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20 Cards in this Set
- Front
- Back
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When is the embryonic period?
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Week 3-8
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When do major organ systems start to develop?
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All major organ systems start to form during the embryonic period, causing a craniocaudal and lateral body folding of the embryo
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Describe the appearance of the embryo at the end of the embryonic period
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Human-like
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What controls the basic segmentation in the craniocaudal direction of the human body?
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Hox (homeobox) genes
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What is gastrulation?
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A process that establishes the three primary germ layers (ectoderm, mesoderm, and endoderm), thereby forming a trilaminar embryonic disk
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What first indicates the process of gastrulation?
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The formation of the primitive streak within the epiblast
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Throughout gastrulation what happens to the ectoderm?
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It gives further rise to neuroectoderm and neural crest cells
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Throughout gastrulation what happens to the endoderm?
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Remains intact
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Throughout gastrulation what happens to the mesoderm?
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It gives further rise to paraxial mesoderm (somitomeres and 35 pairs of somites), intermediate mesoderm, and lateral mesoderm
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Describe the origin of adult cells and tissues
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All adult cells and tissues can tract their embryological origin back to the three primary germ layers
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Describe a chordoma (CD)
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1. Is either a benign or malignant tumor that arises from remnants of the notochord
2. CD may be found either intracranially or in the sacral region and occurs more commonly in men later in adult life (>50yo) |
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Where are chordomas usually found?
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Intracranially or in the sacral region
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What is usually the first indication of period?
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First missed menstrual period
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When in embryonic develop coincided with the first missed menstrual period?
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Week 3. Not that at this time the embryo has already undergone 2 weeks of development
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Why is it crucial that a woman become aware of a pregnancy as soon as possible?
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The embryoining period is a period of high susceptibility to teratogens
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What is a sacrococcygeal teratoma?
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A tumor that arises from remnants of the primitive streak, which normally degenerates and disappears
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Describe the origin and composition of a sacrococcygeal teratoma
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ST is derived from pluripotent cells of the primitive streak and often contains various types of tissue (eg, bone, nerve, hair)
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In whom do sacrococcygeal teratomas occur?
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ST occurs more commonly in female infants and usually becomes malignant during infancy (must be removed by age 6mo)
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What is caudal dysplasia (sirenomelia)?
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Refers to a constellation of syndromes ranging from minor lesions of lower vertevrae to complete fusion of the lower limbs
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Describe the Defects in Caudal Dysplasia (Sirenomelia)
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VATER: Vertebral defects, anal atresia, tracheoesophageal fistula, and renal defects
VACTERL: Similar to VATER but also includes cardiovascular defects and upper limb defects |
