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72 Cards in this Set

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Fetal Landmarks
Day 0 - fertilization by sperm, initiating embryogenesis
Within week 1 - implantation (as a blastocyst)
Within week 2 - bilaminar disk
Within week 3 - gastrulation, primitive streak, notochord, and neural plate begin to form
Weeks 3-8 - neural tube formed, organogenesis, extremely susceptible to teratogens
Week 4 - heart begins to beat, upper and lower limb buds begin to form
Week 10 - genitalia have male/female characteristics
Embryological Rule of 2s for 2nd week
2 germ layers (bilaminar disk): epiblast, hypoblast
2 cavities: amniotic cavity, yolk sac
2 components to placenta: cytotrophoblast, syncytiotrophoblast
Rule of 3s for 3rd week
3 germ layers (gastrula): ectoderm, mesoderm, endoderm
What does surface ectoderm develop into?
adenohypophysis, lens of eye, epithelial linings, epidermis
What does neuroectoderm develop into?
neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland
What does neural crest develop into?
ANS, dorsal root ganglia, cranial nerves, melanocytes, chromaffin cells of adrenal medulla, enterochromaffin cells, pia, arachnoid, celiac ganglion, schwann cells, odontoblasts, parafollicular (C) cells of thyroid, laryngeal cartilage, bones of skull
What does mesoderm develop into?
dura mater, connective tissue, muscle, bone, cardiovascular structures, lymphatics, blood, urogenital structures, serous linings of body cavities (peritoneal), spleen, adrenal cortex, kidneys
What does endoderm develop into?
gut tube epithelium and derivitives (eg lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells)
What does the notochord develop into?
induces ectoderm to form neuroectoderm (neural plate). Forms the nucleus pulposus of the intervertebral disk
When is the embryo most susceptible to teratogens?
in 3rd-8th weeks (organogenesis) of pregnancy
How does the teratogen, Alcohol, effect a fetus?
birth defects and mental retardation, Fetal alcohol syndrome
How does the teratogen, ACE inhibitors, effect a fetus?
renal damage
How does the teratogen, Cocaine, effect a fetus?
abnormal fetal development and fetal addiction
How does the teratogen, Diethylstilbestrol (DES), effect a fetus?
Vaginal clear cell adenocarcinoma
How does the teratogen, Iodide, effect a fetus?
congenital goiter or hypothyroidism
How does the teratogen, 13-cis-retinoic acid, effect a fetus?
extremely high risk for birth defects
How does the teratogen, Thalidomide, effect a fetus?
limb defects ("flipper" limbs)
How does the teratogen, Tobacco, effect a fetus?
preterm labor, placental problems, attention-deficit hyperactivity disorder (ADHD)
How does the teratogen, Warfarin and X-rays, effect a fetus?
multiple anomalies
What is a monozygotic twin?
The splitting of a single zygote to form 2 amniotic sacs with a single common chorion and placenta or can develop 2 placentas (separate/fused) chorions and amiotic sacs
What is a dizygotic (fraternal) twin
two separate zygotes each with its own placenta, chorion and amniotic sacs
What is contained within the umbilical cord?
2 umbilical arteries (take deoxygenated blood away from fetus), 1 umbilical vein (bring oxygenated blood to fetus), 1 allantoic duct (removes nitrogenous waste from fetal bladder), Wharton's jelly (protects vessels)
What does the Truncus Arteriosus of the embryologic heart develop into?
ascending aorta and pulmonary trunk
What does the Bulbus Cordis of the embryologic heart develop into?
smooth parts of left and right ventricle
What does the Primitive Ventricle of the embryologic heart develop into?
trabeculated parts of left and right ventricle
What does the Primitive Atria of the embryologic heart develop into?
trabeculated left and right atrium
What does the Left Horn of Sinus Venosus (SV) of the embryologic heart develop into?
coronary sinus
What does the Right Horn of Sinus Venosus (SV) of the embryologic heart develop into?
smooth part of right atrium
What does the Right common cardinal vein and right anterior cardinal vein of the embryologic heart develop into?
Where and when does fetal erythropoiesis occur?
(Young Liver Synthesizes Blood)
1. Yolk Sac (3-8 wks)
2. Liver (6-30 wks)
3. Spleen (9-28 wks)
4. Bone marrow (28 wks onward)
What is the saturation of blood in the umbilical vein?
80% saturated with Oxygen
What are three important shunts in fetal circulation?
1. Foramen ovale - shunts oxygenated blood via the IVC to the aorta to the head
2. Ductus arteriosus - deoxygenated blood from SVC expelled into pulmonary artery through the ductus and into lower body of fetus
3. Ductus venosus - conducts blood from umbilical vein into the IVC
How is fetal circulation converted to infant circulation at birth?
At birth, infant takes a breath; ↓ resistance in pulmonary vasculature causes ↑ in left atrial pressure versus right atrial pressure causes foramen ovale to close
↑ in Oxygen leads to ↓ in prostaglandins, causing closure of the ductus arteriosus
What drug closes a patent ductus arteriosus (PDA)?
Indomethacin, while prostaglandins keep a PDA open
What is the postnatal derivative of the Umbilical vein?
ligamentum teres hepatis
What is the postnatal derivative of the umbilical arteries?
medial umbilical ligaments
What is the postnatal derivative of the ductus arteriosus?
ligamentum arteriosum
What is the postnatal derivative of the ductus venosus?
ligamentum venosum
What is the postnatal derivative of the foramen ovale?
fossa ovalis
What is the postnatal derivative of the Allantois?
median umbilical ligament
What is the postnatal derivative of the Notochord?
nucleus pulposis of intervertebral disk
What is a urachal cyst or sinus?
A remnant of the embryological urachus of the allantois between the blatter and the umbilicus
What are the aortic arch derivatives?
1st arch - part of the MAXillary artery
2nd arch - Stapedial (Second) artery and hyoid artery
3rd arch - common Carotid artery and proximal part of internal carotid artery
4th arch - on left, aortic arch, on right, proximal part of right subclavian artery
6th arch - proximal part of pulmonary arteries and (on left only) ductus arteriosus
What are the embryological derivatives of Branchial clefts, arches, and pouches?
Clefts = ectoderm, Arches = mesoderm, Pouches = endoderm
What are the derivatives of Branchial arch 1?
Meckel's cartilage: mandible, malleus, incus, sphenomandibular ligament
Muscles: muscles of mastication (temporalis, masseter, lateral, and medial pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini, anterior 2/3 of tongue
Nerve: CN V2 and CN V3
What are the derivatives of Branchial arch 2?
Reichert's cartilage: staples, styloid process, lesser horn of hyoid, stylohoid ligament
Muscles: muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric
Nerve: CN VII
What are the derivatives of Branchial arch 3?
Cartilage: greater horn of hyoid
Muscle: stylopharyngeus
Nerve: CN IX
What are the derivatives of Branchial arches 4-6?
Cartilage: thyroid, cricoid, arytenoids, corniculate, cuneiform
Muscles (4th arch): most pharyngeal constrictors, cricothyroid, levator veli palatini
Muscles (6th arch): all intrinsic muscles of larynx, except cricothyroid
Nerve: 4th arch - CN X (superior laryngeal branch); 6th arch - CN X (recurrent laryngeal branch)
Which branchial arches form the posterior 1/3 of the tongue?
arches 3 and 4
What are the innervations of the branchial arches?
1 - CN V2 and CN V3
2 - CN VII
3 - CN IX
4 - CN X (superior laryngeal)
6 - CN X (recurrent laryngeal)
Which cranial nerves supply taste sensation to the tongue?
CN VII, IX, and X
Which cranial nerves supply pain sensation to the tongue?
CN V3, IX, and X
Which cranial nerves provide motor sensation to the tongue?
What does the 1st branchial cleft develop into?
external auditory meatus
What does the 2-4th branchial clefts develop into?
temporary cervical sinuses which are obliterated by proliferation of the 2nd arch mesencyme, if the certical sinuses persist they can lead to a branchial cyst in the neck
What are the developmental origins of the ear?
1st branchial arch - malleus, incus, tensor tympani (V3)
2nd branchial arch - stapes, stapedius (VII)
1st cleft - external auditory meatus
1st branchial membrane - eardrum, eustachian tube
What do the branchial pouches develop into?
1st - middle ear cavity, eustachian tube, mastoid air cells
2nd - epithelial lining of palatine tonsil
3rd (dorsal wings) - inferior parathyroids
3rd (ventral wings) - thymus
4th - superior parathyroids
What is DiGeorge syndrome?
aberrant development of 3rd and 4th branchial pouches which leads to T-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid development)
How does the thyroid develop?
Thyroid diverticulum arises from the floor of the primative pharynx, descends into neck. It is connected to the tongue by thyroglossal duct, which may persist as pyramidal lobe of thyroid. The foramen cecum of the tongue is the normal remnant of the thyroglossal duct.
What is a cleft lip?
failure of fusion of the maxillary and medial nasal process (formation of the primary palate)
What is a cleft palate?
failure of fusion of the lateral palatine process, the nasal septum, and/or the median palatine process (formation of secondary palate)
What is the embryological origin of the diaphragm?
(Several Parts Build Diaphragm)
1. Septum Transversum
2. Pleuroperitoneal folds
3. Body wall
4. Dorsal mesentery of esophagus
What is the innervation of the diaphragm?
C3, 4, 5 keep the diaphragm alive
What is the embryological origin of the pancreas?
derived from the foregut
ventral pancreatic bud - pancreatic head, uncinate process, and main pancreatic duct
dorsal pancreatic bud - body, tail, isthmus, accessory pancreatic duct
What is the embryological origin of the spleen?
dorsal mesentery, but is supplied by an artery of the foregut
What is an annular pancreas?
A ring of pancreatic tissue that abnormally encircles the duodenum, may cause duodenal narrowing, caused by abnormal ventral and dorsal pancreatic bud development
What does the Mesonephric (Wolffian) ducts develop into?
SEED - Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens
What do the Paramesonephric (Mullerian) ducts develop into?
Fallopian tube, uterus, and part of the vagina
What does the genital tubercle develop into in the male and female?
male - glans penis
female - glans clitoris
What does the urogenital sinus develop into in the male and female?
male - corpus spongiosum, bulbourethral glands (cowpers), prostate gland
female - vestibular bulbs, greater vestibular glands (bartholin), urethral and paraurethral glands (skene)
What does the urogenital folds develop into in the male and female?
male - ventral shaft of penis (penile urethra)
female - labia minora
What does the labioscrotal swelling develop into in the male and female?
male - scrotum
female - labia majora