degrades hyaluronate, chondroitin, and chondroitin sulphatesA & C). Six control and five experimental embryos, cultured for 15 hours, and five control and five experimental embryos, cultured for 24 hours, were used for electron microscopy. They were fixed with 2-5 % cacodylate-buffered glutaraldehyde (0-1 M, pH 7-2, with fl-D-xyloside: effects on neurulation 493 -5mm~~~~~~~~ Fig. 1. Embryos cultured for 17 hours. Control (upper) has 9 pairs of somites; the cranial neural epithelium has a V-shaped profile and its junction with the surface ectoderm (arrow) is clear. Anteriorly, the two sides of the anterior forebrain are approaching each other. The f6-D-xyloside- cultured embryo (lower), with 8 pairs of somites, has a much broader neural epithelium whose lateral edge forms the border of the head from this viewpoint. In the anterior forebrain region, the neural epithelium is everted instead of concave. Fig. 2. The same embryos as in Fig. 1, to show clearly outlined somites in the control (upper) compared with less distinct somitic mesoderm in the 8l-D-xyloside-cultured embryo (lower). Both embryos show close apposition, probably fusion, of the neural folds to form neural tube in the somitic region. 494 GILLIAN M. MORRISS-KAY AND BETH CRUTCH 2 mm CaCl2), washed in buffer, post-fixed in 1 % cacodylate-buffered osmium tetroxide, dehydrated, and embedded individually in Spurr resin. They were orienta- ted at this stage, and during cutting, so that all sections were cut perpendicular to the long axis of the embryo. 1 ,um sections were mounted on glass slides and stained with 05 % methylene blue/0 5 % azure II in 0 5 % borax for reference; thin sections were stained with lead citrate and uranyl acetate. RESULTS Embryos cultured for 24 hours in the presence ofp-nitrophenol derivatives other than .,-D'-xyloside (p-nitrophenyl-/6-D-glucopyranoside and p-nitrophenyl-f6-D- galactopyranoside) and free xylose were examined with the dissecting microscope after removal of their membranes. They showed no morphological abnormalities when compared with co-cultured control embryos. The morphological abnormalities reported: below are therefore regarded as a specific effect of fl-D-xyloside on em- bryonic. development. Morphogepesis ofcultured embryos During formation of the first four pairs of somites, the cranial neural folds of control embryos developed as increasingly convex structures. Subsequently, up to the 9 somite stage, the cranial neural plate/surface ectoderm boundary formed an angle wich became progressively sharper as the neural folds increased in height and became V-shaped in profile (Fig. 1). Cranial neural tube closure was completed at the 14 somnite stage, after approximately 24 hours ofculture. (This sequence of events is described and illustrated more fully in Morriss & New, 1979.) The earliest (convex) stages of cranial neural fold formation in /5-D-xyloside- cultured embry6o were apparently normal, although somite formation proceeded at a slower rate than in controls, and the somites themselves were less distinct (Fig. 2). Subseq'uently, the cranial neural folds continued to enlarge but retained their convex shape, so that in contrast to control embryos, a clear boundary did not develop between neural and surface ectoderms in embryos cultured for 15-17 hours; these embryos had 5-8 pairs of somites, cf. 6-10 in controls (Fig. 1). By 24 hours a neural/surface ectodermal angle had developed, but the neural ectoderm was itself still convex in profile.; embryos cultured for longer periods (up to 30 hours) did not progress further'towkrds closure of the cranial neural tube. The anterior forebrain region developed as.
Load more

Recommended publications
  • Sox9 Is Required for Invagination of the Otic Placode in Mice ⁎ Francisco Barrionuevo A, , Angela Naumann B, Stefan Bagheri-Fam A,1, Volker Speth C, Makoto M
    Available online at www.sciencedirect.com Developmental Biology 317 (2008) 213–224 www.elsevier.com/developmentalbiology Sox9 is required for invagination of the otic placode in mice ⁎ Francisco Barrionuevo a, , Angela Naumann b, Stefan Bagheri-Fam a,1, Volker Speth c, Makoto M. Taketo d, Gerd Scherer a, Annette Neubüser b a Institute of Human Genetics and Anthropology, University of Freiburg, Breisacherstr. 33, D-79106 Freiburg, Germany b Developmental Biology, Institute of Biology 1, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany c Cell Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany d Department of Pharmacology, Graduate School of Medicine, Kyoto University, Yoshida-Konoé-cho, Sakyo-ku, Kyoto 606-8501, Japan Received for publication 20 December 2007; revised 7 February 2008; accepted 8 February 2008 Available online 21 February 2008 Abstract The HMG-domain-containing transcription factor Sox9 is an important regulator of chondrogenesis, testis formation and development of several other organs. Sox9 is expressed in the otic placodes, the primordia of the inner ear, and studies in Xenopus have provided evidence that Sox9 is required for otic specification. Here we report novel and different functions of Sox9 during mouse inner ear development. We show that in mice with a Foxg1Cre-mediated conditional inactivation of Sox9 in the otic ectoderm, otic placodes form and express markers of otic specification. However, mutant placodes do not attach to the neural tube, fail to invaginate, and subsequently degenerate by apoptosis, resulting in a complete loss of otic structures. Transmission-electron microscopic analysis suggests that cell–cell contacts in the Sox9 mutant placodes are abnormal, although E-cadherin, N-cadherin, and beta-catenin protein expression are unchanged.
    [Show full text]
  • And Krox-20 and on Morphological Segmentation in the Hindbrain of Mouse Embryos
    The EMBO Journal vol.10 no.10 pp.2985-2995, 1991 Effects of retinoic acid excess on expression of Hox-2.9 and Krox-20 and on morphological segmentation in the hindbrain of mouse embryos G.M.Morriss-Kay, P.Murphy1,2, R.E.Hill1 and in embryos are unknown, but in human embryonal D.R.Davidson' carcinoma cells they include the nine genes of the Hox-2 cluster (Simeone et al., 1990). Department of Human Anatomy, South Parks Road, Oxford OXI 3QX The hindbrain and the neural crest cells derived from it and 'MRC Human Genetics Unit, Western General Hospital, Crewe are of particular interest in relation to the developmental Road, Edinburgh EH4 2XU, UK functions of RA because they are abnormal in rodent 2Present address: Istituto di Istologia ed Embriologia Generale, embryos exposed to a retinoid excess during or shortly before Universita di Roma 'la Sapienza', Via A.Scarpa 14, 00161 Roma, early neurulation stages of development (Morriss, 1972; Italy Morriss and Thorogood, 1978; Webster et al., 1986). Communicated by P.Chambon Human infants exposed to a retinoid excess in utero at early developmental stages likewise show abnormalities of the Mouse embryos were exposed to maternally administered brain and of structures to which cranial neural crest cells RA on day 8.0 or day 73/4 of development, i.e. at or just contribute (Lammer et al., 1985). Retinoid-induced before the differentiation of the cranial neural plate, and abnormalities of hindbrain morphology in rodent embryos before the start of segmentation. On day 9.0, the RA- include shortening of the preotic region in relation to other treated embryos had a shorter preotic hindbrain than the head structures, so that the otocyst lies level with the first controls and clear rhombomeric segmentation was pharyngeal arch instead of the second (Morriss, 1972; absent.
    [Show full text]
  • 20. Placodes and Sensory Development
    PLACODES AND 20. SENSORY DEVELOPMENT Letty Moss-Salentijn DDS, PhD Dr. Edwin S. Robinson Professor of Dentistry (in Anatomy and Cell Biology) E-mail: [email protected] READING ASSIGNMENT: Larsen 3rd Edition Chapter 12, Part 2. pp.379-389; Part 3. pp.390- 396; Chapter 13, pp.430-432 SUMMARY A series of ectodermal thickenings or placodes develop in the cephalic region at the periphery of the neural plate. Placodes are central to the development of the cranial sensory systems in vertebrates and are among the innovations that appeared in the early evolution of vertebrates. There are placodes for the three organs of special sense: olfactory, optic (lens) and otic placodes, and (epibranchial) placodes that give rise to the distal cells of the sensory ganglia of cranial nerves V, VII, IX and X. Placodes (with the possible exception of the olfactory placodes) form under the influence of surrounding cranial tissues. They do not appear to require the presence of neural crest. The mesoderm in the prechordal plate plays a significant role in the initial development of the placodes for the organs of special sense, while the pharyngeal pouch endoderm plays that role in the development of the epibranchial placodes. The development of the organs of special sense is described briefly. LEARNING OBJECTIVES You should be able to: a. Give a definition of placodes and describe their evolutionary significance. b. Name the different types of placodes, their locations in the developing embryo and their developmental fates. c. Discuss the early development of the placodes and some of the possible factors that feature in their development.
    [Show full text]
  • Otic Capsule Or Bony Labyrinth
    DEVELOPMENT OF EAR BY DR NOMAN ULLAH WAZIR DEVELOPMENT OF EAR The ears are composed of three anatomic parts: External ear: • Consisting of the auricle , external acoustic meatus, and the external layer of the tympanic membrane. Middle ear: • The internal layer of the tympanic membrane, and three small auditory ossicles, which are connected to the oval windowsof the internal ear. • Internal ear: Consisting of the vestibulocochlear organ, which is concerned with hearing and balance. • The external and middle parts of the ears are concerned with the transference of sound waves to the internal ears, which convert the waves into nerve impulses and registers changes in equilibrium. DEVELOPMENT OF INTERNALEAR The internal ears are the first to develop. • Otic placode: Early in the 4th week, a thickening of surface ectoderm takes place on each side of the myelencephalon,the caudal part of thehindbrain. • Inductive signals from the paraxial mesoderm and notochord stimulate the surface ectoderm to form theplacodes. • Each otic placode soon invaginates and sinks deep to the surface ectoderm into the underlying mesenchyme. • In so doing, it forms an otic pit. • The edges of the pit come together and fuse to forman otic vesicle the primordium of the membranous labyrinth. • The otic vesicle soon loses its connection with the surface ectoderm. • A diverticulum (endolymohatic appendage) grows from the vesicle and elongates to form the endolymphatic duct and sac. the rest of the oticvesicle differentiates into an expanded pars superior (Ventral saccularparts, which give rise to the sacculeand cochlearducts) and an initially tapered pars inferior (Dorsal utricular parts, from which thesmall endolymphaticducts, utricles and semicircular ductsarise).
    [Show full text]
  • Olfactory Epithelium: Development of the Nose Olfactory Epithelium: Development of the Nose
    DEVELOPMENT OF THE HEAD AND NECK PlacodesPlacodes andand thethe developmentdevelopment ofof organsorgans ofof specialspecial sensesense LL.. MMoossss--SaSalelentijnntijn Innovations in the early evolution of vertebrates ! DDeevveellooppmmeenntt ooff oorrggaannss ooff ssppeecciiaall sseennssee ((ppllaaccooddeess)) ! DDeevveellooppmmeenntt ooff aa llaarrggee nneeuurraall cciirrccuuiittrryy ((tthhee bbrraaiinn)) ttoo iinntteeggrraattee iinnppuutt aanndd rreessppoonnsseess ! DDeevveellooppmmeenntt ooff aann eeffffeeccttiivvee ffeeeeddiinngg aappppaarraattuuss (jaws)(jaws) ! DDeevveellooppmmeenntt ooff aann iimmpprroovveedd rreessppiirraattoorryy aappppaarraattuuss ((ggiillllss)) PLACODES Localized thickened areas of specialized ectoderm, lateral to the neural crest, at the border between neural plate and the future epidermis Brugmann SA, Moody SA (2005) Brugmann SA, Moody SA (2005) NEURAL PLATE NEURAL GROOVE Example: otic placode. Different kinds of placodes ! CCoonnttrriibbuuttiinngg ttoo oorrggaannss ooff ssppeecciiaall sseennssee:: "OlfactoryOlfactory "LensLens (only(only placodeplacode thatthat doesdoes notnot havehave neuralneural fate)fate) "OticOtic ! ContributingContributing toto distaldistal gangliaganglia ofof branchiomericbranchiomeric nneerrvveess:: "TrigeminalTrigeminal (Ophthalmic,V1)(Ophthalmic,V1) "EpibranchialEpibranchial (4)(4) ! Hypobranchial (2) (contribute to hypobranchial ganglia - frog only; not in chick, mouse, zebrafish) Distribution of placodes at 3 developmental stages A. Initial induction of placodes in pre-placodal
    [Show full text]
  • Fgfr1 Regulates Patterning of the Pharyngeal Region
    Downloaded from genesdev.cshlp.org on September 30, 2021 - Published by Cold Spring Harbor Laboratory Press Fgfr1 regulates patterning of the pharyngeal region Nina Trokovic, Ras Trokovic, Petra Mai, and Juha Partanen1 Institute of Biotechnology, Viikki Biocenter, 00014-University of Helsinki, Finland Development of the pharyngeal region depends on the interaction and integration of different cell populations, including surface ectoderm, foregut endoderm, paraxial mesoderm, and neural crest. Mice homozygous for a hypomorphic allele of Fgfr1 have craniofacial defects, some of which appeared to result from a failure in the early development of the second branchial arch. A stream of neural crest cells was found to originate from the rhombomere 4 region and migrate toward the second branchial arch in the mutants. Neural crest cells mostly failed to enter the second arch, however, but accumulated in a region proximal to it. Both rescue of the hypomorphic Fgfr1 allele and inactivation of a conditional Fgfr1 allele specifically in neural crest cells indicated that Fgfr1 regulates the entry of neural crest cells into the second branchial arch non-cell- autonomously. Gene expression in the pharyngeal ectoderm overlying the developing second branchial arch was affected in the hypomorphic Fgfr1 mutants at a stage prior to neural crest entry. Our results indicate that Fgfr1 patterns the pharyngeal region to create a permissive environment for neural crest cell migration. [Keywords: Craniofacial development; fibroblast growth factor; branchial arch; hindbrain; neural crest; cell migration; cleft palate; Cre recombinase] Supplemental material is available at http://www.genesdev.org. Received October 1, 2002; revised version accepted October 17, 2002. Branchial arches of vertebrate embryos are transient (Lumsden and Krumlauf 1996; Rijli et al.
    [Show full text]
  • Second Order Division in Sectors As a Prepattern for Sensory Organs in Vertebrate Development Vincent Fleury, Alexis Peaucelle, Anick Abourachid, Olivia Plateau
    Second order division in sectors as a prepattern for sensory organs in vertebrate development Vincent Fleury, Alexis Peaucelle, Anick Abourachid, Olivia Plateau To cite this version: Vincent Fleury, Alexis Peaucelle, Anick Abourachid, Olivia Plateau. Second order division in sectors as a prepattern for sensory organs in vertebrate development. 2021. hal-03098723 HAL Id: hal-03098723 https://hal.archives-ouvertes.fr/hal-03098723 Preprint submitted on 5 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Second order division in sectors as a prepattern for sensory organs in vertebrate development Vincent Fleury1, Alexis Peaucelle2, Anick Abourachid3 and Olivia Plateau1,3,4 1Laboratoire Matière et Systèmes Complexes, UMR 7057 Université de Paris/CNRS, 10 rue Alice Domont et Léonie Duquet, 75013 Paris, France. 2Institut Jean-Pierre Bourgin, UMR 1318 INRA/CNRS INRA Centre de Versailles-Grignon Route de St-Cyr (RD10), 78026 Versailles Cedex, France. 3Laboratoire Mécanismes Adaptatifs et Evolution, UMR 7179 MNHN/CNRS, CP 55, 57 rue Cuvier 75231 Paris cedex 05, France. 4Département de Géosciences, Université de Fribourg, Ch. du Musée 6, 1700 Fribourg, CH Abstract. We describe a general biophysical mechanism underlying sensory organ formation.
    [Show full text]
  • In Early Development of the Rat Mrna for the Major Myelin Protein
    DEVELOPMENTALDYNAMICS222:40–51(2001) InEarlyDevelopmentoftheRatmRNAfortheMajor MyelinProteinP0 IsExpressedinNonsensoryAreasof theEmbryonicInnerEar,Notochord,EntericNervous System,andOlfactoryEnsheathingCells MENG-JENLEE,1 ESTERCALLE,1 ANGELABRENNAN,1 SABRINAAHMED,1 ELENASVIDERSKAYA,2 1 1 KRISTJANR.JESSEN, ANDRHONAMIRSKY * 1DepartmentofAnatomyandDevelopmentalBiology,UniversityCollegeLondon,London,UnitedKingdom 2DepartmentofAnatomy,StGeorge’sHospitalMedicalSchool,London,UnitedKingdom ABSTRACT ThemyelinproteinP0 hasama- INTRODUCTION jorstructuralroleinSchwanncellmyelin,andthe TheP0 geneandthemechanismsthatcontrolithave expressionofP0 proteinandmRNAinthe beenofgreatinteresteversinceitwasrealizedthatP0 Schwanncelllineagehasbeenextensivelydocu- proteinwasbyfarthemostabundantproteinofmyelin mented.Weshowhere,usinginsituhybridization, inthePNS,andthatitsexpressionwassubjectto thattheP0 geneisalsoactivatedinanumberof dramaticregulationbysignalsfromneurons(Gieseet othertissuesduringembryonicdevelopment.P0 al.,1992;LemkeandAxel,1985;SommerandSuter, mRNAisfirstdetectablein10-day-oldembryos 1998).Inmammals,P0 appearedinitiallytobean (E10)andisatthistimeseenonlyincellsinthe exampleparexcellenceofacelltypespecificgene, cephalicneuralcrestandintheoticplacode/pit.P0 beingrestrictedtothoseSchwanncellsinducedtoform expressioncontinuesintheoticvesicleandatE12 myelinsheaths(Colmanetal.,2001).Ithasnowbe- P0 expressioninthisstructurelargelyoverlaps comeclearthattheP0 geneisactivated,albeitatrel- withexpressionofanothermyelingene,proteo- ativelylowlevels,priortomyelinationnotonlyinall
    [Show full text]
  • Prorhombomeric Subdivision of the Mammalian Embryonic Hindbrain: Is It Functionally Meaningful?
    Int..I. Dc\". Riol. -JI; 213-222 (1997) 213 Prorhombomeric subdivision of the mammalian embryonic hindbrain: is it functionally meaningful? ESTHER RUBERTE', HEATHER B. WOOD' and GilLIAN M. MORRISS-KAY' Department of Human Anatomy, Oxford University, Oxford, United Kingdom ABSTRACT The technique of whole embryo culture has made significant contributions to understanding the mechanisms of morphogenesis in mammalian embryos, especially with respect to cranial neurulation and neural crest cell migration. This study traces the fate of two specifically mammalian structures, the preotic and otic sulci. Their formation at the 1/2- and 3-somite stages respectively, divides the hindbrain neuroepithelium into prorhombomeres A, Band C. The preotic sulcus is a deeply recessed structure that forms the rostral boundary of expression of both Hoxb-2and the first domain of Krox-20. The otic sulcus is a shallow concavity in which the second Krox-20domain is expressed, Dillabeling followed by whole embryo culture confirmed that the later fate of the preotic sulcus is the rhombomere 2/3 boundary, and the fate of the otic sulcus is the cranial part of rhombomere 5. Structurally, the preotic and otic sulci show no specialization with respect to actin, tubulin or proteoglycans, buttheir maintenance depends on contact with the subjacent mesenchyme. Their formation is inhibited by exposure of embryos to retinoic acid prior to the onset of somitic segmentation, indicating that the molecular events governing prorhombomeric subdivision of the hindbrain are retinoic acid-sensitive. The preotic sulcus may be essential for neuroepithelial cell movement towards and into the rapidly enlarging forebrain; the otic sulcus may simply delineate the caudal boundary of prorhombomere B, an area with a discrete neural crest cell population discontinuous with those rostral and caudal to it.
    [Show full text]
  • Cardiac Neural Crest Migration in Chicken Embryos
    Dissertation Approved By Major Advisor Philip R. Brauer, Ph.D., Associate Professor of Biomedical Sciences Barbara Braden, Ph.D. MATRIX METALLOPROTEINASE ACTIVITY IS AN IMPORTANT MEDIATOR OF CARDIAC NEURAL CREST CELL MIGRATION By Dong Hong Cai A DISSERTATION Submitted to the Faculty of the Graduate School of Creighton University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Biomedical Sciences Omaha, Nebraska, December, 2001 II This Dissertation Is Dedicated to: My Dear Wife Hong Tao and My Coming Son III Acknowledgments I would like to express my sincere acknowledgment to my major advisor, Dr. Philip R. Brauer, for his guidance, encouragement, and patience throughout all these years. His compassion for science and thirst for knowledge has deeply impressed me. I would like to thank my committee members Dr. John A. Yee, Dr. Robert Mackin, and Dr. Margaret scofield, for their guidance via numerous discussions and for their generosity to let me use their facilities. I would like to thank my former committee member Dr. Thomas M. Vollberg who trained me in molecular biology and generously provided me his lab facilities during my first two years in this department. I would like to thank Dr. James P. Quigley for providing MMP-2 and TIMP-2 cDNA used in this program. 1 would like to thank my parents and my wife for their support and love over the years. Finally, I would like to thank all my friends and colleagues in this department who provided numerous helps whenever help was needed. IV ABSTRACT Matrix metalloproteinases (MMPs) are a family of zinc proteolytic enzymes important in embryonic development and pathological processes.
    [Show full text]
  • Proquest Dissertations
    The Expression and Regulation of the Po Gene During Development of the Rat: Regulation of Basal Level and Early Expression by Meng-Jen Lee Department of Anatomy and Developmental Biology University College London A thesis presented for the degree of Doctor of Philosophy The University of London, 1998 ProQuest Number: U642130 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest U642130 Published by ProQuest LLC(2015). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Acknowledgements I wish to thank Professors Kristjan lessen and Rhona Mirsky for their guidance and enthusiasm throught the course of this work. I also thank Dr. Myrna Dent and Dr. Eric Parmantier for their help and numerous discussions, especially in in situ hybridization technique. I am grateful to Dr. Angela Brennan who contributed to the set up of the neural crest cultures and the study of the regulation of Po protein, and Dr. Ester Calle for contributing to the study of the lineage segregation. I thank Dr Louise Morgan, Dr Helen Stewart and Dr. Ziping Dong for their discussion and help, especially in the early days.
    [Show full text]
  • The Neural Crest and Craniofacial Malformations
    Chapter 5 The Neural Crest and Craniofacial Malformations Hans J.ten Donkelaar and Christl Vermeij-Keers 5.1 Introduction the head (Vermeij-Keers 1990; Sulik 1996; LaBonne and Bronner-Fraser 1999; Le Douarin and Kalcheim The neural crest is a temporary embryonic structure 1999; Sperber 2002; Knecht and Bronner-Fraser 2002; that is composed of a population of multipotent cells Francis-West et al. 2003; Santagati and Rijli 2003). In that delaminate from the ectoderm by epitheliomes- addition, during later developmental stages multiple enchymal tranformation (EMT; Duband et al. 1995; places of EMT are recognized as well. In the head– Hay 1995; Le Douarin and Kalcheim 1999; Francis- neck area, for example, the neurogenic placodes and West et al. 2003). Neural-crest-derived cells are called the optic neural crest are such areas. Neurogenic pla- mesectodermal or ectomesenchymal cells (mesoder- codes, specialized regions of the embryonic ecto- mal cells of ectodermal origin) that have arisen derm, are the major source of primary sensory neu- through EMT. The neural crest was first described rons in the head (Johnston and Bronsky 1995; Gra- by His (1868) in the chick embryo as a Zwischen- ham and Begbie 2000). The vasculature of the head is strang, a strip of cells lying between the dorsal ecto- derived from mesoderm-derived endothelial precur- derm and the neural tube. Classic contributions in sors,while the neural crest provides the pericytes and amphibians identified interactions between tissues smooth muscle cells of the vessels of the face and the that lead to neural crest formation, and were re- forebrain (Etchevers et al.
    [Show full text]