QUIZ I General Embryology Flashcards Preview

Oral Biology > QUIZ I General Embryology > Flashcards

Flashcards in QUIZ I General Embryology Deck (73)
Loading flashcards...

what is embryology?

the study of prenatal development


what is prenatal development?

begins with the start of pregnancy and continues until birth


what trimesters do the preimplantation, embryonic, and fetal periods make up?

  • preimplantation and embryonic periods - first trimester
  • fetal period - second and third trimesters


each craniofacial structure has what?

a primordium - the earliest indication of a tissue or an organ during prenatal development


what are the steps of development from the zygote to the fetus?

zygote → blastocyst → blastocyst to disc → disc to embryo → fetus


when do the major events of prenatal development occur?

first, second, third, and fourth weeks


describe the general steps of prenatal development

  • fertilization and formation of the zygote
  • mitosis leads to formation of the blastocyst, which forms a fluid filled vesicle and implants in the uterine wall
  • the blastocyst gives way to a disc and begins to differentiate into 3 distinct germ layers
  • these germ layers form the embryo and ultimately, fetus


describe factors driving development

  • growth factors and cell adhesion molecules act through signaling complexes which activate various transcription factors, affecting cellular changes
    • changes might be proliferation, differentiation, or apoptosis


growth factors driving development can act through which modes of action?

autocrine, paracrine, or endocrine


___ is a critical growth factor in craniofacial development

bone morphogenic protein (BMP)


at gastrulation, BMP switches between ___ vs ___ fate

epidermal vs. neural fate


what are the functions of BMP?

  • induction, formation, determination, and migration of neural crest cells
  • patterning and formation of facial primordia
  • craniofacial skeletogenesis (later roles in maintenance)
  • negative regulator of myogenesis (makes bone instead of muscles)
  • regulator of early tooth morphogenesis and differentiation


what are 4 types of genes involved in the control of embryonic formation?

  • HOX genes
  • Msx genes
  • DIx genes
  • Shh (sonic hedgehog) genes


what is the function of HOX genes?

function in patterning the body axis and determine where limbs and other body segments will grown in developing foetus


what is the function of Msx genes?

control cellular process of differentiation and proliferation during development


what is the function of DIx genes?

  • control development of ectodermal tissues derived from lateral border of the neural plate
    • control patterning of the branchial arch skeleton
    • also expressed in developing bone and regulate limb development


what is the function of Shh genes?

play an important role in early induction of facial primordium


what do homeobox genes code for?

  • transcription factors that begin to make cells pattern into one tissue/organ type or another


homeobox genes are involved in ___ ___ during embryonic development

bodily segmentation


homeobox genes are key regulators of what?


help regulate which end is going to be which


what type of DNA sequence is the homeobox gene?

180 bp DNA sequence

homeodomain in protein


___ genes typically switch on cascades of other genes



what type of cell adhesion molecules do neurectoderm and skin ectoderm progenitors express?

  • neurectoderm
    • N-CAM
  • skin ectoderm
    • L-CAM


____ is hugely important for positioning and differentiating

cell-cell contact


cell adhesion molecules are responsible for what?

specific cell aggregation and sorting


which cell adhesion molecules are calcium dependent? calcium independent?

  • calcium dependent
    • cadherins
  • calcium independent
    • CAM


describe the fertilization phase of the preimplantation period

  • first period of prenatal development; occurs during the first week after conception
  • ovum is penetrated by sperm
  • fusion of 2 haploid gametes gives the full diploid complement of 46 (zygote)
  • cell division (mitosis) occurs to form the blastocyst


many human disorders can be traced to changes in what?

structures or number of chromosomes


describe the cleavage phase of the preimplantation period

  • occurs after fertilization when the zygote undergoes mitosis (aka individual cell division or cleavage)
  • morula (solid ball) is formed after initial cleavage 
  • zygote becomes blastocyst
  • further mitotis cleavages, with little to no differentiation involved
  • lasts until 3 distinct germ layers have formed


describe implantation

  • blastocyst stops traveling by the end of the first week
  • it implants in the endometrium 
    • implantation
    • typically on the back wall