Embryology Flashcards
Gene that organizes anteroposterior axis
Sonic hedgehog gene
Mutation in this gene can cause holoprosencephaly
Sonic hedgehog gene
Where is sonic hedgehog gene produced?
Base of limbs
Gene that organizes dorsal-ventral axis
WNT-7 gene
Thickened ectoderm at distal end of each developing limb
Dermal ectodermal ridge
Gene that causes mitosis of mesoderm and lengthens limbs
FGF gene
Where is the FGF gene produced?
Apical ectodermal ridge
Where is the WNT-7 gene produced?
Apical ectodermal ridge
Mutation in this gene causes limbs to be in wrong places
HOX gene
Gene that organizes segmental organization in a craniocaudal direction
HOX gene
During which week of development does hCG secretion begin?
week 1
During which week of development does the blastocyst implant?
week 1
During which week of development does the bilaminar disk form?
week 2
What tissues make up the bilaminar disk?
epiblast and hypoblast
Where does the notochord arise from?
Midline mesoderm
What becomes the neural plate?
ectoderm
The epiblast invaginates to form what?
Primitive streak
During which week of development do endoderm, ectoderm, and mesoderm form?
Week 3
During which week of development does neural tube form?
Week 3
By which week of development does the neural tube close?
week 4
During which weeks does organogenesis occur?
Weeks 3-8
The embryonic period occurs within which weeks?
Weeks 3-8
Which period of embryo development is most susceptible to teratogens?
Embryonic period (weeks 3-8)
During which week of development does the heart begin to beat?
week 4
During which week of development do limbs begin to appear
week 4
During which week of development is fetal cardiac activity visible by transvaginal ultrasound?
week 6
During which week of development do fetal movements start?
week 8
During which week of development do genitalia develop male and female characteristics?
week 10
Benign Rathke pouch tumor with cholesterol crystals and calcifications
Craniopharyngioma
Adenohypophysis is derived from what tissue?
Rathke pouch (surface ectoderm)
Embryonic tissue that gives rise to lens of the eye
surface ectoderm
Embryonic tissue that gives rise to epithelial linings of oral cavity
surface ectoderm
Embryonic tissue that gives rise to sensory organs of ear and olfactory epithelium
surface ectoderm
Embryonic tissue that gives rise to anal canal below the pectinate line
surface ectoderm
Embryonic tissue that gives rise to parotid, sweat and mammary glands
surface ectoderm
Embryonic tissue that gives rise to CNS structures and cells
Neural tube (Neuroectoderm)
Embryonic tissue that gives rise to PNS structures and cells
Neural crest (ectoderm)
Embryonic tissue that gives rise to melanocytes
Neural crest (ectoderm)
Embryonic tissue that gives rise to chromaffin cells of adrenal medulla
neural crest (ectoderm)
Embryonic tissue that gives rise to parafollicular (C) cells of thyroid
neural crest (ectoderm)
Embryonic tissue that gives rise to pia and arachnoid
neural crest (ectoderm)
Embryonic tissue that gives rise to bones of the skull
neural crest (ectoderm)
Embryonic tissue that gives rise to aorticopulmonary septum
neural crest (ectoderm)
Embryonic tissue that gives rise to endocardial cushions
neural crest (ectoderm)
Embryonic tissue that gives rise to myenteric (Auerbach) plexus
neural crest (ectoderm)
Embryonic tissue that gives rise to muscle, bone and connective tissue
mesoderm
Embryonic tissue that gives rise to serous linings of body cavities
mesoderm
Embryonic tissue that gives rise to the spleen
mesoderm
Embryonic tissue that gives rise to cardiovascular structures
mesoderm
Embryonic tissue that gives rise to lymphatics and blood
mesoderm
Embryonic tissue that gives rise to wall of gut tube
mesoderm
Embryonic tissue that gives rise to upper vagina, testes and ovaries
mesoderm
Embryonic tissue that gives rise to kidneys and adrenal cortex
mesoderm
What induces ectoderm to form neuroectoderm
Notochord
What is the postnatal derivative of the notochord
The nucleus pulposus of the intervertebral disk
Embryonic tissue that gives rise to gut tube epithelium including anal canal above the pectinate line
endoderm
Embryonic tissue that gives rise to most of urethra and lower vagina
endoderm
The urogenital sinus gives rise to what part of the vagina?
lower vagina
Embryonic tissue that gives rise to lungs, liver, gallbladder, pancreas
endoderm
Embryonic tissue that gives rise to thymus, parathyroid, and thyroid follicular cells
endoderm
Embryonic tissue that gives rise to the Eustachian tube
endoderm
Absent organ due to absent primordial tissue
agenesis
Absent organ despite presence of primordial tissue
aplasia
Incomplete organ development; primordial tissue present
hypoplasia
2ndry breakdown of previously normal tissue or structure
disruption
extrinsic disruption after embryonic period
deformation
intrinsic reaction during embryonic period
malformation
abnormalities resulting from a single primary embryological event (oligohydramnios)
Sequence (Potter sequence from oligohydramnios)
Teratogen that causes renal damage
ACE inhibitors
Teratogen that causes absence of digits and multiple anomalies
Alkylating agents
Teratogen that causes ototoxicity
Aminoglycosides
Teratogen that causes neural tube defects, cardiac defects, cleft palate and skeletal abnormalities
Antiepileptic drugs
Most common antiepileptic drugs that cause neural tube and cardiac defects, cleft palate and skeletal abnormalities
Valproate, carbamazepine, phenytoin, phenobarbital
Teratogen that causes vaginal clear cell adenocarcinoma and congenital Mullerian anomalies
Diethylstilbestrol
Folate antagonists that cause neural tube defects
Trimethoprim, methotrexate, antiepileptic drugs
Teratogen that causes multiple birth defects and requires mandatory contraception
Isotretinoin
Teratogen that causes Ebstein anomaly
Lithium
Teratogen that causes aplasia cutis congenita
Methimazole
Teratogen that causes discolored teeth and inhibited bone growth
Tetracycline
Teratogen that causes limb defects
Thalidomide
Teratogen that causes bone deformities, fetal hemorrhage, abortion, and eye abnormalities
Warfarin
Teratogen that causes intellectual disability and other birth defects
Alcohol
Teratogen that causes low birth weight, preterm birth, IUGR, placental abruption
cocaine
Teratogen that causes low birth weight, preterm labor, placental problems, IUGR, SIDS in developing countries
Smoking, nicotine or CO
What is the effect of cocaine on blood vessels
Vasoconstriction
What is the effect of nicotine on blood vessels
Vasoconstriction
Lack of this nutrient will lead to congenital goiter or hypothyroidism (cretinism)
Iodine
Condition in mother that can cause caudal regression syndrome, congenital heart defects, neural tube defects, micromsa, and neonatal hypoglycemia
Maternal diabetes
Can cause neurotoxicity and found in highest concentrations in swordfish, shark, tilefish, and king mackerel
Mercury
High amounts of this vitamin increases risk of spontaneous abortion and birth defects
vitamin A
Anal atresia and sirenomalia can be caused by what maternal condition?
Maternal diabetes
Needs to be minimized by lead shielding to avoid microcephaly and intellectual ability in developing fetus
X-rays
What is the leading cause of intellectual disability in the U.S?
Fetal alcohol syndrome
Child presenting with intellectual disability and has smooth philtrum, thin vermillion border and small palpebral fissures is also at risk for what other complications?
Heart and limb defects and holoprosencephaly
Holoprosencephaly is caused by what?
Trisomy 13 or alcohol
What type of twins are fraternal twins?
Dizygotic
What number of chorions and amnions will be present if twinning occurs during 0-4 days?
dichorionic and diamniotic
What number of chorions and amnions will be present if twinning occurs during 4-8 days?
monochorionic and diamniotic
What number of chorions and amnions will be present if twinning occurs during 8-12 days?
one chorion and amnion
What number of chorions and amnions will be present if twinning occurs > 13 days?
one chorion and amnion - maybe conjoined
What is the cell stage if twinning occurs in 0-4 days?
2 cell stage
What is the cell stage if twinning occurs in 4-8 days?
Morula
What is the cell stage if twinning occurs in 8-12 days?
Blastocyst
What is the cell stage if twinning occurs in > 13 days?
Formed embryonic disc
Which layer of the chorionic villi makes ?
cytotrophoblast
which layer of the chorionic villi synthesizes hormones
syncytiotrophoblast
Which layer of the chorionic villi is the inner layer ?
cytotrophoblast
Which layer of the chorionic villi is the outer layer
syncytiotrophoblast
Hormone that is structurally similar to LH and stimulates corpus luteum to secrete progesterone during first trimester
hCG
Vessels that return deoxygenated blood from fetus to placenta
Umbilical arteries
Supplies oxygenated blood from placenta to fetus
Umbilical vein
The umbilical arteries return blood from fetus via what main arteries?
Internal iliac arteries
What blood vessel does the umbilical vein drain into?
IVC via ductus venosus
What structures are found in the umbilical cord?
2 umbilical arteries
1 umbilical vein
Allantoic duct
Wharton jelly
During which week of development is the allantois formed?
week 3
To where does the allantois extend?
urogenital sinus
What does the allantois become?
Urachus
Where is the urachus located?
between the fetal bladder and umbilicus
What causes urine to discharge from the umbilicus
Patent urachus - failed to obliterate
What is a fluid-filled cavity lined with epithelium between the umbilicus and bladder?
Urachal cyst
What is the cause of a urachal cyst?
Partial failure of urachus to obliterate
What is a complication of an urachal cyst?
Infection or adenocarcinoma
What is an outpouching of the bladder called?
Vesicourachal diverticulum
What causes a Vesicourachal diverticulum?
Slight failure of urachus to obliterate
During which week of development does the vitelline duct obliterate?
week 7
What does the vitelline duct do?
Connects yolk sac to midgut lumen
What usually causes meconium discharge from umbilicus?
Vitelline fistula - fails to close
Usually presents with melena, hematochezia, and abdominal pain and is attached to ileum
Meckel diverticulum (a true diverticulum)
What causes Meckel diverticulum?
Partial closure of vitelline duct
Aortic arch that gives rise to part of maxillary artery
1st
Aortic arch that gives rise to stapedial and hyoid arteries
2nd
Aortic arch that gives rise to common carotid and proximal part of the internal carotid artery
3rd
Aortic arch that gives rise to aortic arch and proximal part of right subclavian artery
4th
Aortic arch that gives rise to proximal part of pulmonary artery on the left and ductus arteriosus
6th
The right recurrent laryngeal nerve loops around which vessel?
Right subclavian artery
The left recurrent laryngeal nerve loops around which vessel?
Aortic arch distal to ductus arteriosus
Branchial clefts are derived from which embryological tissue?
ectoderm
Branchial arches are derived from which embryological tissue?
mesoderm
Branchial pouches are derived from which embryological tissue?
endoderm
Mnemonic to remember branchial apparatus
CAP covers outside to inside:
C = ectoderm (C=clefts)
A = mesoderm (A=arches)
P = endoderm (P=pouches)
What does the first branchial cleft develop into?
external Auditory meatus (A is 1st letter of alphabet)
Cyst within lateral neck located anterior to SCM muscle and is immobile during swallowing?
Persistent cervical sinus
What causes a persistent cervical sinus?
Failure of 2nd - 4th branchial clefts to obliterate
branchial arch that gives rise to CN V2 and V3
1st
branchial arch that gives rise to maxillary process, mandibular process, malleus and incus, and sphenomandibular ligament
1st
Maxilla and zygoMatic bone are derived from which brachial arch?
1st
Meckel cartilage and Mandible are derived from which brachial arch?
1st
Malleus and incus are derived from which brachial arch?
1st
sphenoMandibular ligament is derived from which brachial arch?
1st
Muscles of Mastication are derived from which brachial arch?
1st
temporalis Masseter, lateral and Medial pterygoids are derived from which brachial arch?
1st
Mylohyoid, anterior belly of digastric, tensor tympani, and anterior 2/3 of tongue are derived from which brachial arch?
1st
Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament are derived from which brachial arch?
2nd
Muscles of facial expression are derived from which brachial arch?
2nd
CN VII is derived from which brachial arch?
2nd
Stapedius, Stylohyoid, platySma, and posterior belly of the digastric are derived from which brachial arch?
2nd
Someone with a small jaw, displaced tongue, cleft palate, and airway obstruction has what sequence?
Pierre Robin sequence
Someone with a small jaw, displaced tongue, cleft palate, and airway obstruction has a defect in which brachial arch?
1st
Pierre Robin sequence and Treacher Collins syndrome can be caused by defects in which brachial arch?
1st
Someone with neural crest dysfunction causing mandibular hypoplasia and facial abnormalities has what syndrome?
Treacher Collins syndrome
Someone with neural crest dysfunction causing mandibular hypoplasia and facial abnormalities has a defect in which brachial arch?
1st/2nd
Branchial arch that gives rise to Greater horn of hyoid
3rd
Branchial arch that gives rise to CN IX (glossopharyngeal nerve)
3rd (3x3=9)
Branchial arch that gives rise to stylopharyngeus
3rd
Nerve that innervates stylopharyngeus
CN IX (glossopharyngeal nerve)
Branchial arch that gives rise to Arytenoids, Cricoid, Corniculate, Cuneiform, Thyroid cartilage (ACCCT)
4th and 6th
Branchial arch that gives rise to most pharyngeal constrictors, cricothyroid and levator veli palatini
4th
Branchial arch that gives rise to all intrinsic muscles of larynx except cricothyroid
6th
Branchial arch that gives rise to superior laryngeal branch of CN X
4th
Branchial arch that gives rise to recurrent laryngeal branch of CN X
6th
Function of superior laryngeal branch of CN X
Swallow
Function of recurrent laryngeal branch of CN X
Speaking
What branchial arches contribute to the posterior 1/3 of the tongue?
3rd and 4th
