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Chapter 9 Flashcards CHICK

Rosheen Villaraza Biology Inglés 141 fichas

Chapter 9 Flashcards CHICK

Fichas del conjunto (141)

  1. 1What are the two advantages to using chick as a model organism?1. They are amniotes; they have similar morphological development to mammals
    2. Embryogenesis occurs externally, i.e., outside the mother
  2. 2Why is the chick considered to be a bad genetic system?1. There is no routine protocol for transgenesis or targeted mutagenesis
    2. Any that exist are impractical and are labor intensive
  3. 3Even though chick has "bad genetics," there are some experiments you CAN run. Name TWO and how they work.1. Genes can be overexpressed using RCA viruses; viruses containing the gene of interest infect the cell and overexpress the gene
    2. An induction study can be run where affinity chromatography beads containing growth factors mimic signaling centers and are implanted into different regions of the embryo
  4. 4When does oogenesis occur in chick?During fetal life
  5. 5TRUE OR FALSE: (Provide a correct statement if false) Oogonia continue dividing throughout adult life.FALSE.
    Oogonia stop dividing before birth, like in mammals
  6. 6The yolk corresponds to the _________ oocyte.mature
  7. 7What happens at around 24 hours to the mature oocyte? Under what assumption?The mature oocyte moves down the oviduct and becomes fertilized, assuming mating has occurred.
  8. 8Where on the oocyte does fertilization occur?At the blastodisc
  9. 9What is the blastodisc?The blastodisc is the embryo-forming portion of the egg appearing as a small disc on the upper surface of the yolk mass
  10. 10What FIVE things occur when the oocyte passes down the oviduct?1. It is fertilized
    2. The albumin layer is added
    3. The shell membranes are added
    4. The shell is added
    5. The egg undergoes oviposition
  11. 11What is the albumin layer in layman's terms?The egg white
  12. 12What is oviposition?Oviposition means the egg is laid
  13. 13After fertilization, the blastodisc is referred to as the ______________.blastoderm
  14. 141. How are the early embryogenesis stages labeled? 2. Which stage numbers correspond to early embryogenesis? 3. Where do the early embryogenesis stages occur?1. With Roman Numerals
    2. Stages I - X
    3. In the oviduct
  15. 151. What sort of cleavage is exhibited in chick? 2. Where does cleavage occur?1. (Extreme) Meroblastic cleavage
    2. In the blastodisc
  16. 16At Stage V, the blastoderm consists of a few hundred cells. What happens to the blastoderm at Stage V?A space opens up between the blastoderm and the yolk called the subgerminal cavity
  17. 17Once the subgerminal cavity is formed, the blastoderm can be visually categorized into three zones. 1. What are these three zones called? 2. Which cells participate in each zone?1. The area pellucida, the area opaca, and the marginal zone.
    2. The cells not touching the yolk are the area pellucida; they are transluscent
    The area of the blastoderm that are still in contact with the yolk are is the area opaca; they are opaque
    The marginal zone is the junction of the area pellucida and the area opaca
  18. 18What is the primary hypoblast? How is the primary hypoblast formed? At what stage does this happen?At Stage X, cells delaminate from the blastoderm into the subgerminal cavity to form ingressions of small groups of cells called the primary hypoblast
  19. 19TRUE OR FALSE: (Provide a correct statement if false) The secondary hypoblast is the presumptive epiblastFALSE.
    The PRIMARY hypoblast is the presumptive epiblast
  20. 201. What forms after the primary hypoblast? 2. Where does it come from? 3. What is the top layer is now known as?1. The secondary hypoblast
    2. It comes from the posterior marginal zone
    3. The epiblast
  21. 211. When do we start using the Hamburger and Hamilton staging method? 2. How is it different from the other staging method?1. Before egg laying, roman numerals are used to label early embryonic stages. AFTER egg laying, we adopt H&H staging.
    2. H&H staging uses arabic numerals instead of Roman numerals
  22. 22When does gastrulation begin?Shortly after egg laying
  23. 23The formation of which structure promotes gastrulation?The primitive streak
  24. 24From what region does gastrulation start?The posterior marginal zone
  25. 25What happens at Stage 2 in the developing chick?A condensation of cells called the primitive streak emerges from the posterior edge of the area pellucida and elongates toward the anterior end of the embryo.
  26. 26By Stage 4 in the developing chick, what happens to the epiblast cells close to the primitive streak? What are their fates?Some epiblast cells will delaminate through the primitive streak; these will become mesoderm and endoderm.
    The epiblast cells that do not enter the primitive streak will become ectoderm.
  27. 271. What is the leading edge of the primitive streak called? 2. What does it do? 3. What is expressed there?1. Hensen's node
    2. Hensen's node is analogous to Spemann's organizer; it will eventually form the notochord.
    3. Goosecoid and Brachyury
  28. 281. What happens to Hensen's node by Stage 6? 2. What does this event initiate?1. By Stage 6, Hensen's node regresses
    2. Once it regresses, it forms the notochord in its wake
  29. 29What has formed by Stage 7?The notochord
  30. 30What transcription factor is expressed in the primitive streak?Brachyury
  31. 31During gastrulation, what happens to the original hypoblast and endoblast cells?They are pushed to the outer rim. This is how they become extraembryonic.
  32. 32What takes the place of the ejected hypoblast and endoblast cells?Endoderm cells
  33. 33Describe neurulation in the chick. (4 general points)1. Once axial mesoderm is established, it becomes the notochord
    2. Overlying ectoderm receives a signal from the notochord to become the neural plate
    3. Neural folds rise and meet at the dorsal midline and form the neural tube
    4. Ectoderm becomes epidermis
  34. 341. What does para-axial mesoderm form? 2. What does intermediate mesoderm form?1. Somites
    2. Kidneys, gonads, and adrenals
  35. 35What is unique about the lateral plate mesoderm in chick?The lateral plate mesoderm is divided into two layers: the somatic layer and the splanchnic layer.
  36. 361. Regionally speaking, what is the difference between the somatic layer and the splanchnic layer? 2. What is the space between them called?1. The somatic layer adheres to the epidermis
    The splanchnic layer adheres to the endoderm
    2. The space in between is the coelom
  37. 371. What will the somatic lateral plate mesoderm eventually become? 2. What will the splanchnic lateral plate mesoderm eventually become?1. The somatic layer will become the body wall
    2. The splanchnic layer will form the musculature that surrounds the gut
  38. 38TRUE OR FALSE: (Provide a correct statement if false) Epiblast are cells that have not yet been determined.TRUE
  39. 391. When labeled with DiI or DiO, what sorts of movements can be seen by epiblast cells in Stage 3? 2. What are these movements key for?1. Polonaise movements
    2. Polonaise movements are key for the formation of the primitive streak
  40. 401. Describe the trajectory of polonaise movements. 2. What do polonaise movements depend on?1. Cells exhibiting polonaise movements swirl posteriorly then move to the anterior
    2. Polonaise movements depend on the wnt pathway
  41. 41Instead of dorsal ventral, like in a blastula, what terms are used for blastoderm? Which term corresponds to dorsal and ventral, respectively?Medial-Lateral
    medial = dorsal
    lateral = ventral    Instead of dorsal ventral, like in a blastula, what terms are used for blastoderm? Which term corresponds to dorsal and ventral, respecti...
  42. 42After the three germ layers are established, the body is sculpted through a process called _______________.body folding
  43. 43What happens to the anterior end of the embryo after one day of incubation?The anterior end of the embryo is marked by an uplifting of the blastoderm called the head fold
  44. 441. How are the foregut and hindgut formed? 2. How is the midgut formed? What is it connected to?1. A fold near the anterior forms the foregut. An analogous fold near the posterior forms the hindgut.
    2. These folds will continue to form and merge together to form the midgut. The midgut will be connected to the yolk for the most part of embryogenesis
  45. 45Around Day 3, what happens with the outer area opaca?The outer area opaca expands over the surface of the yolk as a membrane consisting of extraembryonic ectoderm and endoderm
  46. 461. What begins to form and extend by the third day? 2. What is the result of this process?1. A fold at the anterior extraembryonic region starts to extend and cover the anterior end of the embryo. A corresponding fold grows from the posterior.
    2. The folds fuse at the middle to form two complete membranes covering the embryo
  47. 471. What are the two main membranes that encase the developing embryo? 2. What kind of cavities do they form? 3. Which is the outer membrane? the inner membrane?1. The amnion and the chorion
    2. The amnion forms the amniotic cavity which immediately surrounds the embryo
    The chorion encompasses the embryo and the underlying yolk
    2. Outer membrane = chorion
    Inner membrane = amnion
  48. 48What germ layers make up the chorion and amnion?somatic mesoderm and ectoderm
  49. 49What germ layers encase the yolk sac?splanchnic mesoderm and endoderm
  50. 50What forms the allantois? What is it connected to?The allantois is formed by splanchnic mesoderm and endoderm which is connected to the gut
  51. 51What two functions are served by the allantois?1. It is an excretory receptacle
    2. Serves as a respiratory organ; oxygen can enter through the allantois
  52. 52How does the allantois excrete waste from metabolic processes?The allantois grows out from the hindgut into the extraembryonic coelom and fuses with the undersurface of the chorion. This is called the chorioallantoic membrane.
  53. 53EARLY FATE MAPS 1. Where does the prospective head lie at Stage X? 2. Where do the prospective posterior and lateral regions lie?1. The prospective head lies in the posterior
    2. The prospective posterior and lateral regions lie more anterior
  54. 54What induces presumptive mesoderm? From where?Vg1 is expressed in the posterior marginal zone. It induces presumptive mesoderm which is all in the primitive streak.
  55. 55At Stage X, prospective head is in the posterior, and prospective posterior and lateral regions are more anterior. How is this initial configuration inverted by Stage 3?Polonaise movements followed by lateral invagination of cells through the primitive streak puts mesodermal cells in a different position later on in development; during the actual formation and movement of the primitive streak
  56. 561. What is the prospective region for the notochord? Where? 2. Through what event does this happen?1. The node itself is the prospective region for the notochord along the entire length of the body
    2. This occurs during node regression
  57. 57Experiments that label mesodermal cells located near the anterior portion of the primitive streak with DiO (green) will form WHAT and WHERE?Mesodermal cells located near the anterior portion of the primitive streak will form axial mesoderm at the medial side of the embryoExperiments that label mesodermal cells located near the anterior portion of the primitive streak with DiO (green) will form WHAT and WHERE?
  58. 58Experiments that label mesodermal cells located near the posterior portion of the primitive streak with DiI (red) will form WHAT and WHERE?Mesodermal cells located near the posterior portion of the primitive streak will form lateral mesoderm at the lateral side of the embryoExperiments that label mesodermal cells located near the posterior portion of the primitive streak with DiI (red) will form WHAT and WHERE?
  59. 59Mesodermal cells located near the center of the primitive streak will form WHAT?Intermediate mesoderm
  60. 60What sorts of tissues will become of the posterior part of the primitive streak?extraembryonic tissues
  61. 61Endoderm underlying the mesoderm is in alignment with it and receives the same kind of signaling. What is the result of this?The underlying endoderm will also form a gradient that elicits different types of endoderm
  62. 62Why do we see expression of vg1 in the primitive streak at Stage 3?Cells in the primitive streak will delaminate through to become mesoderm or endoderm, which is why we can see expression of vg1 in the primitive streak at Stage 3 because vg1 is expressed in endoderm.
  63. 63Two experiments demonstrate the power of the posterior marginal zone to induce the primitive streak. 1. Describe both experiments and the results of each 2. What is not present in both of these experiments? (hint: it has been removed)1a) Take a graft of the posterior marginal zone and transplant to the anterior epiblast of another embryo.
    A primitive streak is induced at the anterior zone.
    1b) Soak affinity chromatography beads with vg1- and wnt1-secreting pellets and introduce them to an anterior epiblast of an embryo
    A primitive streak is induced at the anterior zone.
    2. In both of these experiments, the marginal zone has been removed
  64. 64What is a good way to test to see if something is actually a primitive streak?To check to see if a true primitive streak has been formed, test for expression of brachyury
  65. 651. Where is wnt1 found? 2. What does it do?1. In the marginal zone
    2. It aids vg1 to form the primitive streak
  66. 661. What will happen if vg1-secreting pellets were implanted in an embryo still containing a marginal zone? 2. What happens when stained for Brachyury? 3. What happens when stained for goosecoid? 4. How is induction possible?1. Another primitive streak will form
    2. Staining for Brachyury will show two streaks
    3. Staining for goosecoid will show expression at the two nodes
    4. Induction is possible because wnt1 is present
  67. 671. What would happen if a donor node were grafted into the more lateral part of a host embryo? 2. Although only the node was grafted, the neural tube and somites are induced. How is this possible?1. It will form an ectopic axis
    2. They are derived from the host, not the graft. The notochord is inducing the ectoderm to become neural tube and para-axial mesoderm to become somites
  68. 68Where is BMP expressed?It is expressed in the more lateral regions but converges in the more posterior regions
  69. 69What is expressed near the medialanterior region where BMP is not expressed?Chordin and Noggin
  70. 70What are we sure to find wherever BMP is expressed?Phosphorylated SMAD1
  71. 711. BMP inhibitors do not have neurulizing activity when introduced to explants of _____________(1). 2. What does this suggest?1. epiblast
    2. Likely more factors are required for neurulation
  72. 72If BMP is artificially introduced into the embryo, what is suppressed and what is promoted?Somite formation is suppressed and lateral plate induction is promoted
  73. 73What happens when noggin is artificially introduced into lateral tissue?Ectopic somites are induced
  74. 74What do experiments involving the artificially introduction of BMP and noggin demonstrate?Medial-Lateral patterning depends on graded inhibition of BMP activity
  75. 75TRUE OR FALSE: (Provide a correct statement if false) The chick is truly bilateral.FALSE.
    The chick exhibits left-right asymmetry
  76. 76Generally outline the process of establishing Left-Right Asymmetry (4 general steps)1. Breakage of basic bilateral symmetry in the node or midline structure
    2. Amplification of the initial asymmetry to create different domains of gene expression on either side of the midline
    3. A spread of the information out to the lateral mesoderm, which is the tissue layer most involved in the formation of the asymmetrical organs
    4. Control of cell adhesion and movement events that actually bring about the asymmetrical morphology
  77. 77How is asymmetry influenced in xenopus, zebrafish, and mouse?Asymmetry is influenced by the leftward movement of cilia on the node-related structure
  78. 78TRUE OR FALSE: (Provide a correct statement if false) Cilia play an integral role in establishment of asymmetry in chick developmentFALSE.
    Cilia do not seem to have a role in asymmetry for chick
  79. 79Broadly explain how is asymmetry is generated for chick. (Hint: do not include any molecules in your answer. Think about the membrane potential)Asymmetry is generated by a depolarization of membrane potential on the left side of the streak
  80. 801. The change in membrane potential involves activity of __________(1). 2. Describe the process and what the end result is1. H+/K+ - ATPase
    2. Ions are pumped through the membrane and depolarizes the membrane with respect to the other side; this translates into differential gene expression
  81. 81In establishment of left-right asymmetry, which molecules will be found on the left? Which molecules will be found on the right?LEFT: Sonic Hedgehog (SHH) and Nodal
    RIGHT: Activin, Fibroblast Growth Factor (FGF), and Sonic Hedgehog
  82. 82What does SHH do?activates NODAL
  83. 83What does NODAL do?promotes leftness
  84. 84What do activins do?activate FGF's
  85. 85What does FGF do?Inhibits SHH
  86. 86If activin is artificially expressed on the left, what would happen? What is the final result?SHH would be inhibited. There would be no symmetry breaking. The final result would be randomization.
  87. 87If SHH is artificially expressed on the right, what would happen? What is the final result?There would be no breaking of symmetry. The final result would be randomization.
  88. 88Amplification of initial asymmetry creates different domains of gene expression on either side of the midline during the left-right asymmetry process. How/when does this occur?This occurs as the node is regressing forming the notochord
  89. 89Explain the bistable switch system with regards to nodal.SHH is the activator of nodal. Nodal's protein product has the ability to build up its own concentration. When neither SHH or Nodal protein product is present, the system is "off."
  90. 90TOUGHIE Describe the pathway that controls cell differentiation on the left side of the embryo. (6 general points)1. SHH activates nodal
    2. Nodal activates Caronte
    3. BMP is found on the lateral regions of the left and right sides but is inhibited by Caronte on the left side
    4. In the presence of Caronte, Nodal is free to continute amplifying on the left side, overwhelming the system and inhibiting BMP
    5. Snail-related factor (SNR) turns off PITX2, Nodal turns off snail-related factor (SNR). By inhibiting SNR, nodal essentially turns on PITX2
    6. PITX2 controls cell differentiation on the left side of the embryo
  91. 91What would happen is nodal is experimentally expressed on the right side?Randomization of left-right asymmetry
  92. 92What would happen if SHH were activated on the right side?SHH would upregulated nodal expression
  93. 931. What would happen if Activin or FGF were applied to the left side? 2. What does this suggest about their positions in the pathway?1. Activin or FGF would repress nodal
    2. This suggests they are upstream regulatory components
  94. 94Which organ system is the first to form?The central nervous system
  95. 95How long is the ovulation to egg-laying period?24 hours
  96. 96What THREE events happen 24 hours after egg-laying (48 hours post ovulation)?1. The head fold forms
    2. Neurulation initiates in the anterior
    3. Somites start to form
  97. 97Which particular germ layer does the dermis arise from?Para-axial mesoderm
  98. 98When does the heart begin to form?Between 24 and 33 hours
  99. 99Why is it important for the circulatory system to develop as soon as possible?The growing embryo needs to deliver oxygen to its metabolizing cells
  100. 10033 hours after egg-laying, what structures can be seen? (2 general points)1. Three major subdivisions of the brain are visible: The forebrain, midbrain and hindbrain.
    2. The heart is bent slightly to the right as the circulatory system matures
  101. 101What is established by hour 36?By the 36th hour, the general body system has been laid down.
  102. 102What alternative is there to identify different stages in chick? (Hint: it's an internal control for staging)The number of somites can be used as a staging method. For example, a chick at the "9 somite stage"
  103. 103What happens early on the second day (33 hours)? (2 general points)1. Blood islands appear in the outer extraembryonic part of the blastoderm
    2. The heart primordium forms by fusion of the rudiments on the right and left side of the anterior mesoderm    What happens early on the second day (33 hours)? (2 general points)
  104. 104Where and how does the heart originate?The heart originates at the hindbrain level as two endothelial tubes.
    It is formed by cavitation
  105. 105The endocardial tubes are ___________ in nature.endothelial
  106. 106What is the endothelium?The endothelium is epithelial cells that are specific to the inner lining of vasculature structures such as blood vessels and capillaries, which are derived from cardiac mesoderm
  107. 107Mesenchymal cells are migratory cells. How does epithelium move?Epithelium moves though invagination and involution
  108. 108What are the endocardial tubes surrounded by?mesenchymal splanchnic mesoderm
  109. 109How does the myocardium form?Migrating splanchnic mesoderm fuses around the endocardial tubes forming the myocardium
  110. 110What is the pharynx?The pharynx is the most anterior part of the gut
  111. 111TOUGHIE Outline the formation of the heart, using stages when possible. (4 detailed points)1. During inversion of configuration, rogue mesenchymal cardiac mesoderm migrate up to the anterior region near the hindbrain and form two cords that hollow out by cavitation, called endocardial tubes.
    2. By Stage 7-8, splanchnic mesoderm migrates to surround the endocardial tubes and fuses to form the myocardium, forming the outer part of the primitive heart (now the primitive heart is more ventral to the pharynx).
    3. By stage 10, the endocardial tubes, close in proximity, fuse and the heart becomes one tube
    4. Once fused, it begins to regress posteriorly, following the progression of the anterior body fold
  112. 1121. The neural crest is sometimes nicknamed _______________________(1). 2. What will a small subset of neural crest cells form in relation to the heart?1. The fourth germ layer
    2. A small subset of neural crest cells will form a small part of the outflow tract of the heart
  113. 113Outline the general steps in the development of the early circulatory system. (4 general points)1. Blood islands and blood vessels appear in the area opaca
    2. The vessels grow into the area pellucida joining with vessels arising from the mesoderm within the embryo
    3. The heart starts to beat around 33 hours
    4. Blood circulation between the embryo and the yolk mass is established by the third day
  114. 114What happens to the vasculature soon after blood circulation is established between the embryo and the yolk mass?The vasculature will be routed to the allantois to get rid of waste products
  115. 115What vasculature imports oxygenated blood into the heart?Vitelline veins
  116. 116By 48 hours, what structures make up the heart (from posterior to anterior)? (4 items)1. Sinus venosus
    2. Atrium
    3. Ventricle
    4. Outflow tract
  117. 117The outflow tract merges with the ________(1) aorta, which merges with the ________(2) aorta.1. ventral
    2. dorsal
  118. 118_____________(1) blood travels through the _____________(2) and exits through the allantois.1. Deoxygenated
    2. Vitelline arteries
  119. 119During embryogenesis, the foregut and the hindgut move inward, narrowing the connection between the embryo and the yolk sac. 1. What is the name of this connection? 2. What will this eventually form?1. The umbilicus
    2. The umbilical cord
  120. 120What appears in the lateral plate mesoderm by day 3? Be as specific as possible.Limb buds, i.e., the wing bud and the leg bud
  121. 121What happens shortly after the appearance of the limb buds?Shortly after the appearance of limb buds, the extraembryonic folds fuse to enclose the embryo within the embryonic cavity
  122. 1221. What one encompassing process helps elevate the embryo from the disc? Describe the process in some detail. 2. What process does this coincide with? Why is it considered incomplete? 3. What other folding process happens simultaneously? What are the two results of this process?1. Body folding: the head fold, lateral fold, and posterior folds help lift the embryo from the disc.
    2. Body folding coincides with the forming of the gut. It is considered incomplete because it is still connected to the yolk at the umbilicus
    3. Simultaneously, the extraembryonic membranes are forming. The chorion will surround the entire embryo. By doing so, it will also form the amniotic sac.
  123. 123What TWO events occur at day 4?1. The posterior fold forms the hindgut
    2. The opening in the midgut narrows, forming the vitellointestinal duct joining the yolk mass
  124. 124The yolk mass is encased by the ___________(1) which is made up of ____________(2) mesoderm and ___________(3).1. yolk sac
    2. splanchnic
    3. endoderm
  125. 125The amnion is made up of ______________(1) and ___________(2) mesoderm.1. extraembryonic ectoderm
    2. somatic
  126. 126The chorion is made up of ____________(1) and ______________(2) mesoderm.1. ectoderm
    2. somatic
  127. 127TRUE OR FALSE: (Provide a correct statement if false) Splanchnic mesoderm is associated with the body and somatic mesoderm is associated with the gut.FALSE.
    Splanchnic mesoderm is associated with the GUT and somatic mesoderm is associated with the BODY.
  128. 128Where does the extraembryonic endoderm come from, how? What is it known as?The hypoblast is the primitive endoderm. When the definitive endoderm comes in, it displaces the hypoblast out to the sides and it will become the extraembryonic endoderm that is associated with the extraembryonic membranes.
  129. 129The allantois is made up of ___________(1) mesoderm and ___________(2).1. splanchnic
    2. endoderm
  130. 130The gut of the embryo proper is made up of __________(1) and ___________(2) mesoderm.1. endoderm
    2. splanchnic
  131. 131In which direction does organogenesis occur?In the anterior-posterior direction
  132. 1321. What are somites? 2. What are they the precursor to? 3. How are somites formed?1. Somites are segmented mesodermal structures found on either side of the notochord.
    2. They are the precursors to vertebrae
    3. Somites are initially mesenchymal plates that become epithelial through a process called condensation, starting from the anterior and progressing to the posterior
  133. 1331. What are the THREE components of somites? 2. What do they each eventually form? 3. Which of these is closest to the notochord?1. Sclerotome, Myotome, and Dermatome
    2. The sclerotome will form the vertebrae
    The myotome will form segmented muscle and muscle that goes into the limb
    The dermatome forms the dermis
    3.The sclerotome is closest to the notochord
  134. 1341. Which part of the somite hasn't undergone much condensation? 2. Describe the epithelial structures above it and how is named.1. The sclerotome
    2. The inner part of the epithelial structure above it is called the myotome. The outer part is called the dermatome.
  135. 135TRUE OR FALSE: (Provide a correct statement if false) Each somite will form an individual vertebra.FALSE.
    Each somite will NOT form an individual vertebra. Instead, individual vertebrae are composed of the posterior sclerotome of one somite and the anterior sclerotome of the next somite.
  136. 136What is resegmentation?Resegmentation is the phenomenon that encompasses the structure of a vertebra being composed of the posterior sclerotome of one somite and the anterior sclerotome of the next somite.
  137. 137Before the somite breaks into dermatome and myotome, it is known as ____________.dermomyatome
  138. 1381. What does the lateral mesoderm form? 2. What is the precursor to the gonads? 3. Where is the nephric duct located in relation to the precursor to the gonad?1. Kidneys and gonads
    2. Germinal ridge also called the genital ridge
    3. It is found more laterally
  139. 1391. From which germ layer does the posterior part of the wing bud arise? 2. In situ hybridization shows expression of what in this area? 3. What does this molecule mark?1. From the lateral plate mesoderm
    2. Homeobox gene LBX1
    3. It marks the myoblast cells migrating into the limb buds
  140. 1401. What is the myoblast? 2. From which germ layer does it arise? 3. When do we see migration of myoblast cells into the limb buds?1. The myoblast is the precursor to muscle tissue
    2. Intermediate mesoderm
    3. Before the myodermatome has even differentiated into dermatome and myotome
  141. 1411. Where do germ cells come from? 2. Where are germ cells specified?1. Primordial germ cells migrate from the extreme anterior edge of the area pellucida and infiltrate the gonad once it has formed
    2. Germ cells are specified outside the embryo proper    1. Where do germ cells come from? 2. Where are germ cells specified?

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Biology Fichas sobre Chapter 9 Flashcards CHICK, creado por Rosheen Villaraza el 03/11/2018.
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  • Creado por Ana Sarmiento · 2 mar 2016
  • Copiado por Rosheen Villaraza · 3 nov 2018
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