DH embryology and histology

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sthomp88
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33904
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DH embryology and histology
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2010-09-11 16:19:45
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embryo
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Quiz 1
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  1. Maxillary and Mandibular Vestibles
    horse-shoe shaped spaces between the lips and the cheeks anteriorly and laterally and the teeth and the gums medially and posterially
  2. Buccal fat pad
    a dense pad of underlying fat tissue at the posterior portion of each vestibule covered by the buccal mucosa
  3. parotid papilla
    small elevation of tissue on the inner portion of the buccal mucosa that protects the opening of the parotid duct
  4. vestibular fornix
    where pink labial or buccal mucose meets the red alveolar mucosa at the mucobuccal fold
  5. retromolar pad
    a dense pad of tissue just distal to the last tooth of the mandibular arch
  6. marginal gingiva
    gingiva at the margin of each tooth, also called free gingiva, which forms a cuff above the neck of the tooth
  7. gingival sulcus
    a space that the inner surface of the gingiva faces
  8. interdental gingiva
    gingiva between adjacent teeth, an extension of attached gingiva
  9. plica fimbriata
    lateral to each deep lingual vein, have fringe like projections
  10. What periods of prenatal development make up the first trimester?
    • Preimplantation period
    • embryonic period
  11. When do most developmental problems in prenatal development occur?
    in the first trimester
  12. teratogens
    environmental agents such as infections, drugs, and radiation that may cause malformations to the fetus
  13. primoridium
    the earliest indication of a part or an organ during prenatal develpment
  14. Preimplantation period
    period of unattached conceptus that takes place during the first week of pregnancy
  15. fertilization
    when a woman's ovum is penetrated by a man's sperm
  16. Zygote
    a fertilized egg formed by the union of the ovum and sperm
  17. When do the final stafes of meiosis occur in the ovum?
    during fertilization
  18. What is the result of the final stages of meiosis during fertilization?
    the ovum's chromosomes join with the sperms chromosomes
  19. When joined together how many chromosomes do the sperm and ovum have?
    diploid number of 46
  20. How is the situation of excess chromosomes in the zygote avoided?
    with meiosis, because during the development of the sperm and ovum, this process emables the ovum and the sperm to reduce by one half the normal number of chromosomes to a haploid number of 23
  21. What process does the zygote undergo after fertilization?
    mitosis
  22. mitosis
    cell division of the zygote
  23. true or false. mitosis of the zygote is an ongoing process
    true
  24. blastocyst
    the collection of cells after the zygotes division
  25. ongoing mitosis causes the blastocyst to what?
    split into smaller and more numerous cells
  26. Approximately how many days into the pregnancy is the zygote called the blastocyst?
    about 5 days
  27. When does mitosis take place versus when meiosis takes place?
    • mitosis-during growth or repair
    • meiosis-during reproduction
  28. As the blastocyst grows, where does it travel, or migrate, to?
    from the site where fertilization took place (fallopian tube) to the uterus
  29. implantation
    blastocyst becomes embedded in the endometruim and continues to divide.
  30. approximately when does implantation occur in the pregnancy
    about 6 days into it
  31. endometrium
    uterin wall
  32. Where is the ideal place for implantation?
    the back wall of the body of the uterus towards the mothers spine
  33. ectopic pregnancy
    dangerous situation where the blastocyst implants somewhere outside of the uterus
  34. after 7 days of cleavage, or mitosis, name the 2 layers that the blastocyst consists of
    • trophoblast layer
    • embryoblast layer
  35. trophoblast layer
    peripheral cell layer, outside cells that will eventually become the prenatal support tissues (placenta, and umbilical circulation)
  36. embryoblast layer
    inner mass of embryonic cells, inner cells that will become the embryo
  37. How does down syndrome occur?
    there is an extra chromosome #21
  38. Embryonic Period
    the second period of prenatal development, extends from the beginning of the second week to the end of the eighth week.
  39. Name the physiological processes that occur during the embryonic period of prenatal development
    • induction
    • proliferation
    • defferentiation
    • morphogenesis
    • maturation
  40. What do the physiological processes in the embryonic stage of development cause the implanted blastocyst to become?
    an embryo
  41. Why are the physiological processes that occur during the embryonic period of prenatal development relevant to dental professionals?
    because theses physiological processes alson allow the teeth and associated structures, as well as other organ structures, to develop in the embryo.
  42. Name and define the first physiological process involved in the beginning of most embryological development.
    • Induction (the pow wow)
    • action of one group of cells on another that leads to the establishment of the developmental pathway in the responding tissue. The cells decide who they are going to be.
  43. True or False. Whatever triggers cells to develop into structures from cellular interactions is poorly understood.
    True
  44. Proliferation
    a type of physiological process that follows induction. it is controlled levels of cellular growth present during most of embryological development.
  45. Cancer
    uncontrolled growth of cells
  46. Name 2 types of proliveration/growth
    • interstitial
    • appositional
  47. Define Interstitial growth, and give examples.
    • growth that occurs from deep within a tissue or organ (like blowing up a balloon)
    • soft tissue growth
  48. Define appositional growth and give an example
    • a tissue enlarges its size by the addition of layers on the outside of a structure (like paint on cinder block)
    • hard tissues such as mature bone or dental tissues
  49. What are examples of some organs that use both interstitial and appositional growth to attain their natural size
    cartilage and growing bone tissue
  50. is growth of an embryo an increase of overall size, like a ballon? If not, then describe.
    No. growth involves differential rates for different tissues and organs. for instance tooth eruption in a child, this occurs over many years allowing for the associated growth of the jaw bones.
  51. differentiation
    physiological process where identically genetic cells start to become structurally and functionally different and start to become tissues.
  52. during what physiological process do major tissues, organs, and organ systems begin to form from specialized cells?
    differentiation
  53. Name the 5 different types/stages of differentiation
    • cytodifferentiation
    • histodifferentiation
    • morphodifferentiation
    • morphogenesis
    • maturation
  54. cytodifferentiation
    development of different cell types
  55. histodifferentiation
    development of different tissues within a structure
  56. morphodifferentiation
    development of the differing structure, or morphology
  57. morphogenesis
    • the complexity of the structure and function of these cells increases
    • the process of development of specific tissue structure or shape
  58. does induction continue to occur during the embryonic period? If so, what is it a result of?
    Yes. it is a result of the new varieties of cells interacting with eachother producing an increasingly complex organism
  59. maturation
    tissues and organs growing up in form, function, and size
  60. If anything goes wrong during the differentiation process, what is usually the end result?
    miscarriage
  61. When is an embryo recognizably human?
    at the end of the embryonic period, or end of the eigth week
  62. What occurs during the second week of prenatal development within the embryonic period?
    the implanted blastocyst grows by increased proliferation of the embryonic cells as well as cellular morphogenesis and differentiation
  63. bilaminar embryonic disc
    forms in the second week. it is the 2 layer meeting point of 2 fluid filled cavities.
  64. name the 2 layers of the bilaminar embryonic disc.
    • epiblast (top layer)
    • hypoblast (bottom layer)
  65. What type of cells is the superior epiblast layer composed of?
    high columnar cells
  66. What type of cells is the inferior hypoblast layer made up of?
    small cuboidal cells
  67. What does the bilaminar disc develop into as prenatal development continues?
    the embryo
  68. Name the 2 fluid-filled sacs that the bilaminar is between when it is suspended in the uterus's endometrium.
    • amniotic cavity
    • yolk sac
  69. amniotic cavity
    faces the epiblast layer
  70. yolk sac
    faces the hypoblast layer, and serves as intial nourishment for the bilaminar embryonic disc
  71. What is the placenta formed from?
    the trophoblast (outside cells) layer, and the endometrium.
  72. The development of what 2 structures permit selective exchange of soluble bloodborne substances between the woman and the embryo?
    the placenta and umbilical circulation system
  73. What is considered the most critical period of prenatal development?
    the embryonic period, because of the beginnings of all essential external and internal structures
  74. Name and describe an example of an infective teratogen that can cross from the placent to the embryo from the pregnant woman that we discussed in class.
    • Syphillis
    • defects in the incisors (hutchinson's incisors) and molars (molberry molars) as well as blindness, deafness, and paralysis
  75. Name and describe an example of a result of a teratogenic drug affect that we discussed in class.
    • fetal alcohol syndrome
    • learning disabilities and deformed facial features
  76. Name and describe an antibiotic therapy of the pregnant woman that can act as a tetarogenic drug during the fetal period that we discussed in class.
    • tetracycline.
    • permanently stains teeth. the antibiotic becomes chemically bonded to the dentin for the life of the tooth.
  77. Primitive streak
    forms in the third week. It is a thickening of cells that splits the epiblast layer of the bilaminar embryonic disc in half. The right and left sides will be symmetrical. by this point, from a top view, the embryo would resemble the sole of a shoe, with a the head end wider than the tail end, and slightly narrowed in the middle.
  78. what does the rod shaped thickening (primitive streak) in the middle of the disc result from?
    increased proliferation of cells in the midline area.
  79. What is mesenchyme? and when does it form?
    • an embryonic connective tissue
    • during the start of the third week
  80. How is mesenchyme formed?
    when some cells from the epiblast (superior) layer move or migrate toward the hypoblast (inferior) layer in the area of the primitive streak and get caught in the middle.
  81. trilaminar embryonic disc
    what the bilaminar embryonic disc turns into after the mesenchyme is formed. It now consists of 3 layers instead of 2.
  82. What are the 3 layers of the trilaminar embryonic disc now called?
    • ectoderm (was previously the epiblast layer)
    • mesoderm (from mesenchyme)
    • endoderm (was previoulsy the hypoblast layer)
  83. What does the ectoderm layer give rise to?
    • structures on the outside of the body:
    • epidermis
    • sensory epithelium of the eyes, ears, and nose (senses)
    • nervous system
    • neural crest cells
  84. What does the mesoderm give rise to?
    • structures more in the middle of the body such as:
    • dermis
    • connective tissue
    • muscle
    • bone
    • lymphatics
    • blood cells
    • bone marrow
    • carilage
    • reproductive organs
    • excretory organs
  85. What does the endoderm layer give rist to?
    • structures on the very very inside of the body such as:
    • respiratory system linings
    • digestive system linings
    • liver cells
    • pancreatic cells
  86. What is ectodermal displasia?
    abnormal development of the ectoderm. Affects the teeth, skin, hair, nails, facial structures, and glands. You will survive this situation, usually no miscarriage, and it is usually genetic.
  87. cephalic end
    head end of the embryo (wide end of the shoe)
  88. what structure is formed at the cephalic end of the embryo? and what will it eventually become?
    • oropharyngeal membrane consisting of ONLY the ectoderm layer externally, and endoderm layer internally.
    • it will eventually become the primitive mouth and beninning of the digestive tract
  89. caudal end
    tail end (more narrow part of the shoe)
  90. what structure is formed at the caudal end of the embryo? And what will it eventually become?
    • The cloacal membrane (consists of only the ectoderm layer and endoderm layer)
    • it will eventually become the anus and terminal end of the digestive tract
  91. At what point does the central nervous system begin to develop in the embryo?
    during the later part of the third week of prenatal development
  92. neuroectoderm
    specialized group of cells the differentiate from the ectoderm and are localized to the neural plate of the embryo.
  93. neural plate
    where all the neuroectoderm hangs out. A band of cells that extends the length of the embryo from the cephalic end to the caudal end
  94. neural groove
    the plate starts to thicken and deepen further which forms this groove
  95. neural fold
    the plate sinks even deeper and forms this fold
  96. neural tube
    the neural folds meet superior to the neural groove and form this tube which fuses at the top and becomes the spinal cord
  97. name and describe a type of neural tube defect that we discussed in class.
    • spina bifida
    • results as failure of fusion of the neural tube. it is characterized by defects in the verebral arches and various degrees of disability.
  98. What are some prenatal vitamins that can be given to help preven spina bifida, cleft lip, and cleft palate?
    folic acid (vitamin B9)
  99. what are nueral crest cells? And what do they give rise to?
    • specialized cells the develop from the neuroectoderm and give rise to:
    • connective tissue
    • cartilage
    • bone
    • dental tissues
  100. what do many embryologists consider the neural crest cell to be?
    a fourth embryonic layer
  101. once the neural crest cells reach their predetermined destinations, what happens with them?
    the unergo differentiation into diverse cell types that are in part specified by local environmental influences
  102. What are somites? And what do they eventually give rise to?
    • 38 paired blocks of mesoderm along both sides of the neural tube
    • give rise to:
    • skin
    • bones of head and neck
  103. where do neural crest cells migrate from? and where do they disperse to?
    migrate from the crest cells of the neuro folds, and disperse within the mesenchyme
  104. What is the main process that occurs during the 4th week of the embryonic period? Describe this process
    • embryonic folding
    • the disc starts to fold-establishing the human axis and placing the tissues in their proper formation for further development by extensive proliferation of the ectoderm, and differentiation of basic tissues.
  105. After embryonic folding, describe where the layers are in relation.
    endoderm is on the inside of the ectoderm, with the mesoderm filling in areas between these two layersl. this forms one hollow tube lined by the endoderm from the cephalic end to the caudal end of the embryo- or from the oropharynegeal membrane to the cloacal membrane.
  106. What does that tube formedby embryonic folding become in the future?
    the digestive tract
  107. name the 3 major regions of the tube formed by embryonic tubing.
    • foregut
    • midgut
    • hindgut
  108. foregut
    anterior section of the tube which eventually forms the throat. It also inclueds a protion of the primitive yolk sac as it becomes enclosed with folding.
  109. midgut
    middle section of the tube-forms the rest of the pharynx, and the rest of the digestive tract
  110. hindgut
    posterior section of the tube- forms the rest of the digestive tract
  111. What other structures begin to develop during the fourth week of prenatal development?
    face, neck, and oral structures
  112. Fetal period
    beginning of 9th week, or third to ninth month. It is a time of maturation. Allows the newly formed tissues and organs to function
  113. When does the embryo become a fetus?
    during the fetal period of prenatal development
  114. When can you detect the heartbeat of the fetus? And when can the mother recognize fetal movements?
    by the fourth month

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