DOCSLIB.ORG

Effect of Local Changes to Shell Permeability on the Gas Exchange of the Avian Embryo

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Effect of Local Changes to Shell Permeability on the Gas Exchange of the Avian Embryo Effect of local changes to shell permeability on the gas exchange of the avian embryo This thesis is presented for the completion of the degree of Doctor of Philosophy by Kerstin Wagner Deparhnent of Environmental Biology The University of Adelaide submitted: October 2000 Table of contents List of tables, plates and figures . ,V Tables..... ,V Plates V Figures VI Abstract.. X Declaration ........ XI Acknowledgment... XI l. lntroduct¡on .1 1.1 Gas exchange of the bird embryo ...... .1 1.2 Diffusionlpertusion inequality............. .3 1.3 Aims. .5 2. General Methods..... .6 2.1 Egg incubation................. .6 2.2 Measuring the conductance of the eggshell .6 2.3 Wax/orygen treatment..... .7 2.4 Waxlhole shell treatment .9 2.4. 1 lntroducing artificial pores .9 2.4.2 Experimental procedure .......... 10 2.5 Experimental groups 12 2.6 Respirometry...... 14 2.6.1 Measurement 14 2.6.2 Analysis of respirometric measurements ...... .. 15 3. Oxygen partial pressure under the eggshell 16 3.1 lntroduction ....... .16 3,2 Material and Methods 18 3.2.1 Components of the gas analysis technique........... .......... 1g 3.2.2 Oxygen partial pressure in the gas spaces of the chicken egg during the second half of incubation .......... .....20 3.2.3 A model for lateral diffusion..... 24 3.3 Resølfs... 26 3.3.1 Oxygen partial pressure in the gas spaces of the chicken egg during the second half of incubation .......... 3.3.1.1 Controleggs 3.3.1.2 Wax/hole eggs 3.3.24 model for lateral diffusion.. 3.3.2.1 Experiment 1 ........ 3.3.2.2 Experiment 2.......... 3.4 Discussíon........ 3.4.1 Oxygen partial pressure in the gas spaces of the chicken egg during the second half of incubation 33 3.4.2 A model for lateral diffusion 34 3.4.3 Formation of an oxygen gradient under war/hole treated eggshell .. 38 3.4.4 Conclusion ....... 41 4. Development of the chorioallantoic membrane......., ..42 4.1 Introduction....... ..42 4.2 Material and Methods ..45 4.2.1 Growth of the chorioallantoic membrane ..46 4.2.2 Density of pre- and post-capillary vessels.... ..48 4.2.3 Blood variables: haemogrobin, haematocrit and blood volume .... .. 50 4.2.3.1 Blood haemoglobin and haematocrit .. 50 4.2.3.2 Blood volume in the chorioattantoic membrane .. 50 4.2.4 Transmission electron microscopic analysis........... ..52 4.2.4.1 Selection and processing of samples........... ..52 4.2.4.2 lmaging... ..52 4.2.4.3 lmage analysis ..53 4.2.4.4 Calculations .... .. 53 4.2.5 Statistical analysis 4.3 Results... 4.3.1 Growth of the chorioallantoic membrane 4.3.2 Density of pre- and post-capillary vessels.... 4.3.3 Blood measurements......... 4.3.3.1 Haemoglobín concentration and haematocrit 4.3.3.2 Blood volume in the chorioattantoic membrane 4.3.4 Capillary density 4.3.5 Morphology of the epithelial layer of the chorioallantois........ 4.3.5.1 lrssue barrier..... 4.3.5.2 Plasma barrier... 4. 3. 5.3 Capillary diameter 4.3.5.4 Thickness of the chorionic epithetium 4.3.6 Capillary blood volume 4.4 Discussion........ .77 4.4.1 CAM growth and attachment .77 4.4.2 Vessel density and blood volume... .79 4.4.2.1 Blood yesse/ density .79 4.4.2.2 Haemoglobin concentration and haematocrit .... .81 4.4.2.3 Blood volume in the chorioattantoic membrane - .83 4.4.3 Capillary morphometry ................ .86 4.4. 3. 1 Barrier thíckness .86 4.4.3.2 Diffusing capacity of the CAM 86 4.4.3.3 Chorionic epithelial thickness. 89 4.4.4 Conclusion ....... 89 5. Embryon¡c growth and respiration ....... .91 5.1 lntroduction....... .91 5.2 Material and Methods .93 5.2.1 Incubation and treatment groups..... .93 5.2.2 Survival rate ......... .94 5.2.3 Data analysis........... .94 5.3 Resulfs .96 5.3. 1 Series A: War/oxygen treatment ............ .96 5.3.1. 1 Embryonic grovvth .96 5.3.1.2 Gas exchange.......... .98 5.3.2 Series B: War/hole treatment - late incubatíon 101 IV 5.3.2.1 Embryonic growth .... ............. 101 5.3.2.2 Gas exchange.......... ............. 106 5.3.3 Series C: lmportance of treatment-timing ............. 114 5.3.3. 1 Embryonic grovvth .............114 5.3.3.2 Gas exchange.......... ............. '117 5.3.4 Survival ............. 120 5.3.5 Location of the aircell...... ............. 122 5.4 Discussíon....... ..... 123 5.4.1 Series A: Effect of the waVoxygen treatment ................... .....123 5.4.2 series B: Effect of wadhole treatment through incubation .....125 5.4.3 comparison of the wan/oxygen and wa¡r/hole treatment... .....127 5.4.4 Series C: lmportance of treatment{iming .....128 5.4.5 Conclusion ............. ..... 130 6. General Summary and Gonclusion........ 132 7. Appendices 137 7.1 Respirometry system... ............. 1g7 7.2 Solutions for fixation and staining .......... ......... 139 7.2.1 Light microscopy - fixation............. ................ 199 7.2.2 Light microscopy - staining ............. 139 7.2.3 Transmission electron microscopy - processing tissue samples ... 140 7.2.4 Transmission electron microscopy - cutting aná staining .......... ... 141 7.2.4.1 Thick secfibns ................ 1,41 7.2.4.2 Thin sections............ 142 7.3 Photometry.... ... 144 7.3.1 Haemoglobin Reagent - Drabkin's solution. ... 144 7.3.2 Model by Lothian (19S8) ... 144 7.4 Relationship between orygen uptake and poz under the shett ... 146 8. Bibliography. 148 V List of tables, plates and figures Tables Tab.2.1'. Fraction of oxygen in the gas mixture for the experimental eggs in war/oxygen treatment....... I Tab.2.2: The number of holes (0.6 mm diameter) per egg drilled into shells in the war/hole treatment depending on the initial shell conductance of the e99...... 10 Tab. 2.3: Overview of experimental groups accord ing to shell treatment, day of experimental man ipulation and day of termination., 12 Tab. 3.1: Treatment groups in analysis of lateral diffusion. 26 Tab.3.2: Comparison of the Po2 averaged under the hole side in wa¡dhole treated eggs with the average Poz calculated from the oxygen consumption of untreated control eggs. 40 Tab.4.1 Haematocrit values as percent of capillary volume in the CAM of day 10 to day 14 chicken e99s........ 76 Tab. 4.2: Diffusing capacity of the CAM.. 88 Tab. 5.1: Water content of embryos in warr/oxygen treatment.. 97 Tab. 5.2: Survival rate in wa/oxygen experiments after shell treatment on day 10, terminated between days 12 and 20..... 120 Tab. 5.3 Survival rate in allwa/hole experiments after treatment on day 10, terminated between days 12to 20... 121 Plates Fig.2A: Diagram of the different treatment groups and controls... 11 Fig. 3A.1: Close-up ímage of the needle electrode inserted through the mercury seal into the glass tube compartment attached to a control e99.......... 21 Fig. 34.2 The position of the electrode was controlled with a micromanipulator outsíde the styrofoam box and inserted through a window at the side........... 21 Fig. 38.1: Positions of glass tubes for the measurement of oxygen partial pressure in undisturbed control e99s........ 23 Fig. 38.2: Positions of glass tubes for the measurement of oxygen partial pressure in eggs with wa¡dhole treatment 23 Fig. 3C: Concentric circles in increments of 0.5 cm radius around a glass compartment........... 25 Fig.3D: Comparison of diffusion path under impermeable shell wíth pore in the model by Ar and Girard (1989) and in the proposed model under a wax-cover........... 35 VI Fig. 4A.1: Gridlines on the eggshell: eight meridians at 45' 47 Fis. 4A.2 47 Fig.48 Standardised Sanson-Flamsteed projection of grid on eggshell (about 70o/o of original size)........ 48 Fig.4C: Contents of a chicken egg on day 8.............. 49 Fig. 4D.1: Cross-section of the CAM at 12S0x.. 49 Fig. 4D.2: lsotropic grid overlayed on chorionic epithelium on day 10, 6200x.. 49 Fig. 4E: Choríonic epithelíum of the 10 d chicken at 6200x........... 70 Fig. 4F.1 Chorionic epithelium of 14 d chicken embryo at 4400x...... 71 Fig. 4F.2: Surface of the chorionic epithelium of ,14 d chicken embryo at 8700x... 71 Fig.4G Surface of the chorionic epithelium of 14 d chicken embryo under wax at 8700x............. 71 Figures Fig.2.1: Increase of oxygen partial pressure in the environment to match the decline of poz under the shell... I Fig. 3.1: Equilibration curves for Poz in glass compartments of two eggs on day 15............ 22 Fig. 3.2: Oxygen partial pressure in the gas space under the shell... 27 Fig. 3.3: Comparison of Poz calculated (from the oxygen consumption and shell conductance) and measured in air cell and equator.... 27 Fig. 3.4 Oxygen partial pressure under the egg shell in in different positions in relation to the wa¡r/hole treatment 28 Fig. 3.5: Effect of the holes in the wax/hole treatment on the oxygen partial pressure under the shell in the equatorial region 29 Fig. 3.6 Oxygen partial pressure on day 1g in the centre of shell covered with wax in circles of increasing radius...... 30 Fig. 3.7: The difference of Poz under the shell between the centre and the margin of wax circles of increasing radius...... 31 Fig. 3.8 Oxygen partial pressure under eggshell without wax cover, and in the centre of a wax circle with 0.5 cm and 1.0 cm radius...... 32 Fig. 3.9: Development of Poz under free shell as calculated from regression curves over wax circles, in comparison to measured values in control eggs..........
Load more

Recommended publications
  • Mechanism of Wound-Healing Activity of Hippophae Rhamnoides L. Leaf Extract in Experimental Burns
    Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2011, Article ID 659705, 9 pages doi:10.1093/ecam/nep189 Original Article Mechanism of Wound-Healing Activity of Hippophae rhamnoides L. Leaf Extract in Experimental Burns Nitin K. Upadhyay,1 Ratan Kumar,1 M. S. Siddiqui,2 and Asheesh Gupta1 1 Defence Institute of Physiology and Allied Science, DRDO, Delhi 110054, India 2 Department of Toxicology, Jamia Hamdard, Delhi 110062, India Correspondence should be addressed to Asheesh Gupta, [email protected] Received 20 July 2009; Accepted 19 October 2009 Copyright © 2011 Nitin K. Upadhyay et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The present investigation was undertaken to evaluate the healing efficacy of lyophilized aqueous leaf extract of Sea buckthorn (Hippophae rhamnoides L., family Elaeagnaceae) (SBT) and to explore its possible mechanism of action on experimental burn wounds in rats. The SBT extract, at various concentrations, was applied topically, twice daily for 7 days. Treatment with silver sulfadiazine (SSD) ointment was used as reference control. The most effective concentration of the extract was found to be 5.0% (w/w) for burn wound healing and this was further used for detailed study. The SBT-treated group showed faster reduction in wound area in comparison with control and SSD-treated groups. The topical application of SBT increased collagen synthesis and stabilization at the wound site, as evidenced by increase in hydroxyproline, hexosamine levels and up-regulated expression of collagen type-III.
    [Show full text]
  • Equine Placenta – Marvelous Organ and a Lethal Weapon
    Equine placenta – marvelous organ and a lethal weapon Malgorzata Pozor, DVM, PhD, Diplomate ACT Introduction Placenta has been defined as: „an apposition between parent (usually maternal) and fetal tissue in order to establish physiological exchange” (1). Another definition of this important organ was proposed by Steven and Morris: „a device consisting of one or more transport epithelia located between fetal and maternal blood supply” (2). The main function of placenta is to provide an interface between the dam and the the fetus and to allow the metabolic exchange of the the nutrients, oxygen and waste material. The maternal circulation is brought into a close apposition to the fetal circulation, while a separation of these two circulatory systems remain separated (3). A degree and complexity of this „intimate relationship” varies greately between species mostly due to the structural diversity of the extraembryonic membranes of the vertebrates. The early feto-maternal exchange in the equine pregnancy is established as early as on day 22 after fertilization. The fetal and choriovitellin circulations are already present, the capsule ruptures and the allantois is already visible (4). The allantois starts expanding by day 32 and vascularizes approximately 90% of the chorion and fuses with it to form chorioallantois by day 38 of gestation (5). The equine placenta continues increasing its complexity till approximately day 150 of gestation. Equids have epitheliochorial placenta, there are six leyers separating maternal and fetal circulation, and there are no erosion of the luminal, maternal epithelium, like in ruminants (6). Thousands of small chorionic microvilli develop and penetrate into endometrial invaginations.
    [Show full text]
  • COMMENTARY the First Evidence of the Tumor-Induced Angiogenesis in Vivo by Using the Chorioallantoic Membrane Assay Dated 1913
    Leukemia (2004) 18, 1350–1351 & 2004 Nature Publishing Group All rights reserved 0887-6924/04 $30.00 www.nature.com/leu COMMENTARY The first evidence of the tumor-induced angiogenesis in vivo by using the chorioallantoic membrane assay dated 1913 Domenico Ribatti1 1Department of Human Anatomy and Histology, University of Bari Medical School, Bari, Italy Leukemia (2004) 18, 1350–1351. doi:10.1038/sj.leu.2403411 tional characterization of the immune system in the chick Published online 17 June 2004 embryo. Early lymphoid cells deriving from the yolk sac and spleen are usually recognizable in the thymus on day 8 and in Virchow, the founder of pathological anatomy, drew attention to the bursa of Fabricius on day 11.6 Thymus cells are present by the huge number of blood vessels in a tumor mass as long ago as day 11 and cell-mediated immunity has been demonstrated by 1865. Tumor vascularization was first studied systematically by day 13–14.7 The chick embryo and the nude mouse are 1 Goldman, who described the vasoproliferative response of the immunological incompetent hosts and do not reject tissues organ in which a tumor develops as follows: ‘The normal blood from a foreign source. Indeed, the chick embryo cannot mount vessels of the organs in which the tumor is developing are an ‘immune’ response to foreign tumor cells until well after day disturbed by chaotic growth, there is a dilatation and spiralling 12, but it can respond to tumor cells by infiltration of monocytes of the affected vessels, marked capillary budding and new vessel and inflammatory-like cells such as avian heterophils.
    [Show full text]
  • Utilisation of Chick Embryo Chorioallantoic Membrane As a Model Platform for Imaging-Navigated Biomedical Research
    cells Review Utilisation of Chick Embryo Chorioallantoic Membrane as a Model Platform for Imaging-Navigated Biomedical Research Lei Chen 1 , Shuncong Wang 1 , Yuanbo Feng 1, Jinyong Zhang 2,3, Yuqing Du 2, Jiang Zhang 4, Chantal Van Ongeval 1, Yicheng Ni 1,* and Yue Li 2,* 1 KU Leuven, Biomedical Group, Campus Gasthuisberg, 3000 Leuven, Belgium; [email protected] (L.C.); [email protected] (S.W.); [email protected] (Y.F.); [email protected] (C.V.O.) 2 Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai 201318, China; [email protected] (J.Z.); [email protected] (Y.D.) 3 School of Medical Instrument and Food Engineering, University of Shanghai for Science & Technology, Shanghai 200093, China 4 Faculty of Agricultural Biotechnology and Ecotechnology, Shanghai Vocational College of Agriculture and Forestry, Shanghai 201600, China; [email protected] * Correspondence: [email protected] (Y.N.); [email protected] (Y.L.) Abstract: The fertilised chick egg and particularly its chorioallantoic membrane (CAM) have drawn continuing interest in biomedicine and bioengineering fields, especially for research on vascular study, cancer, drug screening and development, cell factors, stem cells, etc. This literature review sys- temically introduces the CAM’s structural evolution, functions, vascular features and the circulation system, and cell regulatory factors. It also presents the major and updated applications of the CAM in assays for pharmacokinetics and biodistribution, drug efficacy and toxicology testing/screening in preclinical pharmacological research. The time course of CAM applications for different assays Citation: Chen, L.; Wang, S.; Feng, Y.; and their advantages and limitations are summarised.
    [Show full text]
  • 1 the Evolution of Endocrine
    THE EVOLUTION OF ENDOCRINE EXTRAEMBRYONIC MEMBRANES; A COMPARATIVE STUDY OF STEROIDOGENESIS AND STEROID SIGNALING IN THE CHORIOALLANTOIC MEMBRANE OF OVIPAROUS AMNIOTES By LORI CRUZE ALBERGOTTI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2011 1 © 2011 Lori Cruze Albergotti 2 Ken, I will be forever grateful for your love and support. 3 ACKNOWLEDGMENTS First, I would like to thank Lou Guillette for his generous financial, technical and emotional support. Lou has taught me that being a scientist is the opportunity to be a detective in pursuit of answers to an intriguing question, and this pursuit requires not only an analytical mind, but also a creative one. I thank Lou for giving me this opportunity and for his endless guidance and encouragement, and last but not least for his friendship. I could not have asked for a better graduate experience and I am convinced that this has everything to do with having Lou as an advisor and Bernie, Colette, Marty and Malcolm as committee members. I would like to thank Bernie for pushing me outside of my comfort zone, for encouraging me to think broadly about my research, and for his willingness to provide lab assistance. Thank you to Colette for lending statistical and experimental design expertise, for pushing me to think about the big picture of my research, and for always believing in me. I would like to thank Marty for expanding my understanding of evolution and development, for allowing me the amazing opportunity to teach with him, and for making his lab available to me.
    [Show full text]
  • The Use of the Chorioallantoic Membrane of the Developing Chick
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector THE USE OF THE CHORIOALLANTOIC MEMBRANE OF THE DEVELOPING CHICK FOR CULTURE OF DERMATOPHYTES—A MODIFIED TECHNIC A PRELIMINARY REPORT UPON ITS USE FOR SERIAL PASSAGE* BETTY M. PARTRIDGE, M.A. The chorioallantoic membrane of the develop-downy and granular strains in culture is T. men- ing chick embryo provides a suitable living sub-tagrophytes. A conversion of these downy forms strate for the cultivation of pathogenic fungi.into granular forms, during the course of serial This was first demonstrated by Moore (1) inpassage in guinea-pigs, was observed by Georg a histo-pathological study using a variety of(4). As the growth and production of lesions on fungi, including four dermatophytes: Micro-the chorioallantoic membrane by dermato- sporum canis, Epidermophyton floccosum (E.phytes was known, from earlier workers, to be inguinale), Trichophyton mentagrophytes(T. rapid compared with other laboratory animals, gypseum) and T. schoenleini (Achorion Schoen-it was decided to investigate the use of this leini). More recently, Showalter (2) studiedtechnic as a method for passage of cultures. By the morphological changes of the first threethe serial passage of T. rubrum from one chick dermatophytes, listed above, when in contactembryo membrane to another, it was hoped to with the living chick membrane. determine whether there was correlation between The object of the investigation, describedstrains and any alteration in their morphology in the present paper, was primarily to developand pathogenicity after passage. an improved in vivo technic for cultivating dermatophytes in the chorioallantois, and to METHODS AND MATERIALS compare the results so obtained with those of The cultivation technic employed by Moore previous workers.
    [Show full text]
  • Specialised Cell Types in the Chickembryo Chorioallantoic
    J. Anat. (1995) 186, pp. 245-252, with 10 figures Printed in Great Britain 245 Ultrastructural and immunocytochemical evidence for the presence of polarised plasma membrane H+-ATPase in two specialised cell types in the chick embryo chorioallantoic membrane ROBERTO NARBAITZ', BAHAR BASTANI2, NANCY J. GALVIN3, VIJAY K. KAPAL' AND DAVID Z. LEVINE4 (with the technical assistance of Liying Yang2) Departments of' Anatomy and Neurobiology and4 Medicine, University of Ottawa, Canada, and 2Division of Nephrology and 3 Department of Anatomy, St Louis University, St Louis, Missouri, USA (Accepted 12 September 1994) ABSTRACT The chick embryo, confined in the eggshell, has to dispose/buffer the acid generated by its metabolism, as well as to release calcium from the shell which is used for growth. To localise H+-ATPase, electron microscope and immunocytochemical studies were conducted on chorioallantoic membranes of 15-17 d chick embryos. Ultrastructural studies of the villus cavity (VC) cells in the chorionic epithelium demonstrated that their apical plasma membrane, juxtaposed with the shell membranes, contains microvilli as well as microplicae which possess 9-10 nm studs at a density of 16700 particles/gMm2, a characteristic feature of the polarised H+-ATPase pump. Immunocytochemical staining, using a monoclonal antibody to the 31 kDa subunit of H+-ATPase, confirmed the presence of large amounts of the vacuolar H+-ATPase in the VC shells with a distribution highly polarised towards the eggshell membranes. Immunoelectron- microscopic localisation studies using a rabbit antiserum to whole bovine H+-ATPase and immunogold technique, confirmed the localisation of H+-ATPase at the apical microvilli/microplicae as well as in the subapical vesicles.
    [Show full text]
  • Dynamics of the Developing Chick Chorioallantoic Membrane
    RESEARCH ARTICLE Dynamics of the Developing Chick Chorioallantoic Membrane Assessed by Stereology, Allometry, Immunohistochemistry and Molecular Analysis Andrew Ndegwa Makanya1*, Ivanka Dimova2, Tobias Koller3, Beata Styp-Rekowska3, Valentin Djonov3 a11111 1 Department of Veterinary Anatomy and Physiology, Riverside Drive, Chiromo Campus, University of Nairobi, Box 30197, 00100, Nairobi, Kenya, 2 Department of Medical Genetics, Medical University Sofia, Zdrave street 2, 1431, Sofia, Bulgaria, 3 Institute of Anatomy, University of Bern, Baltzerstrasse 2 CH-3000, Berne, 9, Switzerland * [email protected] OPEN ACCESS Abstract Citation: Makanya AN, Dimova I, Koller T, Styp- Rekowska B, Djonov V (2016) Dynamics of the The chick chorioallantoic membrane (CAM) is a widely used model for the study of angio- Developing Chick Chorioallantoic Membrane genesis, tumour growth, as well as drug efficacy. In spite of this, little is known about the Assessed by Stereology, Allometry, developmental alteration from its appearance to the time of hatching. In the current study Immunohistochemistry and Molecular Analysis. PLoS the CAM has been studied by classical stereology and allometry. Expression levels of ONE 11(4): e0152821. doi:10.1371/journal. pone.0152821 selected angiogenesis-related molecules were estimated by RT-PCR and cell dynamics assessed by proliferation and apoptosis assays. Absolute CAM volume increased from a Editor: Domenico Ribatti, University of Bari Medical 3 3 School, ITALY low of 0.47 ± 0.11 cm at embryonic day 8 (E8) to a high of 2.05 ± 0.27 cm at E18, and then decreased to 1.6 ± 0.47 cm3 at E20. On allometric analysis, three growth phases were iden- Received: February 8, 2016 | downloaded: 4.10.2021 tifiable.
    [Show full text]
  • The Extracellular Matrix and VEGF Processing
    5 The Extracellular Matrix and VEGF Processing Sunyoung Lee, PhD, and M. Luisa Iruela-Arispe, PhD Summary Tumor neovascularization requires the activation of a subset of endothelial cells from normal vascular beds, the digestion of the underlying basement membrane, and the directional migration of these cells toward an avascular site. The contri- bution of vascular endothelial growth factor (VEGF) to each one of these steps has received large experimental support, and it has been demonstrated that pharmaco- logical and/or genetic inactivation of this growth factor can impact the angiogenic response and consequently suppress tumor growth. Thus, understanding the mecha- nisms that control VEGF levels has become an important focus of investigation. Today, we have a fairly comprehensive understanding of the mechanisms that regulate VEGF transcriptional rate and half-life. In contrast, little emphasis has been placed on the regulation of VEGF biology post-secretion. In this chapter, we focus our attention on the question of how VEGF becomes released from the extracellular environment and contributes to tumor neovascularization. We discuss this point in the larger context of matrix interaction with growth factors and their modulation by matrix metalloproteinases (MMPs). Key Words: Matrix metalloproteinases; growth factors; angiogenesis; tumor microenvironment; endothelial cells; capillaries; neovascularization. 1. INTRODUCTION It is generally accepted that the tissue/tumor microenvironment plays an active role in regulating the angiogenic response. Matrix molecules serve as substrate for migration of endothelial cells, as well as provide differentiation cues for the maturation and stabilization of new vascular beds (1–3). Thus, the nature and physical features of the extracellular environment can provide differential permissive signals for angiogenesis progression and stabilization.
    [Show full text]
  • Clade Amniota
    Lab exercise 19: Reptiles, Birds, and Mammals Clade Amniota This taxon represents a monophyletic group including the mammals, reptiles, birds, and their extinct relatives. Specifically, it includes the most recent common ancestor of mammals and reptiles and all descendants of that ancestor (Gauthier et al., 1988). There are many synapomorphies in this group that are noted as characteristics related to a terrestrial lifestyle. The most notable of these features is the amniotic egg, for which the group is named. The various structures associated with the amniotic egg are allow the egg to be laid on dry land, and serve to protect and nourish the developing embryo. The amniotic egg The outermost layer of the egg of amniotes is the shell, which is either soft and leathery or hard and mineralized. The hard egg is a synapomorphy of archosaurs (a group which includes crocodiles and birds) while other reptiles possess a softer, less mineralized, leathery shell (Laurin and Gauthier, 1996). The earliest amniotes most likely had a much less 4 mineralized shell; as a result, these eggs are poorly represented in the fossil record (Laurin, Reisz & Girondot, 2000). The shell is a structure that protects the egg not 3 from dessication, but from abrasion and friction associated with the pull of gravity coupled with the dry surface on which 2 the egg has been laid. The nutritional, water, and waste removal requirements of the embryo are met by a series of four 2 1 membranes: the chorion, amnion, yolk sac, and allantois. The outermost layer (within the shell) is the chorion [1].
    [Show full text]
  • Tracking Modified Vaccinia Virus Ankara in the Chicken Embryo
    viruses Article Tracking Modified Vaccinia Virus Ankara in the Chicken Embryo: In Vivo Tropism and Pathogenesis of Egg Infections Martin C. Langenmayer 1,2 ID , Anna-Theresa Lülf-Averhoff 1, Silvia Adam-Neumair 1, Gerd Sutter 1,2,* and Asisa Volz 1,2 1 Institute for Infectious Diseases and Zoonoses, LMU Munich, 80539 Munich, Germany; [email protected] (M.C.L.); [email protected] (A.-T.L.-A.); [email protected] (S.A.-N.); [email protected] (A.V.) 2 German Center for Infection Research (DZIF), Partner Site Munich, 80539 Munich, Germany * Correspondence: [email protected]; Tel.: +49-89-2180-2514 Received: 2 August 2018; Accepted: 21 August 2018; Published: 24 August 2018 Abstract: The Modified Vaccinia virus Ankara (MVA) is a highly attenuated vaccinia virus serving as a promising vector vaccine platform to develop vaccines against infectious diseases. In contrast to the well-established replication deficiency and safety of MVA in mammals, much less is known about MVA infection in avian hosts. Here, we used a recombinant MVA expressing fluorescent reporter proteins under transcriptional control of specific viral early and late promoters to study in vivo tropism, distribution, and pathogenesis of MVA infections in embryonated chicken eggs. The chorioallantoic membrane (CAM) of embryonated chicken eggs was inoculated with recombinant MVA, MVA or phosphate-buffered saline. The infection was analyzed by fluorescence microscopy, histology, immunohistochemistry, and virus titration of embryonic tissues. After infection of the CAM, MVA spread to internal and external embryonic tissues with the liver as a major target organ.
    [Show full text]
  • Application of the Chick Embryo Chorioallantoic Membrane in Neurosurgery Disease Yong-Jie Yuan*, Kan Xu*, Wei Wu, Qi Luo, and Jin-Lu Yu
    Int. J. Med. Sci. 2014, Vol. 11 1275 Ivyspring International Publisher International Journal of Medical Sciences 2014; 11(12): 1275-1281. doi: 10.7150/ijms.10443 Review Application of the Chick Embryo Chorioallantoic Membrane in Neurosurgery Disease Yong-Jie Yuan*, Kan Xu*, Wei Wu, Qi Luo, and Jin-Lu Yu Department of Neurosurgery, Jilin University First Hospital, Changchun 130021, China. * These authors contributed equally to this work. Corresponding authors: Jin-Lu Yu and Qi Luo, Department of Neurosurgery, Jilin University First Hospital, Changchun 130021, China. Tel: +86-431-88782264 Email: [email protected]. © Ivyspring International Publisher. This is an open-access article distributed under the terms of the Creative Commons License (http://creativecommons.org/ licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. Received: 2014.08.30; Accepted: 2014.10.13; Published: 2014.10.27 Abstract The chick embryo chorioallantoic membrane (CAM) is a highly vascularized extraembryonic membrane. Because of its ease of accessibility, extensive vascularization and immunodeficient environment, the CAM has been broadly used in the oncology, biology, pharmacy, and tissue regeneration research. The present review summarizes the application of the CAM in neuro- surgery disease research. We focused on the use of the CAM as an assay for the research of glioma, vascular anomalies, Moyamoya Disease, and the blood-brain barrier. Key words: chorioallantoic membrane, glioma, vascular disease, blood brain barrier. Introduction The chick embryo chorioallantoic membrane 26], the mechanisms of wound healing [27, 28], and the (CAM) is an extraembryonic membrane.
    [Show full text]