Couga Embryology

Front 1

Question

Back 1

Answer

Front 2

Describe fct of following genes:
(a) sonic hedgehog
(b) wnt-7
(c) FGF gene
(d) homeobox gene

Back 2

(a) produced at base of limbs in zone of polarizing activity. Involved in patterning along anterior ventral axis
(b) produced at apical ectodermal ridge. Necessary for proper organization along dorsal-ventral axis
(c) produced at apical ectodermal ridge. Stimulates mitosis of underlying mesodern to lengthen limbs
(d) involved in segmental organization

Front 3

Fetal landmarks:
Day 0
Within wk1
Within wk2
Within wk3
Within wk3-8
Within wk 4
Within wk 8
Within wk 10

Back 3

-Day 0: fertilization forming zygote
-Within wk1: Implantation as blastocyst
-Within wk2: Bilaminar disk (epiblast/hypoblast)
-Within wk3: Gastrulation (3 germ layers form-ectoderm, mesoderm, endoderm). Primitive streak, notocord, neural plate form.
-Within wk3-8: Neural tube formed.
-Within wk 4: Heart begins to beat. Upper and lower limb buds form.
-Within wk 8: Fetal movement (looks like a baby)
-Within wk 10: Genitalia have male/female characteristics.

Front 4

Ectopic pregnancy
(1) Most common form
(2) Most common abdominal site
(3) Risk factors
(4) Clinical signs

Back 4

(1) ampulla of uterine tube
(2) rectouterine pouch (Pouch of Douglas)
(3) Endometriosis, PID, tubular pelvic surgery, exposure to diethylstilbestrol (DES)
(4) Abnormal or brisk uterine bleed, acute abdomen, missed period, +hCG, culdocentesis showing intraperitoneal blood, +sonogram

Front 5

hCG
(1) fct
(2) how long does the corpus luteum need to persist to support pregnancy?
(3) low hCG may indicate:
(4) high hCG may indicate:

Back 5

(1) Stimulates production of progesterone by corpus luteum
(2) 8 wks
(3) ectopic pregnancy; spontaneous abortion
(4) hydatidiform mole; multiple pregnancy; gestational trophoblastic neoplasia

Front 6

Embryological derivatives of:
(1) Ectoderm
(2) Mesoderm
(3) Endoderm

Back 6

(1) Ectoderm
-Surface ectoderm: adenohypophysis (anterior pituitary); lens of eye; epithelial lining of oral cavity, ear, eye, and nose; epidermis; salivary, sweat, and mammary glands
-Neuroectoderm: Neural tube (CNS neurons, olidgodendrocytes, astrocytes, ependymal cells, pineal gland, neurohypophysis); retina; spinal cord
-Neural crest: ANS; DRG; CN's; celiac ganglion; enterochromaffin cells (adrenomedulla); parafollicular cells of thyroid; Schwann cells; pia and arachnoid; bones of skull; odontoblasts; laryngeal cartilage; aorticopulmonary septum
(2) Mesoderm: Muscle; CT; serous membranes; bone; cartilage; blood; lymph; CV organs; adrenal cortex; urogenital structures; spleen; kidney and ureter; dura mater
(3) Endoderm:
-Epithelial parts: GI tract, tonsils, thymus, pharynx, larynx, trachea, bronchi, lungs, urinary bladder, urethra, tympanic cavity, auditory tube, and pharyngeal pouches
-Parenchyma: liver, pancreas, thyroid follicular cells, parathyroids, glands of GI tract, submandibular and sublingual glands.

Front 7

Common mesodermal defects

Back 7

VACTERL
-vertebral defects
-anal atresia
-CV defects
-tracheoesophageal fistula
-renal defects
-limb defects

Front 8

Caudal dysplasia (sirenomelia)

Back 8

Constellation of syndromes ranging from minor lesions of lower vertebrae to complete fusion of lower limbs. Result of abnormal gastrulation and associated w/VACTERL.

Front 9

Teratogen effect on fetus:
(1) alcohol
(2) ACEI
(3) Cocaine
(4) Diethylstilbestrol
(5) Iodide (lack or excess)
(6) VitA (excess)
(7) Thalidomide
(8) Smoking (nicotine, CO)
(9) X rays, anticonvulsants
(10) Warfarin
(11) Tetracyclines
(12) Alkylating agents
(13) aminoglycosides
(14) Folate antagonists

Back 9

(1) alcohol: Leading cause of birth defects and mental retardation; FAS
(2) ACEI: Renal damage
(3) Cocaine: Abnormal development and addiction; placental disruption
(4) Diethylstilbestrol: vaginal clear cell adenocarcinoma
(5) Iodide (lack or excess): congenital goiter or hypothyroidism
(6) VitA (excess): high risk for spontaneous abortion and birth defect (cleft palate, CV defect)
(7) Thalidomide: limb defects (flipper limbs)
(8) Smoking (nicotine, CO): preterm labor, placental problems, IUGR, ADHD
(9) X rays, anticonvulsants: multiple anomalies
(10) Warfarin: bone deformities, hemorrhage, abortion
(11) Tetracyclines: discolored teeth
(12) Alkylating agents: absence of digits, multiple anomalies
(13) aminoglycosides: CNVIII toxicity
(14) Folate antagonists: neural tube defects

Front 10

Sacrococcygeal teratoma

Back 10

Tumor from primitive streak which normally degenerates and disappears. Contains various types of tissue due to derivation from pluripotent cells. More common in females. Usually becomes malignant during infancy and must be removed by 6mos.

Front 11

Chorion develops on day?
Amnion develops on day?

Back 11

Chorion formed day 3
Amnion formed 8

Front 12

Velamentous placenta

Back 12

Umbilical vessels abnormally travel through amniochorionic membrane before reaching placenta proper. Can rupture and cause fetal hemorrhage and death.

Front 13

Alpha Fetoprotein
(1) when does it appear?
(2) elevated AFP associated with?
(3) reduced AFP associated with?

Back 13

Fetal albumin (AFP) appears at 14-18w
Neural tube defects, omphalocele (fetal serum leaking into amniotic fluid), esophageal and duodenal atresia
Down syndrome

Front 14

Vitelline fistula

Back 14

B/w umbilicus and terminal ileum; results in fecal discharge (meconium)

Front 15

Urachal fistula

Back 15

b/w umbilicus and bladder; results in urinary discharge

Front 16

Fetal-postnatal derivatives
(1) umbilical vein
(2) Umbilical arteries
(3) ductus arteriosus
(4) ductus venosus
(5) foramen ovale
(6) allantois
(7) notochord

Back 16

(1) umbilical vein: ligamentum teres hepatis (contained in falciform ligament)
(2) Umbilical arteries: medial umbilical ligaments
(3) ductus arteriosus: ligamentum arteriosum
(4) ductus venosus: ligamentum venosum
(5) foramen ovale: fossa ovalis
(6) allantois: median ligament
(7) notochord: nucleus pulposus of intervertebral disk

Front 17

Location of fetal erythropoiesis at various stages in fetal development

Back 17

Yolk sac (3-8wk)
Liver (6-30wk)
Spleen (9-28wk)
Bone marrow (28wk+)

Front 18

Hgb synthesis at various stages in fetal development

Back 18

Delta2episolon2 (by yolk sac)
Alpha2gamma2 (by liver)
Alpha2beta2 (bone marrow)

Front 19

Adult structure derivatives of the following embryonic heart structures:
(1) Truncus arteriosus
(2) Bulbus cordis
(3) Primitive ventricle
(4) Primitive atrium
(5) Left horn of sinus venosus
(6) Right horn of sinus venosus
(7) Right common cardinal vein and right anterior cardinal vein

Back 19

(1) Truncus arteriosus: aorta; pulmonary trunk
(2) Bulbus cordis: Smooth part of RV (conus arteriosus), and LV (aortic vestibule)
(3) Primitive ventricle: trabeculated part of LV and RV
(4) Primitive atrium: Trebeculated part of RA and LA
(5) Left horn of sinus venosus: coronary sinus
(6) Right horn of sinus venosus: smooth part of RA
(7) Right common cardinal vein and right anterior cardinal vein: SVC

Front 20

Defects in the development of the aorticopulmonary septum: Cause and result.

Back 20

(1) Persistent truncus arteriosus: Abnormal migration of neural crest cells (only partial develoment of AP septum). Results in R to L shunt and cyanosis.
(2) Complete transposition of great vessels: Abnormal migration of neural crest cells and non spiral development of Ap septum. Results in R to L shunt leading to cyanosis.
(3) Tetrology of Fallot: Abnormal neural crest migration causing skewed development of AP septum. Results in: pulmonary stenosis, overriding aorta, IV septal defect, and RV hypertrophy. RtoL shunt results in cyanosis.

Front 21

Defects in development of atrioventricular septum: cause and result

Back 21

(1) univentricular heart: extremely skewed development of AV septum to right. One ventricle receives both tricuspid and mitral valves.
(2) tricuspid atresia: insufficient amnt of AV cushion tissue available for tricuspid formation. Results in agenesis of tricuspid valve so no communication b/w right atrium and ventricle. Characterized by patent foramen ovale, IV septal defect, overdeveloped left ventricle and underdeveloped right ventricle

Front 22

Defects in development of atrial septum: cause and result

Back 22

(1) Foramen secundum defect: Excessive resorption of septum primum and/or secundum. Results in opening b/w RA and LA (patent foramen ovale). Most common clinically significant ASD. If small, sx may be delayed until 30YO.
(2) Premature closing of foramen ovale: Results in hypertrophy of right side of heart and underdevelopmet of left side.

Front 23

Defects in development of ventricular septum: cause and result

Back 23

(1) ventricular septal defect: due to incomplete fusion of right bulbar ridge and left bulbar ridge and AV cushions. Results in L to R shunt and cause excessive fatigue upon exertion. L to R shunt causes increased pulmonary blood flow and pulmonary hypertension. Ultimately, pulmonary resistance becomes higher than systemic resistance and causes R to L shunt and cyanosis (termed Eisenmenger complex)

Front 24

Aortic arch derivatives:
1st arch
2nd arch
3rd arch
4 arch
5-6th arch

Back 24

1st arch: maxillary artery
2nd arch: stapedial artery and hyoid artery
3rd arch: common carotids and proximal internal carotids
4th arch: right proximal subclav and aortic arch on left
5th-6th arch: proximal pulmonary arteries and ductus arteriosus (on left)

Front 25

Neural tube defects:
(1) Spina bifida occulta
(2) Meningocele
(3) Spina bifida w/meningocele
(4) Spina bifida w/meningomyelocele
(5) Spina bifida rachischisis
(6) meningoencephalocele
(7) Meningohydroencephalocele

Back 25

(1) Spina bifida occulta: Failure of boney spinal canal to close but no herniation. Usually lower vertebral levels and evidenced by tuft of hair.
(2) Meningocele: Meninges project through spinal canal.
(3) Spina bifida w/meningocele: Meninges project through vertebral defect and form CSF filled sac. Spinal cord is normal.
(4) Spina bifida w/meningomyelocele: Meninges and spinal cord project through vertebral defect to form sac.
(5) Spina bifida rachischisis: Posterior neuropore fails to close leading to an open neural tube that lies on surface of back. Cause paralysis from level of defect caudally.
(6) meningoencephalocele: Meninges and brain protrude through skull defect. 75% death or severe mental retardation.
(7) Meningohydroencephalocele: Meninges, brain, and portion of ventricle protrude through skull defect.

Front 26

Forebrain anomalies: cause and effect
(1) Anencephaly
(2) Holoprosencephaly

Back 26

(1) Anencephaly: due to failure of anterior neuropore to close leading to failure of brain to develop. Incompatible with life. Easily diagnosed with US; increased AFP
(2) Holoprosencephaly: decreased separation of hemispheres across midline resulting in cylopia and absence of olfactory bulbs and tracts; associated with Patau's syndrome (trisomy 13) and severe FAS

Front 27

Posterior fossa malformations:
(1) Chiari Type II: clinical signs and associations
(2) Dandy-Walker: description and associations

Back 27

(1) Cerebellar tonsillar herniation through foramen magnum (affects CNIX, X, and XII) w/aqueductal stenosis and hydrocephaly. Clinical signs: spastic dysphonia, difficulty swallowing, laryngeal stridor, diminished gag reflex, apnea, vocal cord paralysis. Assoc w/syringomyelia and thoracolumbar myelomeningocele.
(2) Large posterior fossa; absent cerebellar vermis with cystic enlargement of 4th ventricle. Associated with atresia of foramen Luschka and Magendie (non comm hydrocephalus)

Front 28

Branchial Arch 1 Adult Derivatives:
(a) nerve innervation
(b) Mesoderm (not incl BV)
(c) Neural crest

Back 28

(a) CN V2 and CN V3
(b) Muscles of mastication (temporalis, masseter, lateral and medial pterygoids); mylohyoid; anterior belly of digastric; tensor tympani; tensor veli palatini; anterior 2/3 of tongue
(c)Meckel's cartilage: maxilla, zygomatic bone, aquamous portion of temporal bone, palatine bone, vomer, mandible, incus, malleus, sphenomandibular ligament

Front 29

Treacher Collins Syndrome
(a) cause
(b) result

Back 29

(a) Failure of 1st arch neural crest cells to migrate
(b) mandibular hypoplasia and facial abnormalities

Front 30

Branchial arch 2 adult derivatives:
(a) Nerve innervation
(b) Mesoderm (not incl BV)
(c) Neural crest

Back 30

(a) CNVII
(b) Muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric
(c) Reichert's cartilage: stapes, styloid process, lesser horn of hyoid, stylohyoid ligament

Front 31

Branchial arch 3 adult derivatives:
(a) nerve innervation
(b) Mesoderm (not incl BV)
(c) Neural crest

Back 31

(a) CNIX
(b) Stylopharyngeus
(c) greater horn of hyoid

Front 32

Branchial arch 4
(a) nerve innervation
(b) Mesoderm (not incl BV)
(c) Neural crest

Back 32

(a) CNX (superior laryngeal branch)
(b) Pharyngeal constrictors (except stylopharyngeus), cricothyroid, levator veli palatini
(c) none

Front 33

Branchial arch 6 adult derivatives:
(a) nerve innervation
(b) Mesoderm (not BV's)
(c) Neural crest

Back 33

(a) CNX recurrent laryngeal branch
(b) All intrinsiv muscles of larynx (except cricothyroid), upper muscle of esophagus, laryngeal cartilage
(c) none

Front 34

Branchial pouch derivatives:
Pouch 1
Pouch 2
Pouch 3
Pouch 4

Back 34

Pouch 1: Epithelial lining of eustachean tube, middle ear cavity, and mastoid air cells
Pouch 2: Epithelial lining of palatine tonsil
Pouch 3: Inferior parathyroid gland and thymus
Pouch 4: superior parathyroids

Front 35

DiGeorge's Syndrome: cause, effect, association

Back 35

Aberrant development of 3rd and 4th pouches. Leads to thymic aplasia and T cell deficiency; also hypocalcemia due to failure of parathyroid glands to develop. Assoc w/facial anomalies and CV anomalies (abnormal neural crest cell migration).

Front 36

Branchial groove derivatives

Back 36

1 becomes the external auditory meatus (the rest are obliterated)

Front 37

Branchial membrane derivatives

Back 37

1 becomes the tympanic membrane but the rest are obliterated

Front 38

Tongue development

Back 38

1st branchial arch forms anterior 2/3 (sensation from V3 and taste via CNVII)
3rd and 4th form posterior 1/3 (sensation and taste mainly via CNIX, extreme posterior CNX)
Motor innervation is CNXII

Front 39

Cause of:
(1) Cleft lip
(2) Cleft palate (anterior and posterior)

Back 39

(1) failure of the maxillary and medial nasal processes to fuse (formation of primary palate)
(2)
Anterior: palatine shelves fail to fuse with primary palate
Posterior: palatine shelves fail to fuse with each other and with nasal septum
NOTE: anteroposterior is combo of both.

Front 40

Pharyngeal fistula: cause, effect, location.

Back 40

Pouch 2 and groove 2 persist forming opening from internal tonsillar area to external neck and usually found along anterior border of the SCM muscle.

Front 41

Pharyngeal cyst: cause, effect, location

Back 41

Parts of pharyngeal groove persist usually found at angle of mandible

Front 42

General location of ectopic thymus, parathyroid, and thyroid

Back 42

Ectopic thymus/parathyroids: usually found laterally
Ectopic thyroid usually found in midline

Front 43

Thyroglossal duct cyst and lingual thyroid/cyst location

Back 43

Most commonly located at midlin near hyoid. Lingual thyroid is at the base of tongue.

Front 44

Congenital hypothyroidism (cretinism)
Cause, clinical appearance

Back 44

Due to lack of iodine, thyroid agenesis, or mutations in biosynth of thyroid hormone. Causes impaired growth and mental retardation. Flat brought nose, side set eyes, periorbital puffiness, and large protuberant tongue.

Front 45

Diaphragm:
(a) Innervation
(b) 4 parts that diaphragm is derived from

Back 45

(a) phrenic nerve (C3-5)
(b) Septum transversum (central tendon), pleuroperitoneal folds, body wall, dorsal mesentery esophagus (crura)

Front 46

Effect of incomplete diaphragm development.

Back 46

Abdominal contents may herniate into thorax leading to hypoplasia of thoracic organs (scaphoid abdomen, cyanosis)

Front 47

Adults derivatives of foregut, midgut, and hindgut

Back 47

-Foregut: Esophagus, stomach, liver, gallbladder, pancreas, upper duodenum
-Midgut: lower duodenum to proximal 2/3 of transverse colon
-Hindgut: Distal 1/3 of tranverse colon to rectum

Front 48

Clinical presentation and treatment of congenital pyloric stenosis

Back 48

Palpable mass in epigastric region and nonbilious projectile vomiting at 2wks. Treat w/surgical incision.

Front 49

Tracheoesophageal fistula: cause and effect

Back 49

Abnormal connetion b/w esophagus and trachea. Most commonly subtype is blind upper esophagus with lower esophagus connected to trachea. Results in cyanosis, choking/vomiting with feeding, air bubble on CXR, and polyhydramnios.

Front 50

Adult derivative of ventral and dorsal pancreatic buds

Back 50

Ventral bud: head of pancreas and uncinate process. Dorsal forms rest.

Front 51

Annular pancreas cause and effect

Back 51

Ventral and dorsal pancreatic buds form ring around duodenum causing obstruction.

Front 52

Adult renal derivative of the following:
(1) Pronephros
(2) mesonephros
(3) metanephros
(4) urogenital sinus
(5) ureteric bud

Back 52

(1) Pronephros: not functional and completely degenerates
(2) mesonephros: interim kidney for 1st tri; degenerates except for mesonephric (wolfian) ducts in males
(3) metanephros: permanent kidney (glomerulus to distal convoluted tubule)
(4) urogenital sinus: deveops into bladder, urethra, allantois
(5) ureteric bud: Outgrowth of mesonephric duct which gives rise to collecting duct, calyces, pelvis, ureter

Front 53

Describe potter's syndrome

Back 53

Bilateral renal agenesis leads to oligohydramnios with sequellae of limb/facial deformities, and pulmonary hypoplasia. Caused by malformation of ureteric bud.

Front 54

Describe horseshoe kidney

Back 54

Inferior poles of both kidneys fuse and are trapped under inferior mesenteric artery but kidney fct is normal.

Front 55

Adult derivatives of mesonephric duct (wollfian)

Back 55

Seminal vesicles, Epidiymis, Ejaculatory duct, Ductus deferens

Front 56

Derivatives of Paramesonephric ducts (mullerian)

Back 56

Fallopian tube, uterus, and upper 1/3 of vagina

Front 57

Describe induction of male sex

Back 57

SRY gene on y chromosome codes for testis-determining factor. MIH secreted by sertoli cells of testes which suppresses paramesonephric ducts. Increased androgens (Leydig cells) cause development of mesonephric ducts.

Front 58

Male derivatives of the following embronic structures:
(1) Genital tubercle
(2) urogenital sinus
(3) urogenital folds
(4) labioscrotal swellings

Back 58

(1) glans penis, corpus spongiosum
(2) bulbourethral glands, prostate
(3) ventral shaft of penis (penile urethra)
(4) labioscrotal swelling

Front 59

Female derivatives of the following embronic structures:
(1) Genital tubercle
(2) urogenital sinus
(3) urogenital folds
(4) labioscrotal swellings

Back 59

(1) glans clitoris, vestibular bulb
(2) greater vestibular glands (of bartholin), urethral and paraurethral Glands (of Skene)
(3) labia minora
(4) labia majora

Front 60

Cause and associations of
(1) hypospadias
(2) epispadius

Back 60

(1) Abnormal opening of penile urethra on inferior/ventral side of penis due to failure of urethral folds to close. Fix to prevent UTI
(2) Abnormal opening of penile urethra on superior/dorsal side of penis due to faulty positioning of genital tubercle. Associated with exstrophy of bladder.