Flashcards in Important genes of embryogenesis/Early Fetal Devo EC Deck (26):
Produced at the base of limbs in zone of polarizing activity. Involved in patterning along anterior-posterior axis. Involved in CNS development; mutation can cause holoprosencephaly.
Sonic hedgehog gene
Produced at apical ectodermal ridge (thickened ectoderm at distal end of each developing limb). Necessary for proper organization along dorsal-ventral axis.
Produced at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs.
Involved in segmental organization of embry in craniocaudal direction. Mutations cause appendages in wrong locations.
Homeobox (Hox) genes
Week 1 of embryogenesis
Zygote (day 2), Morula (day 3), Blastocyst (day 5), Implantation (day 6)
hCG secretion begins after implantation (+ pregnancy test)
Week 2 of embryogenesis
Bilaminar disc (Epiblast [will become 3 layers] and Hypoblast [becomes yolk sac])
"2 weeks=2 layers"
Week 3 of embryogenesis
Primitive streak, Notochord, Mesoderm organization, Neural plate begin to form
"3 weeks=3 layers"
Embryonic period (weeks 3-8)
Neural tube formed by neuroectoderm and closes by week 4
Extremely susceptible to teratogens
Week 4 of embryogenesis
Heart begins to beat
Limb buds begin to form
"4 weeks=4 limbs"
Week 8 of embryogenesis
Start of fetal period
Fetal movement/looks like a baby
Week 10 of embryogenesis
Genitalia have male/female characteristics
Process that forms trilaminar embryonic disc. Establishes the ectoderm, mesoderm, and endoderm germ layers. Starts with the epiblast invaginating to form the primitive streak.
What are the three divisions of the ectoderm?
Adenohypophysis (from Rathke's pouch), lens, epithelial lining of oral cavity, sensory organs of ear, olfactory epithelium. Epidermis, anal canal below pectinate line, parotid, sweat, and mammary glands.
Benign Rathke's pouch tumor with cholesterol crystals and calcifications
Brain, retina/optic nerve, and spinal cord
PNS, Melanocytes, Chromaffin cells of adrenal medulla, Parafollicular cells of thyroid, Pia and Arachnoid, Bones of skull, odontoblasts, aorticopulmonary septum.
Muscle, bone, CT, Serous lining of body cavities, spleen, CV structures, Lymphatics, Blood, Wall of gut tube, Wall of bladder, Urethra, Vagina, Kidneys, Adrenal cortex, Dermis, Gonads
Limb defects (bone and muscle)
Induces ectoderm to form neuroectoderm (neural plate). It's only postnatal derivative is the nucleus pulposus.
Gut tube epithelium (including anal canal above pectinate line), lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, thyroid follicular cells)
Absent organ due to absent primordial tissue
Absent organ despite primordial tissue
Extrinsic disruption; occurs after the embryonic period
Incomplete organ development; primordial tissue present.