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113 Cards in this Set
- Front
- Back
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Period during which the risk for birth defects is the highest
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During the embryonic period
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What forms the neural tube?
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the lateral neural forms
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The neural folds are temporarily incomplete where
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At the cranial and caudal neurotropes (close at day 25 and day 27)
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What cells separated from the junctin of the neural tube and neural fold
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Neural crest cells
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When do the first somites appear
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Day 20
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The liver becomes the major hematopoietic orgaan of the fetus when?
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By week 6
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When does bone marrow become the definitive blood-forming organ?
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After the seventh month of gestation
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What is the pre-embryonic period?
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Weeks 1-2
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Whatis the emryonic period?
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Weeks 3-8 where oganogenesis occurs
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What is the fetal period?
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After emybryonic till birth
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What cells under go meiosis?
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Germ cells
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What are the nonfunctinal oocytes called and how many functional and non-functional oocytes are there?
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Polar bodies and only 1 functional and three not
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What is nondisjunction?
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Abnormal meiosis having a numerical chromosomal abnormality
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Where does fertilization occur usually?
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Ampulla
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The dividing cells during cleavage are called what?
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blastomeres
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What is the thingy called at the 16-cell stage?
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Morula
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what is the inner cell mass of the morula called? And the outer?
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embryoblast is the inner and tophoblast is the outer cell mass
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What will the tropoblast contribute to?
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The placenta
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What is the fluid filled cavity that penetrates between blastomeres?
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Blastocyst cavity or blastocele
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When does the zygote implant on the uterus?
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5.5-6 days after feritlization
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Where do the majority of monozygotic twins split?
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At the early blastocyst stage
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What are the risk outcomes with pregnancies involving twins?
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Death of twins, low birth weight and premature birth
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What is the term for conjoined twins in the sacral region?
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Pygopagus
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What is monosomy
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one too few chromosomes
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Where do 95% of ectopics occur and where else can they?
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Uterine tube is the most common; rectouterine pouch, ovary or elsewhere
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What is placenta previa?
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Implantation of the zygote close to the internal os leading to bridging the opening of the uterus, which results in hemorrhaging late in pregnancy
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What is the bilaminar germ disc?
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When the cells of the embryoblast differentiate into two layers. This happens during the second week
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What are the two layers of the germ disc?
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Epiblast and hypoblast
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Where does the amniotic cavity form?
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within the epiblast
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what are amnioblasts?
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part of epiblast adjacent to the cytotrophoblasts
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What is gastrulation?
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when the three germ layers form (ecto, endo and mesoderm)
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How is mesoderm formed?
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Cells from the epiblast migrate into the primitive streak and pit (detach from epiblast or invaginate from the epiblast) and form the mesoderm and part of the endoderm with the hypoblast
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How is the notocord formed?
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Invaginating cells (just like mesoderm) migrate cephalically in the midline and form it and also prechordal mesoderm
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Where does prechordal mesoderm lie?
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Between the tip of the notochord and the buccopharyngeal/oropharyngeal membrane
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Head development results from molecular signals from what?
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Anterior visceral endoderm, which establishes the cranial end
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The primitive streak froms under control of genes in ?
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The primitive node
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Holoprosencephaly? And may be caused by?
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cyclops, alcohol
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What is the abnormality with insufficient mesoderm in the caudal part
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Sirenomelia (caudal dysgenesis)
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What is the abnormality when tumors form from remnants of the primitive streak?
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sacrococcygeal teratoma (most common tumor in newborns)
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What is situs inversus?
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Transposition of organs…oops heart is on the right…woa
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What is twin transfusion syndrome?
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When blood supply to one was less and usually results in death of one
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What is teratology?
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study of causes mechanisms and manifestatinos of developmental defects
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50% of all pregnancies end in spontaneous abortion?
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Yep
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2-3% of live newborns have major malformations
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Yep
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20% of deaths during the first postnatal year due to?
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developmental defects
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What percent of developmental defects include chromosomal abnormalities?
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6-7%
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How about unknow causes of development defects?
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50-60%
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Multifactorial etiology of developmental defects percent?
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20-25%
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What can cause anomalies in development?
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Genetic factors, environmental factors (drugs, chemicals, infections), and multifactorial (genetic and environmental)
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What is aneuploidy?
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Multiple of one or more chromosomes (monosomy, trisomy, tetrasomy, etc.)
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Polyploidy?
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an exact multiple of the haploid number, so 69, 92…. Woa
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Absense of ovaries is called what and happens in what disease?
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Monosomy of sex chromosome: Turner syndrome
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Three most common tirsomy?
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21, 18, 13
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Down syndrome is trisomy of?
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chromosome 21
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Atlantoaxial instability is what and occurs in what syndrome and what percent in that syndrome?
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Instability of neck and occurs in down syndrome (15% in down)
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What percent of Turner are thought to be spontaneously aborted?
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99%
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What is the incidence of Down syndrome at age 45?
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1 in 25 due to meiotic nondisjunction as maternal age increases
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Klinefelter syndrome is?
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Trisomy of Sex XXY, tall, gynecomastia, incidence (1 in 500), broad)
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What percent of Klinefelter have gynecomastia and are at risk for?
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40% and risk of developing breast cancer
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Common type of polyploidy?
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Triploidy (3, 4, ….x whole number of chromosomes = 69, 92, etc) woa
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Structural abnormalities of chromosomes include?
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Deletion, translocation, duplication, inversion, isochromosome
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Example of deletion (loos of part of the chormosome)?
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cri du chat syndrome (partial deletion of chromosome 5)
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What are Isochromosomes and is involved in what syndrome
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Transverse division of the centromere, rather than two arms of each chromotid; Turner
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What is Mosaicism?
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Mitotic nondisjunction of chromosomes
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Environmental agents that can cause developmental defects?
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Drugs, radiation, chemicals, mechanical forces and infectious agents
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Drugs?
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Thalidomide, alcohol, aminopterin, retinoic acide (Vitamin A), phenytoin
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Thalidomide?
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Caused developmental abnormalities in 10k+ in West Germany and Australia: caused limb defects (amelia or meromelia or phocomelia)
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Alcohol causes what?
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Fetal alcohol syndrome (microcephaly, maxillary hypoplasia, palpebral fissures, joint abnormalities, and cardiovascular
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Aminopterin?
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A folic acid antagonist used to treat leukimia, causes skeletal and CNS defects, clubfeet anencephaly, etc.
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Isotretinoin?
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(analogue of vitamin A used for acne treatment oral) Can cause any type of defect, such as neural tube defect.
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What causes fetal hydantoin?
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caused by phenytoin, an anticonvulsant
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What causes fetal minamata disease (mental retardation and blindness)?
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Methylmercury
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What is especially sensitive to ionizing radiation?
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The CNS: microcephaly, spina bifida, cleft palet
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Too little amniotic fluid can cause what?
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Oligohydramnios
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Fetal head restraint usually occurs from what type of pregnancies?
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Twin or tiplet
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What virus can cause cataracts and glycoma?
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Reubella virus
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What can cause microphthalmia?
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Cytomegalovirus
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Most major malformatios occur in exposure during what period of development?
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embryonic
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What can cause hydrocephalus?
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Toxoplasma gondii
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Where does the chorionic cavity come from?
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extraembryonic mesoderm
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Ectoderm germ layer gives rise to what?
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CNS, PNS, sensory epithelium of the eye, nose, ear and epidermis of the skin, hair, nails and subcutaneous glands, pituitary gland and tooth enamel
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Where dpes the conotruncal septum of the hear come from?
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Neural crest cells
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What else do the neural crest cells make?
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Spinal and sensory ganlia of cranial nerves V, VII, IX, X, autonomic ganglia, adrenal medula, schwann cells, connective tissues of the anterior part of the skull and meninges, melanocytes, c cells of the thyroid gland
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What are the three parts of mesoderm?
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Paraxial, intermediate and lateral plate
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What does the sclerotome form?
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cartilage and bone of the axial skeleton, including vertebral column
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What does the dorasl dermatome form?
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Forms the dermis of the skin
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What does the intermediate mesoderm form?
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Urogenital structures
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Lateral plate mesoderm diveds into what two layers?
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somatic/parietal and the splanchnic visceral layer
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The two layers formed by the mesoderm are separated by what?
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intraembryonic cavity
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Where does blood vessel formation occur?
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in mesoderm near yolk sac at 3 weeks then from lateral plate mesoderm
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What organ becomes the majore hamatopoietic organ of the fetus by week 6?
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Liver
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What are the three parts of the gastrointestinal tract?
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Cephalic foregut (buccopharyngeal to liver, the hindut (tail) and midgut (connected to yolk sac by the viteline duct)
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Where does the respiratory system come from?
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Lung bud….an outgrowth, respiratory diverticulum from the ventral wall of the foregut
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What else does the endodermal germ layer contribute to?
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Urinary bladder, urethra, thyroid and parathyroid glands, liver and pancreas, tonsils, thymus,llining of typanic cavity and auditory tube
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When does the formation of the placenta begin?
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At the morula stage
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The morula and blastocyst consist of what two layers of cells?
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An inner cell mass (embryoblasts) and outer (trophoblast)
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In the second week of development what are the two layers of the trophoblast?
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outer syncytiotrophoblast, and inner cytotrophoblast
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What do the synctiotrophoblasts do?
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erode the endometrium
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What is the decidua reaction?
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Endometrial cells around the conceptus become loaded with glycogen and lipids
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How is the uteroplacental circulation established?
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Lacunae in the synctiotrophoblast invade capillaries and make sinusoids and the flow of maternal blood forms
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Excess Amnionic fluid is called?
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polyhydramnios
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Deficient amnionic fluid?
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oligohydramnios
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What contributes to the umbilical cord coming out of the umbilical ring?
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Connecting stalk and the vitelline duct
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What are the two types of bone formation?
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Intramembranous abd endochondral
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Where do the intervevertebral discs form in the sclerotome?
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Between the the cephalic and caudal halves
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Whay bridge intervertebral discs?
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Myotomes develop muslces there that can move adjacent vertebrae
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What is spina bifida occulta?
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Spina bifida covered by pigmented skin or hair
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during the 7th week, the upper limbs rotate 90 degrees in what direction and how bout the lower?
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Upper laterally and lower medially where ever thumb and big toe are
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What is the roof of the skull called and the base?
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calvaria and base is chondrocranium
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What is the soft spot on a baby's head?
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Anterior frontanelle
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When suture fuse permanently?
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craniosynostosis, growth restricted at sutures and overgrowth to compensate in non closed ones
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What is the most common craniosynostosis?
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scaphocephaly
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What is prune belly syndrome?
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Missing abdominal muscles and associated with pulmonary hypoplasia due to lung compression in oligohydramnios as is associated with urinary tract obstruction
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