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90 Cards in this Set

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Embryo

What are the fetal landmarks:
Day 0
Within week 1
Within week 2
Within week 3
Day 0: fertilization by sperm, initiating embryogenesis

Within week 1: implantation (as a blastocyst)

Within week 2: bilaminar disk (epiblast:hypblast), 2 cavities form (amniotic cavity, yolk sac), placenta is made of cytotrophoblasts and syncytiotrophoblast tissue

Within week 3: gastrulation, primitive streak, notochord, and neural plate begin to form,
Embryo

Fetal landmarks for:
Weeks 3-8
Week 4 specifically
Week 8 specifically
Week 10
Weeks 3-8: neural tube formed and organogenesis is occuring. Most suseptable to teratogens

Week 4: heart begins to beat: 4 chambers in week 4

Week 8: fetal movement; fetus looks like a baby

Week 10: genitalia have male/female characteristics
Embryo

What is the alar plate and basal plate involve in fetal development?
Alar: sensory
Basal: motor (MOW: think basal ganglion controls movement)
Embryo

What is the rule of 2's for the 2nd week of fetal development?
2 germ layers (bilaminar disk): epiblast, hypoblast
2 cavities: amniotic cavity, yolk sac
2 components to placenta: cytotrophoblast, syncytiotrophoblast
Embryo

What is the rule of 3's for the 3rd week of fetal development?
3 germ layers (gastrula): ectoderm, mesoderm, endoderm.
Embryo

What is an epiblast and what does it ultimately result in forming?
Epiblast: (precursor to ectoderm) it invaginates to form primitive streak.

Cells from the primitive streak give rise to both intraembryonic mesoderm and endoderm.
Embryo

What does the surface ectoderm form?
Surface ectoderm: adenohyophysis; lens of eye; eptithelial linings of skin, ear, eye, and nose; epidermis
Embryo

What does the neuroectoderm derive into?
Neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland.
Embryo

What does the neural crest derive into? What germ cell layer does it come from?
Ectoderm --> neural crest

ANS, dorsal root ganglia, cranial nerves, melanocytes, chromaffin cells of adrenal medulla, enterochromaffin cells, pia and arachnoid, celiac ganglion, Schwann cells, odontoblasts, parafollicular (C) cells of thyroid, laryngeal cartilage, bones of the skull.
Embryo

Endoderm forms:
Gut tube epithelium and derivatives (eg lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells)
Embryo

Notochord forms:
Induces ectoderm to form neuroectoderm (neural plate).

Its postnatal derivative is the nucleus pulposus of the intervertebral disk.
Embryo

Mesoderm forms:
Mesoderm: dura mater, connective tissue, muscle, bone, cardiovascular structures, lymphatics, blood, urogenital structures, serous linings of body cavities (eg peritoneal), spleen, adrenal cortex, kidneys.
Embryo

Mesoderm defects cause:
VACTERL:
Vertebral defects
Anal atresia
Cardiac defects
Tracheo-esophageal fistula
Renal defects
Limb defects (bone and muscle)
Embryo

Seven common congenital malformations?
1. heart defects
2. hypospadias
3. cleft lip (with or without cleft palate)
4. congenital hip dislocation
5. spina bifida
6. ancephaly
7. pyloric stenosis
Embryo

Infant with projectile vomiting Dx?
Associated with projectile vomiting
Embryo
Tetratogens

Alcohol
Birth defects and mental retardation (leading cause); fetal alcohol syndrome
Embryo

ACE inhibitors
renal damage
Embryo

Cocaine
abnormal fetal development and fetal addiction
Embryo

Diethystilbestrol (DES)
Vaginal clear cells adenocarcinoma
Embryo

Iodide
Congenital goiter or hypothyroidism
Embryo

13-cis-retinoic acid
Extremely high risk for birth defects
Embryo

Thalidomide
Limb defects ("flipper" limbs)
Embryo

Tobacco
Preterm labor, placental problems, attention-deficit hyperactivity disorder (ADHD)
Embryo

Warfarin, x-rays, anticonvulsants
Multiple anomalies
Embryo

Describe monozygotic twins
1 zygote splits evenly to develop 2 amniotic sacs with a single common chorion and placenta.
Embryo

Describe dizygotic (fraternal) and monozygotic twins can both develop:
Individual placentas, chorions, and amniotic sacs.
Embryo

Describe the umbilical cord:
Contains 2 umbilical arteries, which return deoxygenated blood from fetal internal iliac arteries, and 1 umbilical vein, which supplies oxygenated blood from the placenta to the fetus.
There is also an allantoic duct (fetal urethra), Wharton's jelly within the cord, and amniotic epithelium lining the cord.
Embryo

What is the allantoic duct? Function?
A duct within the umbilical cord that removes nitrogenous waste from fetal bladder (its like a urethra)
Embryo
What does this embryonic structure give rise to:

Truncus arteriosus
Ascending aorta and pulmonary trunk
Embryo
What does this embryonic structure give rise to:

Bulbus cordis
Smooth parts of the left and right ventricle
Embryo
What does this embryonic structure give rise to:

Primitive ventricle
trabeculated parts of the left and right ventricle
Embryo
What does this embryonic structure give rise to:

Primitive atria
Trabeculated left and right atrium
Embryo
What does this embryonic structure give rise to:

Left horn of sinus venosus
Coronary sinus
Embryo
What does this embryonic structure give rise to:

Right horn of SV
Smooth part of right atrium
Embryo
What does this embryonic structure give rise to:

Right common cardinal vein and right anterior cardinal vein
SVC
Embryo

Describe the process of fetal erythropoiesis:
Fetal erythropoiesis occurs in:
Young Liver Synthesizes Blood
1. Yolk sac (3-8wks)
2. Liver (6-30wks)
3. Spleen (9-28wks)
4. Bone marrow (28wk onward)
Embryo

What percentage of blood in umbilical vein is saturated with O2?
80%
Embryo

Describe the three important shunts in fetal circulation:
1. Foramen ovale: most oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out the aorta to the head
2. Ductus arteriosus: deoxygenated blood from the SVC is expelled into the pulmonary artery and ductus arteriosus

3. Ductus venosus: blood entering the fetus through the umbilical vein is conducted via the ductus venous into the IVC
Embryo

What is indomethacin used for?
close a PDA
Embryo
Fetal-postnatal derivatives:

Umbilical vein
ligamentum teres hepatis
Embryo
Fetal-postnatal derivatives:

Umbilical arteries
umbiLical arteries: mediaL umbilical ligaments
Embryo
Fetal-postnatal derivatives:

Ductus arteriosus
Ligamentum arteriosum
Embryo
Fetal-postnatal derivatives:

Ductus venosus
Ligamentum venosum
Embryo
Fetal-postnatal derivatives:

Foramen ovale
Fossa ovalis
Embryo
Fetal-postnatal derivatives:

Allantois
allaNtois: urachus - mediaN umbilical ligament
Embryo
Fetal-postnatal derivatives:

Notochord
Nucleus pulposus of intervertebral disk
Embryo
Fetal-postnatal derivatives:

What is the urachus?
The urachus is part of the allantoic duct (which becomes the mediaN umblical ligament) and is located between the bladder and the umbilicus
Embryo
Aortic arch derivatives:

1st part?
MAXillary a (1st is maximal)
Embryo
Aortic arch derivatives:

2nd part?
Stapedial artery and hyoid artery (Second=Stampedial)
Embryo
Aortic arch derivatives:

3rd part?
Common Carotid artery and proximal part of internal carotid a.

C = 3rd letter of the alphabet
Embryo
Aortic arch derivatives:

4th part?
On left: aortic arch
On right: proximal part of the subclavian artery

"4th arch = 4 limbs = systemic"
Embryo
Aortic arch derivatives:

6th part? (note: no fifth)
Proximal part of pulmonary arteries and (on left side only) ductus arteriosus

"6th arch = pulmonary and the pulmonary-to-systemic shunt"
Embryo

What is the branchial apparatus composed of? Derivations?
Branchial apparatus:

Composed of branchial clefts (ectoderm), arches (mesoderm and neural crests), and pouches (endoderm).

"CAP = covers outside --> inside = Clefts (ectoderm), Arches (mesoderm), Pouches (endoderm)
Embryo

Branchial arch 1 derivatives:
M's

Meckels cartilage
Mandible
Malleus
incus
sphenoMandibular ligament
Muscles of Mastication (temporalis, Masseter, lateral and Medial pterygoids)
Mylohyoid
anterior belly of digastric
tensor tympani
tensor veli palatini
anterior 2/3 tongue
Embryo

Branchial arch 2 derivatives
Reichert's cartilage: Stapes, Styloid process, lesser horn of the hyoid, Stylohyoid ligament

Muscles: muscles of facial expression, Stapedius, Stylohyoid, posterior belly of digastric

Nerve: VII
Embryo

Branchial arch 3 derivatives
Cartilage: greater horn of hyoid
Muscle: stylopharyngeus
Nerve: CN IX
Embryo

Branchial arch 4-6 derivatives
Cartilages: thyroid, cricoid, arytenoids, corniculate, cuneiform

Muscles (4th arch): most pharyngeal constrictors, cricothyroiid, levator veli palatini

Muscle (6th arch): all intrinsic muscles of larynx EXCEPT CRICOTHYROID.

Nerve:
4th arch - CN X (superior laryngeal branch)
6th arch - CN X (recurrent laryngeal branch)
Embryo

Branchial arch (1-6) innervation
Arch 1: derivatives supplied by CN V2 and V3

Arch 2: derivatives supplied by CN VII

Arch 3: derviatives supplied by CN IX

Arch 4 and 6 supplied by CN X
Embryo

Tongue development
1st brachial arch forms anterior 2/3 (thus sensation via CN V3, taste via CN VII)

3rd and 4th arches form posterior 1/3 (thus sensation and taste mainly via CN IX, extreme posterior via CN X)

Motor innervation is via CN XII

"Taste is CN 7, 9, 10 (solitary nucleus)
pain is CN V3, 9, 10
motor is CN 12"
Embryo

Branchial cleft derivatives
1st cleft develops into external auditory meatus.

2nd through 4th clefts form temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme.


Thyroglossal duct cyst in midline neck.
Embryo

What forms a branchial cyst?
Persistant cervical sinus can lead to a branchial cyst in the lateral neck.
Embyro

What forms a midline cyst in neck?
Thyroglossal duct cyst forms in the midline of the neck.
Embyro

What ear components are formed from the first arch?
first cleft?
First arch:
Malleus
Incus
tensor tyMpani (V3)

First cleft: external auditory meatus
Embryo

What ear components are formed from the second arch?
Stapes (bone)
Stapedius m. (VII)
Embryo

Branchial membranes are located at the junctions of clefts with pouches --

What derives from the first branchial membrane? (2)
Eardrum
Eustachian tube
Embryo

Branchial (pharyngeal) pouch derivatives:

1st pouch
1st pouch:
develops into middle ear cavity, eustachian tube, mastoid air cells

(contributes to endoderm-lined structures of ear)
Embryo
Branchial (pharyngeal) pouch derivatives:

2nd pouch?
2nd pouch
Develops in to epithelial lining of palatine tonsil
Embryo

Branchial (pharyngeal) pouch derivatives:

3rd pouch?
3rd pouch (dorsal wings) develops into INFERIOR parathyroids, (ventral wings) develops into THYMUS
Embryo
Branchial (pharyngeal) pouch derivatives:

4th pouch?
Develops into superior parathyroids
Embyro

What can aberrant development of 3rd and 4th pouches cause:
DiGeorge's syndrome --> leads to t-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid to develop)
Embryo:

Explain the thyroid development?
Thryoid diverticulum arises from floor of primitive pharynx, descends into neck. Connected to tongue by thyroglossal duct, which normally disappears by may persist as a pyramidal lobe of thyroid.
Embryo

What is a foramen cecum
Foramen cecum is a normal remnant of thyroglossal duct.
Embryo

Cleft lip
Failure of fusion of the maxillary and medial nasal processes (formation of primary palate)
Embryo

Cleft palate
Failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine process (formation of secondary palate)
Embryo

What are the four things that the diaphragm is derived from?
Several Parts Build Diaphragm

1. Septum transversum
2. Pleuroperitoneal folds
3. Body wall
4. Dorsal mesentery of esophagus
Embryo

Explain why the diaphragm is innervated by C3, 4, 5?
The diaphragm descends during development but maintains innervation from above C3-5.
Embryo

What is a hiatal hernia?
When there is incomplete development of the thorax that causes abdominal contents to herniate into the thorax
Embryo

Explain the derivation of the pancreas
Pancreas is derived from the foregut.

The ventral pancreatic bud becomes pancreatic head, uncinate process (lower half of head), and main pancreatic duct.

Dorsal pancreatic duct becomes everything else (body, tail, isthmus, and accessory pancreatic duct)
Embryo

Explain the derivation of the spleen:
Spleen: arises from the dorsal mesentery but is supplied by artery of the foregut.
Embryo

What is annular pancreas?
Ventral and dorsal pancreatic buds that abnormally encircle the duodenum; forming a ring of pancreatic tissue that may cause duodenal narrowing.
Embryo

Describe the embryologic derivation of the GI tract:
1. Foregut: pharynx to duodenum
2. Midgut: duodenum to transverse colon
3. Hindgut: distal transverse colon to rectum
Embryo

The kidney progresses during development until it reaches its permanent form.

What are the names of the three embryologic derivations and when in development do they appear?
1. Pronephros: week 4
2. Mesonephros: first trimester
3. Metanephros: permanent
Embryo

What does the Mesonephric (wolffian) duct develop into?
Seminal vesicles
Epididymis
Ejaculatory duct
Ductus deferens

(SEED)
Embryo

What does the Paramesonephric (mullerian) duct develop into?
Develops into fallopian tube, uterus, and part of vagina.
Embryo

What is the function of the Mullerian inhibiting substance?
Mullerian inhibiting substance secreted by testes suppresses development of paramesonephric duct in males.
Embyro

What causes the development of the mesonephritic ducts?
High androgen production
Embryo
Male vs Female development
What does each grow into?

Genital tubercle
Genital tubercle

DHT: glans penis
Estrogen: glans clitoris
Embryo
Male vs Female development
What does each grow into?

Urogenital sinus
Urogenital sinus:

DHT:
corpus spongiosum
bulbourethral glands (of Cowper)
Prostate gland

Estrogen:
vestibular bulbs
greater vestibular glands (of Bartholin)
Urethral and paraurethral glands (of Skene)
Embryo
Male vs Female development
What does each grow into?

Urogenital folds
DHT: ventral shaft of the penis (penile urethra)

Female:
Labia minora
Embryo
Male vs Female development
What does each grow into?

Labioscrotal swelling
DHT: scrotum

Estrogen: labia majora