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107 Cards in this Set

  • Front
  • Back
What fetal landmarks are present on Day 0?
Fertilization by sperm, initiating embryogenesis
When does implantation occur?
Within week 1 (as a blastocyst)
When is the bilaminar disk present?
Within Week 2
When does the heart beat?
Week 4
When does gastrulation occur?
Week 3
When does Primitive streak, notochord and neural plate begin to form?
Week 3
When do the upper and lower limb buds form?
Week 4
When do the genitalia take form?
Week 10
What's so special about weeks 3-8 of fetal development?
Neural tube is formed
Very susceptible to teratogens
Where does fertilization occur?
The ampulla of the uterine tube
what is the acrosome reaction?
Occurs when sperm binds to zona pellucida of 2ry oocyte

Release of acrosin- helps sperm penetrate.
What does penetration of the zona pellucida elicit?
The cortical reaction
makes oocyte impermeable to other sperm
what are pronuclei?
male- from male genetic info
femail- from ovum

these fuse to form the zygote
What are the stages from zygote to blastocyst?
zygote- Day 2
2, 4, and 8 cell blastula (each cell is a totipotent blastomere)
Morula- 32 cells, inner (embryo, embryoblast) and outer (placenta, trophoblast)cell mass 32 cells
Blastocyst- Day 5
what must happen first?
where does it implant?
What happens to the trophoblast?
zona pellucida must degenerate
implants on posterior superior wall of the uterus

secretory phase of the menstrual cycle
functional layer of the epithelium

trophoblast differentiates into cyto and syncytio
Rule of 2s for 2nd week
2 germ layers- epiblast, hypoblast
2 cavities, amniotic cavity, yolk sac
2 components to placenta: cytotrophoblast, syncytiotrophoblast

The epiblast is a brecursor to ectoerm, invaginates to form primitive streak. Cells from the primitive streak give rise to bother intraembryonic mesoderm and endoderm.
What is the rule of 3s for 3rd wk?
3 germ layers (gastrula)- ectoderm, mesoderm, endoderm
what are the functions of the syncytiotrophoblast and cytotrophoblast?
Syncytio- does not divide, grows into the endometrium. produces HCG
cytotrophoblast- divides, Primary chorionic villi.
What is a blighted blastocyst and waht are the sequelae?
leads to death of the embryo, hyperplastic proliferation of the trphoblast. This leads to a hydatidiform mole.
Embryologically, where does the adenohypophysis derive from?
surface ectoderm
along with the lnes, epithelial lining and epidermis
Where does the lens of the eye derive from?
surface ectoderm
along with the adenohypophysis, epithelium
Where does the neurohypophysis derive from?
Where do CNS neurons derive from?
What derives from Neuroectoderm?
Pineal gland
Ependymal cells
Where does the pineal gland derive from?
What non-neuronal things derive from the neural crest?
parafollicular C cells of the thyroid
laryngeal cartilage
bones of the skull
What does the notochord become?
vitreous humor
What comes from gut tube?
lungs, liver, pancreas, thymus, parathyroid, thyroid, follicular cells
What are teh effects of alcohol on the fetus?
Birth defects and mental retardation, fetal alcohol syndrome
What are the effects of ACE inhibition on the fetus?
renal damage
What are the effects of cocaine on the fetus?
abnl fetal development and fetal addiction
What are the effects of Diethylstilbestrol on the fetus?
DES- vaginal clear cell adenocarcinoma
What are the effects of iodide on the fetus?
Congenital goiter or hypothyroidism
What are the effects of 13-cis-retinoic acid on the fetus?
High risk for birth defects.
What are the effects of thalidomide on the fetus?
Limb defects- flipper limbs
What are the efeects of tobacco on the fetus?
Preterm labor, placental problems, ADHD
what are the effects of warfarin on the fetus?
multiple anomalies.
What happens to the blastocyst in monozygotic twins?
The inner cell mast splits. 2 amnions develop
65% 1 chorion, 1 placenta
35% 2 chorions, 2 placenta (they can combine)
What is the allantoic duct?
like a ureter from the baby to the mom throuch the umbilicus.
What is Wharton's Jelly?
the fluid in the umbilical cord.
Where does fetal erythropoiesis occur?
Young Liver Synthesizes Blood
1. Yolk Sac (3-8wk)
2. Liver (6-30 wk)
3. Spleen (9-28 wk)
4. Bone Marrow (after 28 wks)
What are the 3 shunts of fetal circulation?
1. most blood goes from IVC through the foramen ovale and to the head
2. Deoxed blood from SVC is expelled into the pulmonary artery and ductus arteriosus to the lower body of the fetus
3. Blood entering the fetus through the umbilical vein is conducted via the ductus venosus into the IVC.
What happens at the first breath?
Decrease in pulm vasc resistance causes increase in left atrial pressure. Foramen ovale closes; Increase in 02 causaess a decrease in prostas and closure of the ductus arteriosus.

Indomethacin closes the PDA
Prostas keep it open.
What is the role of Indomethacin?
closes the PDA.
What are some viruses that cross the placenta?
Rachel Caught My Voracious Virus Crossing Her Placenta

What do the following become?
Umbilical vein
umbilical arteries
ligamentum terres
Medial umbilical ligaments
median umbilical ligament
what the crap is the urachus?
part of the allantoic duct between the bladder and the ubilicus. It can form a cyst or a sinus.
What does the truncus arteriosus give rise to?
Ascending aorta and pulmonary trunk
What does the bulbus cordis give rise to?
Smooth parts of the left (aortic vestibule) and right ventricle (conus arteriosus)
What does the primitive ventricle give rise to?
Trabeculated parts of left and right ventricle
What does the primitive atria give rise to?
Truncated parts of the left and right atria
what does the left horn of the sinus venosus give rise to?
Coronary sinus
what does the right horn of the sinus venosus give rise to?
smooth part of the right atrium
What does the right common cardinal vein and right anterior cardinal vein give rise to
What are the derivatives of the aortic arch?
1st Arch- Maxillary
2nd Arch- Stapedial artery and hyoid artery
3rd - Common Carotid (3rd letter, C)
4th - left= aortic arch. right= proximal part of the right subclavian
4th = systemic
6th- proximal part of the pulmonary arteries (on left) and ductus areteriosus
What is the branchial apparatus?
Branchial clefts, arches, and pouches
also called the pharyngeal apparatus
clefts are also called grooves.
What parts of the embryo are the following parts of the branchial apparatus:
clefts- ectoderm
arches- mesoderm, neural crest
pouches- endoderm

CAP covers outside from inside
What are the derivatives of the 1st branchial arch?
Meckel's: Mandible, Malleus, incus, sphenoMandibular ligament
Muscles of Mastication: teMporalis, Masseter, lateral and Medial pterygoids, Mylohyoid, anterior belly o fdigastric, tensor tympani, tensor veli palatini, anterior 2/3rds of the tongue.
CN V2, V3
What are the derivatives of the 2nd branchial arch?
Reichert's cartilage: Stapes, Styloid process, lesser horn of the hyoid, Stylohyoid ligament.
Muscles: Facial expression, Stapedius, Stylohyoid, posterior belly of digastric

nueral crest- bone
mesoderm - muscle
What are the derivatives of the 3rd arch?
Cartilage: greater horn of the hyoid
Muscle: stylopharyngeus
Nerve: CN IX

3 and 4 make the post. 1/3 of the tongue.
What is the maternal component of the placenta?
what is the fetal?
decidua basalis
villous chorion
What are the derivatives of the 4th arch?
Superior laryngeal nerve
muscles: most pharyngeal constrictors, cricothyroid, levator veli palatini.
Cartilage: Thyroid, cricoid, arytenoids, corniculate, cuneiform

3 and 4 make the post. 1/3rd of the tongue
What derives from the 6th branchial arch?
the intrincic muscles of the larynx
CNX recurrant laryngeal
What nerve goes with what arch?
1- V
2- VII
3- IX
4-6- X
What does the tongue derive from?
ant 2/3rds - 1 innervated by V3, taste=VII
Post 1/3rd - 3,4 innervated by taste and sensation- IX and extreme posterior - X
VII is motor
What comes from the 1st branchial cleft?
external auditory meatus
What comes from the 2nd-4th branchial clefts?
temporary cervical sinuses, obliterated by 2nd arch

If it persists, you get a cyst in the neck
How does the ear develop?
1st arch - malleus, incus and tensor tympani
2nd arch - stapedius
1st cleft - external auditory meatus
1st branchial membrane - eardrum, eustachian tube.
What does the first branchial pouch become?
Endoderm structures of the ear.
middle ear cavity, eustachian tube, mastoid air cells
What does the 2nd branchial pouch turn into?
epithelial lining of the plantine tonsil
What does the 3rd branchial pouch (dorsal wings) turn into?
Inferior parathyroids
What does the 3rd branchial pouch (ventral wings) turn into?
What does the 4th branchial pouch turn into?
The superior parathyroids
What happens when there are defects in development of the 3rd and 4th pouch?
DiGeorge syndrome-> T-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid development)
How does the thyroid develop?
The thyroid diverticulum arises from the primitive pharynx.
thyroglossal duct connects tongue to thyroid. Disappears, but may persist as pyramidal lobe of thyroid.
Foramen cecum is a remnant of thyroglossal duct.
How does a cleft lip and cleft palate form?
Cleft lip- failure of fusion of the maxillary and medial nasal process (1ry palate)

Cleft palate- failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine process (2ry palate)
What are the four places from which the diaphragm derives?
1. Septum transversum
2. Pleuroperitoneal folds
3. Body wall
4. Dorsal mesentery of esophagus

Several Parts Build Diaphragm
abdominal contents may herniate into the thorax due to incomplete development (hiatal hernia)
Where does the pancreas derive from??
ventral bud becomes the head, uncinate process, and main paincreatic duct
dorsal pancreatic bud becomes everything else- body, tail, isthmus, and accessory pancreatic duct
Where does the spleen derive from?
Spleen arises from dorsal mesentery but is supplied by artery of foregut
Where does the annular pancreas derive from?
ventral and dorsal pancreatic buds encircle the duodenum. Forms a ring of pancreatic tissue that may cause duodenal narrowing.
What does the mesonephric (wolffian) duct develop into?
Seminal vesicles
Ejaculatory Duct
Ductus deferens
What does the paramesonephric (mullerian) duct develop into?
Fallopian tube, uterus, part of the vagina
What is teh role of Mullerian inhibiting substance?
secreted by testes, suppresses the paramesonephric duct in men
androgens stimulate the development of the mesonephric duct.
What does the genital tubercle turn into?
Men - glans penis
Women- glans clit
What does the urogenital sinus become?
men- corpus spongiousum
women- Vestibular bulbs

men- bulbourethral glands (of Cowper)
women- Greter vestibular glands (of Bartholin)

men- prostate gland
women - urethral and paraurethral glands
What do the urogenital folds become?
men- Ventral shaft of the penis and penile urethra
women- labia minora
What does the labioscrotal swelling become?
men- scrote
women- labia majora
What is the most common Atrial Septal defect?
foramen secundum defect
What are teh clinical manifestations of a Coartation of the aorta?
increased blood pressure in the upper extremities
lack of femoral pulse
high risk of cerebral hemorrage
high risk of bacterial endocarditis.
Who is likely to get a patent ductus arteriosus?
premature infants
infants of moms with rubella
What keeps the PDA open?
What closes it?
Open- prosta E, intrauterine asphyxia, neonatal asphyxia
Closed- Indomethacin, ACh, Histamine, and catecholamines
What do the Vitelline veins become in the adult?
Liver and Gut

Hepatic veins and sinusoids, ductus venosus, part of the IVC, portal vein, superior mesentaric vein, inferior mesenteric vein, and splenic vein
What does the Righ umbilical vein become?
Nothing, it regresses
What does the Left Umbilical vein become?
Ligamentum terres
What do the cardinal veins become?
main arteries, kidneys, and gonads

Internal jugular, SVC, part of the IVC, common iliac, renal, gonadal, intercostal, hemiazygos, and azygos.
From where do Melanocytes derive?
Neural crest
From where do the bones of the skull derive?
Neural crest
From where doe laryngeal cartilage derive?
Neural crest
From where do odontoblasts derive?
Neural crest
From where do parafollicular C cells derive?
Neural crest
What derives from the 1st aortic arch?
What derives from the second aortic arch?
Stapedial artery and the hyoid artery
What derives from the third aortic arch?
Common carotid
What derives from the 4th aortic arch?
left- aoritc arch
right- proximal part of the subclavian
What derives from the 6th aortic arch?
proximal part of the pulmonary arteries and ductus arteriosus
What cartilage develops from the 1st branchial arch?
malleus, incus, mandible, sphenomandibular ligament
What muscles develop from the 1st branchial arch?
Muscles of mastication: temporalis, masseter, later and medial pterygoids, mylohyoid, ant. belly of the digastric,

tensor tympani, tensor veli palatini

ant. 2/3rds of the tongue