Embryology [Repro] Flashcards
Where is the sonic hedgehog gene expressed?
Base of limbs in zone of polarizing activity
Where is the Wnt-7 gene expressed?
Apical ectodermal ridge (distal end of limb bud)
Where is the FGF gene expressed?
Apical ectodermal ridge (distal end of limb bud)
Sonic hedgehog gene is involved with patterning of which body axis?
Anterior-posterior
Wnt-7 gene is involved with patterning of which body axis?
Dorsal-ventral
What processes are directed by Hox genes?
Segmentation of embryo in cranial-caudal axis
What kinds of defects are caused by Hox mutations?
Appendages in wrong places
What is the effect of the FGF gene?
Stimulates mitosis of underlying mesoderm, lengthening of limbs
What defines “Day 0” of embryogenesis?
Fertilization of egg by sperm
The embryo implants and begins secreting hCG during […] of embryogenesis.
The embryo implants and begins secreting hCG during week 1 of embryogenesis.
The embryo develops into a bilaminar disk by […] of embryogenesis.
The embryo develops into a bilaminar disk by week two of embryogenesis.
[2 weeks = 2 layers]
The embryo develops into three layer during […] of embryogenesis.
The embryo develops into three layer during week three of embryogenesis.
[3 weeks = 3 layers]
The primitive streak, notochord, mesoderm, and neural plate form during week […] of embryogenesis.
The primitive streak, notochord, mesoderm, and neural plate form during week 3 of embryogenesis.
Organogenesis occurs during weeks […] of embryogenesis.
Organogenesis occurs during weeks 3-8 of embryogenesis.
Growing embryos are most susceptible to teratogens during […] of embryogenesis.
Growing embryos are most susceptible to teratogens during weeks 3-8 i.e. the embryonic period of embryogenesis.
The heart begins to beat during […] of embryogenesis.
The heart begins to beat during week 4 of embryogenesis.
The limb buds begin to form during […] of embryogenesis.
The limb buds begin to form during week 4 of embryogenesis.
[4 weeks = 4 limbs]
The fetal period begins at […] of embryogenesis.
The fetal period begins at week 8 of embryogenesis.
Fetal movement is first observed during week […] of embryogenesis.
Fetal movement is first observed during week 8 of embryogenesis.
Genitalia become visibly different by […] of embryogenesis.
Genitalia become visibly different by week 10 of embryogenesis.
The three germ layers are […].
The three germ layers are endoderm, mesoderm, and ectoderm.
What process establishes the embryonal germ layers?
Gastrulation
Implantation usually occurs near […] of embryogenesis.
Implantation usually occurs near day 6 of embryogenesis.
The three divisions of the ectoderm are […].
The three divisions of the ectoderm are surface ectoderm, neuroectoderm, and neural crest.
The adenohypophysis derives from what germ layer?
Surface ectoderm
The Rathke’s pouch derives from what germ layer?
Surface ectoderm
The lens of the eye derives from what germ layer?
Surface ectoderm
The epithelial linings of oral cavity derives from what germ layer?
Surface ectoderm
The sensory organs of the ear derives from what germ layer?
Surface ectoderm
The olfactory epithelium derives from what germ layer?
Surface ectoderm
The epidermis derives from what germ layer?
Surface ectoderm
The anal canal BELOW the pectinate line derives from what germ layer?
Surface ectoderm
The parotid, sweat, and mammary glands derives from what germ layer?
Surface ectoderm
The neurohypophysis derives from what germ layer?
Neuroectoderm
The pineal gland derives from what germ layer?
Neuroectoderm
The retina derives from what germ layer?
Neuroectoderm
The optic nerve derives from what germ layer?
Neuroectoderm
The spinal cord derives from what germ layer?
Neuroectoderm
The dorsal root ganglia derives from what germ layer?
Neural crest
The cranial nerves derives from what germ layer?
Neural crest
The celiac ganglion derives from what germ layer?
Neural crest
The autonomic nervous system derives from what germ layer?
Neural crest
The melanocytes derives from what germ layer?
Neural crest
The chromaffin cells of adrenal medulla derives from what germ layer?
Neural crest
The parafollicular cells (C-cells) of thyroid derives from what germ layer?
Neural crest
The pia mater derives from what germ layer?
Neural crest
The arachnoid mater derives from what germ layer?
Neural crest
The bones of the skull derives from what germ layer?
Neural crest
The odontoblasts derives from what germ layer?
Neural crest
The aorticopulmonary septum derives from what germ layer?
Neural crest
The muscle derives from what germ layer?
Mesoderm
The bone derives from what germ layer?
Mesoderm
The connective tissue derives from what germ layer?
Mesoderm
The serous linings of body cavities derives from what germ layer?
Mesoderm
The spleen derives from what germ layer?
Mesoderm
The cardiovascular structures derives from what germ layer?
Mesoderm
The lymphatics derives from what germ layer?
Mesoderm
The blood derives from what germ layer?
Mesoderm
The wall of gut tube derives from what germ layer?
Mesoderm
The wall of bladder derives from what germ layer?
Mesoderm
The urethra derives from what germ layer?
Mesoderm
The vagina derives from what germ layer?
Mesoderm
The kidneys derives from what germ layer?
Mesoderm
The adrenal cortex derives from what germ layer?
Mesoderm
The dermis derives from what germ layer?
Mesoderm
The gonads (ovaries and testes) derives from what germ layer?
Mesoderm
The nucleus pulposus derives from what germ layer?
Mesoderm (remnant of notochord)
The gut tube epithelium derives from what germ layer?
Endoderm
The lungs derives from what germ layer?
Endoderm
The liver derives from what germ layer?
Endoderm
The gallbladder derives from what germ layer?
Endoderm
The pancreas derives from what germ layer?
Endoderm
The eustachian tube derives from what germ layer?
Endoderm
The thymus derives from what germ layer?
Endoderm
The parathyroid derives from what germ layer?
Endoderm
The follicular cells of thyroid derives from what germ layer?
Endoderm
The luminal epithelial derivatives derives from what germ layer?
Endoderm
Define agenesis (organogenesis).
Absent organ due to absent primordial tissue
Define aplasia (organogenesis).
Absent organ despite present primordial tissue
Define deformation (organogenesis).
Extrinsic disruption; occurs after embryonic period
Define hypoplasia (organogenesis).
Incomplete organ development; primordial tissue present
Define malformation (organogenesis).
Intrinsic disruption; occcurs during embryonic period
Before week 3, teratogens tend to exert […] effects on the zygote.
Before week 3, teratogens tend to exert all-or-none effects on the zygote.
After week 8, teratogens tend to exert […] effects on the fetus.
After week 8, teratogens tend to exert growth and function effects on the fetus.
The following effects are characteristic of what teratogen: renal damage
ACE inhibitors
The following effects are characteristic of what teratogen: absence of digits (and multiple varied anomalies)
Alkylating agents
The following effects are characteristic of what teratogen: CN 8 toxicity
Aminoglycosides
The following effects are characteristic of what teratogen: neural tube defects, craniofacial defects, fingernail hypoplasia, developmental delay, IUGR
Carbamazepine
The following effects are characteristic of what teratogen: vaginal clear cell adenocarcinoma, congenital Mullerian anomalies
Diethylstilbestrol (DES)
The following effects are characteristic of what teratogen: neural tube defects
Folate antagonists
The following effects are characteristic of what teratogen: Ebstein’s anomaly
Lithium
What is Ebstein’s anomaly?
Atrialized right ventricle
The following effects are characteristic of what teratogen: fetal hydantoin syndrome
Phenytoin
Diagnose: in newborn: microcephaly, dysmorphic craniofacial features, hypoplastic nails and distal phalanges, cardiac defects, IUGR, mental retardation
Fetal hydantoin syndrome
The following effects are characteristic of what teratogen: discolored teeth
Tetracyclines
The following effects are characteristic of what teratogen: limb defects (flipper limbs)
Thalidomide
The following effects are characteristic of what teratogen: neural tube defects (inhibition of maternal folate absorption)
Valproate
The following effects are characteristic of what teratogen: bone deformities, fetal hemmorhage, abortion, ophthalmologic abnormalities
Warfarin
The following effects are characteristic of what teratogen: fetal alcohol syndrome
Alcohol
The following effects are characteristic of what teratogen: abnormal fetal development, placental abruption, fetal stimulant addiction
Cocaine
The following effects are characteristic of what teratogen: preterm labor, placental problems, IUGR, ADHD
Tobacco
The following effects are characteristic of what teratogen: congenital goiter
Iodide (lack)
The following effects are characteristic of what teratogen: congenital hypothyroidism
Iodide (excess)
The following effects are characteristic of what teratogen: caudal regression syndrome, congenital heart defects, neural tube defects
Maternal diabetes
The following effects are characteristic of what teratogen: spontaneous abortion, cleft palate, cardiac abnormalities
Vitamin A (excess)
The following effects are characteristic of what teratogen: microcephaly, mental retardation
X-rays
What is the etiology of fetal alcohol syndrome?
Maternal consumption of alcohol during pregnancy
Diagnose: mental retardation, pre- and post-natal developmental retardation, microcephaly, holoprosencephaly, facial abnormalities, limb dislocation, heart and lung fistula
Fetal alcohol syndrome
What is the leading cause of congenital malformations in the US?
Fetal alcohol syndrome
Dizygotic twins arise from […] egg(s) and […] sperm.
Dizygotic twins arise from 2 egg(s) and 2 sperm.
Monozygotic twins arise from […] egg and […] sperm.
Monozygotic twins arise from 1 egg and 1 sperm.
What percent of twins are monozygotic?
20%
What percent of twins are dizygotic?
80%
How many chorions and amnions develop when a zygote splits between Day 0-4?
2 chorions, 2 amnions
How many chorions and amnions develop when a zygote splits between Day 4-8?
1 chorion, 2 amnions
How many chorions and amnions develop when a zygote splits between Day 8-12?
1 chorion, 1 amnion
How many chorions and amnions develop when a zygote splits after Day 12?
1 chorion, 1 amnion, conjoined twins
What is the purpose of the placenta?
Primary site of nutrient and gas exchange between fetus and mother
List the fetal components of the placenta.
Cytotrophoblast, syncytiotrophoblast
List the materal components of the placenta.
Dedicua basalis
The cytotrophoblast forms the […] layer of the chorionic villi.
The cytotrophoblast forms the inner layer of the chorionic villi.
The syncytiotrophoblast forms the […] layer of the chorionic villi.
The syncytiotrophoblast forms the outer layer of the chorionic villi.
What part of the placenta secretes hCG?
Syncytiotrophoblast
hCG is structurally similar to what maternal hormone?
LH
Identify 1
chorionic villi
Identify 2
uterine artery and vein
Identify 3
maternal blood in intervillus space
Identify 4
uterus
Identify 5
placenta
Identify 6
umbilical artery
Identify 7
umbilical vein
Identify 8
amnion
Identify 9
chorion
Identify 11
amniotic fluid
There are […] umbilical arteries and […] umbilican veins in a normal umbilical cord.
There are 2 umbilical arteries and 1 umbilican veins in a normal umbilical cord.
The umbilical vein drains into the […] via the […].
The umbilical vein drains into the IVC via the ductus venosus.
The umbilical arteries carry […] blood from the […] arteries to the […].
The umbilical arteries carry deoxygenated blood from the fetal internal illiac arteries to the placenta.
The umbilical vein carries […] blood from the […] to the […].
The umbilical vein carries oxygenated blood from the placenta to the fetus.
Umbilical arteries and veins are derived from the […].
Umbilical arteries and veins are derived from the allantois.
Diagnose: urine discharge from umbilicus
Patent urachus
What are the characteristic signs and symptoms of vesicourachal diverticulum?
Outpouching of bladder into umbilicus
Diagnose: meconium discharge from umbilicus
Vitelline fistula
What is the etiology of Meckel’s diverticulum?
Failure of vitelline duct to close
Diagnose: in newborn: melena, periumbilical pain, ulcer
Meckel’s diverticulum
What is the etiology of vesicourachal diverticulum?
Failure of urachus to obliterate
What is the etiology of patent urachus?
Failure of urachus to obliterate
What is the etiology of vitelline fistula?
Failure of vitelline duct to close
The 1st aortic arch forms the […] artery.
The 1st aortic arch forms the maxillary artery.
[1st arch is maximal]
The 2nd aortic arch forms the […] artery.
The 2nd aortic arch forms the stapedial and hyoid artery.
[Second = Stapedial]
The 3rd aortic arch forms the […] artery.
The 3rd aortic arch forms the common and internal carotid artery.
The 4th aortic arch forms the […] artery.
The 4th aortic arch forms the adult aortic arch and subclavian artery.
[4th arch (4 limbs) = systemic]
The 6th aortic arch forms the […] artery and […].
The 6th aortic arch forms the pulmonary artery and ductus arteriosus.
The 5th aortic arch forms the […] artery.
The 5th aortic arch forms the nothing - it degenerates artery.
The branchial (or pharyngeal) apparatus is composed of […].
The branchial (or pharyngeal) apparatus is composed of clefts, arches, and pouches.
The branchial clefts derives from what germ layer?
ectoderm
The branchial arches derives from what germ layer?
mesoderm, neural crest ectoderm
The branchial pouches derives from what germ layer?
endoderm
The external auditory meatus derives from what branchial precursor?
1st cleft
What is the etiology of persistent cervical sinus?
Abnormal persistence of branchial cleft cyst
What are the characteristic signs and symptoms of persistent cervical sinus?
Cyst in lateral neck
The Meckel’s cartilage derives from what branchial precursor?
1st arch
The mandible derives from what branchial precursor?
1st arch
The malleus derives from what branchial precursor?
1st arch
The manibular ligament derives from what branchial precursor?
1st arch
The muscles of mastication derives from what branchial precursor?
1st arch
The mylohoid derives from what branchial precursor?
1st arch
The tensor tympani derives from what branchial precursor?
1st arch
The tensor veli palantini derives from what branchial precursor?
1st arch
The CN 5.2, 5.3 derives from what branchial precursor?
1st arch
What is the etiology of Treacher Collins syndrome?
1st arch neural crest fails to migrate
What are the characteristic signs and symptoms of Treacher Collins syndrome?
mandibular hypoplasia, facial abnormalities
The Reichert’s cartilage derives from what branchial precursor?
2nd arch
The stapes derives from what branchial precursor?
2nd arch
The incus derives from what branchial precursor?
1st arch
The styloid process derives from what branchial precursor?
2nd arch
The stylohyoid ligament derives from what branchial precursor?
2nd arch
The lesser horn of hyoid derives from what branchial precursor?
2nd arch
The muscles of facial expression derives from what branchial precursor?
2nd arch
The stapedius derives from what branchial precursor?
2nd arch
The stylohyoid derives from what branchial precursor?
2nd arch
The CN 7 derives from what branchial precursor?
2nd arch
The greater horn of hyoid derives from what branchial precursor?
3rd arch
The stylopharyngeus derives from what branchial precursor?
3rd arch
What is the etiology of congenital pharyngo-cutaneous fistula?
Persistence of 3rd branchial cleft and pouch
Diagnose: fistula between tonsillar area, cleft in neck
Congenital pharyngo-cutaneous fistula
The thyroid catrilage derives from what branchial precursor?
4th-6th arches
The cricoid cartilage derives from what branchial precursor?
4th-6th arches
The arytenoid cartilages derives from what branchial precursor?
4th-6th arches
The corniculate derives from what branchial precursor?
4th-6th arches
The cuneform derives from what branchial precursor?
4th-6th arches
The pharyngeal constrictor muscles derives from what branchial precursor?
4th arch
The cricothyroid muscle derives from what branchial precursor?
4th arch
The levator veli palantini derives from what branchial precursor?
4th arch
The intrinsic muscles of larynx (except cricothyroid) derives from what branchial precursor?
6th arch
The CN 10 - superior laryngel branch derives from what branchial precursor?
4th arch
The CN 10 - recurrent laryngeal branch derives from what branchial precursor?
6th arch
The anterior 2/3 of tongue derives from what branchial precursor?
1st arch
The posterior 1/3 of tongue derives from what branchial precursor?
3rd and 4th arches
The middle ear cavity derives from what branchial precursor?
1st pouch
The eustachian tube derives from what branchial precursor?
1st pouch
The mastoid air cells derives from what branchial precursor?
1st pouch
The endoderm lined structures of the ear derives from what branchial precursor?
1st pouch
The epithelial lining of palantine tonsil derives from what branchial precursor?
2nd pouch
The thymus derives from what branchial precursor?
3rd pouch
The inferior parathyroids derives from what branchial precursor?
3rd pouch
The superior parathyroids derives from what branchial precursor?
4th pouch
What is the etiology of cleft lip?
Failure of fusion of maxillary and medial nasal processes (primary palate)
What is the etiology of cleft palate?
Failure of fusion of lateral palantine processes, nasal septum, and median palantine processes (secondary palate)
What is the etiology of bicornate uterus?
Incomplete fusion of paramesonephric ducts
What are the characteristic signs and symptoms of bicornate uterus?
Urinary tract abnormalities and miscarriages
Diagnose: male internal genitalia, ambiguous external genitalia until puberty
5α-reductase deficiency
What is the etiology of hypospadias?
Failure of closure of urethral folds
What is the physical defect in hypospadias?
Abnormal opening of penile urethra on ventral side of penis
What are some possible complications of hypospadias?
UTIs
What is the etiology of epispadias?
Faulty positioning of genital tubercle
What is the physical defect in epispadias?
Abnormal opening of penile urethra on dorsal aspect of penis
What are some possible complications of epispadias?
Exstrophy of the bladder
What is the inheritance pattern in 5α-reductase deficiency?
AR
What is the pathogenesis of 5α-reductase deficiency?
Inability to convert testosterone to DHT
What are the characteristic lab findings in 5α-reductase deficiency?
Normal: testosterone, estrogen
Increased: LH (or normal)
What volume defines oligohydramnios?
> 0.5 L amnionic fluid
