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299 Cards in this Set

  • Front
  • Back
What is the first sign of development of the respiratory system?
Formation of the laryngotracheal diverticulum in the ventral wall of the primitive foregut.
When does respiratory system development begin?
Week four.
The distal end of the laryngotracheal diverticulum enlarges to form the _____ _____.
Lung bud.
What eventually separates the laryngotracheal diverticulum from the foregut?
Tracheoesophageal folds of mesoderm.
Tracheoesophageal folds fuse at the midline to form the _____ _____.
Tracheoesophageal septum.
Tracheal epithelium and glands are derived from _____.
Endoderm.
Tracheal smooth muscle, connective tissue, and C-shaped cartilage rings are derived from _____.
Mesoderm.
Describe tracheoesophageal fistula.
An abnormal connection between the esophagus and trachea.
What two conditions is tracheoesophageal fistula associated with?
Esophageal atresia and polyhydramnios.
Tracheoesophageal fistula results from improper division of the _____ by the _____ _____.
Foregut; tracheoesophageal septum.
What are the four clinical features of tracheoesophageal fistula?
Accumulation of saliva or mucus in the nose and mouth
Episodes of gagging and cyanosis after feeding
Abdominal distention after crying
Reflex of gastric contents into lungs, causing pneumonitis
What are the two diagnostic features of tracheoesophageal fistula?
Inability to pass a catheter into the stomach
X-rays demonstrating air in the infant's stomach
During week ____ of development, bronchial buds enlarge to form primary bronchi.
Five.
What are the primordia of the bronchopulmonary segments of the lung?
Tertiary or segmental bronchi.
Visceral mesoderm covering the outside of the bronchi develops into _____ _____.
Visceral pleura.
Somatic mesoderm covering the inside of the body wall develops into _____ _____.
Parietal pleura.
Bronchial epithelium and glands are derived from _____.
Endoderm.
Bronchial smooth muscle, connective tissue, and cartilage are derived from _____ _____.
Visceral mesoderm.
Describe congenital neonatal emphysema.
An over-distention with air of one or more lobes of the lung; air can be inspired but cannot be expired.
What causes congenital neonatal emphysema?
Collapsed bronchi due to failure of bronchial cartilage development.
Describe bronchiectasis.
Congenital bronchial cysts (solitary or multiple), which may be filled with air or fluid.
What causes bronchesctasis?
Dilation of the bronchi.
In what sense is lung development heterogeneous?
Proximal pulmonary tissue will be in a more advanced period of development than distal pulmonary tissue.
In reference to lung development, why can a fetus born during the glandular period (weeks 5 to 17) not survive?
Structures involved in gas exchange are not yet formed, and respiration is not possible.
What are the two major events in the canalicular period (weeks 13 to 25)?
Respiratory bronchioles and terminal sacs (primitive alveoli) develop
Vascularization increases due to capillaries forming in the visceral mesoderm
What is the earliest period at which fetuses can survive?
Week 25.
What are the two most important factors for survival of premature infants?
Adequate vascularization and surfactant levels.
What are the four major events of the terminal sac period (week 24 to birth)?
Number of terminal sacs increases
Vascularizaion increases
Differentiation of type I and type II pneumocytes
Capillaries make contact with type I pneumocytes to permit respiration
What are type I pneumocytes?
Thin, flat cells that make up part of the blood-air barrier.
What are type II pneumocytes?
Cells which produce surfactant.
Lung development continues after birth until about age _____.
Eight.
What causes increased lung size after birth?
Increase in the number of respiratory bronchioles and terminal sacs.
What do terminal sacs develop into?
Alveolar ducts and alveoli.
What is aeration at birth?
The replacement of fluid with air in the newborn's lungs.
What causes respiratory distress syndrome (RDS)?
A deficiency or absence of surfactant (prevents lung collapse) common in premature infants and infants of diabetic mothers.
What are two treatments for respiratory distress syndrome (RDS)?
Thyroxine and cortisol stimulate surfactant production.
Describe pulmonary agenesis.
Failure of one or both lungs to develop due to absence of primordial tissue.
Describe pulmonary hypoplasia.
An incomplete development of the lungs resulting in abnormally low number or size of alveoli; common cause of neonatal death.
What four structures does the pharyngeal apparatus consist of?
Five pharyngeal arches, four pharyngeal pouches, four pharyngeal grooves, and four pharyngeal membranes.
The _____ _____ contributes greatly to the formation of the head and neck.
Pharyngeal apparatus.
The pharyngeal apparatus is first observed in week _____.
Four.
Pharyngeal arches consist of _____ _____ and _____ _____.
Somitomeric mesoderm; neural cells.
What two structures does the somitomeric mesoderm of pharyngeal arches differentiate into?
An artery (aortic arches 1-6) and muscle tissue.
What two structures do the neural crests of pharyngeal arches differentiate into?
Skeletal components and connective tissue.
Pharyngeal pouches are _____ of the endodermal lining of the foregut.
Diverticula.
Pharyngeal grooves are _____ of ectoderm between each pharyngeal arch.
Invaginations or folds.
What does pharyngeal groove 1 give rise to?
The external acoustic meatus.
What does pharyngeal membrane 1 give rise to?
The tympanic membrane.
Each pharyngeal arch has a _____ _____ associated with it.
Cranial nerve.
What is the remnant of the thyroglossal duct in an adult?
The foramen cecum.
Follicular cells of the thyroid are derived from _____.
Endoderm.
What connects the thyroid to the tongue during migration to the neck?
The thyroglossal duct.
The primordial thyroid gland, or _____ _____, is formed from the endodermal lining of the foregut.
Thyroid diverticulum.
What three papillae is the primitive tongue characterized by?
Filiform (no taste buds), fungiform (taste buds), and circumvallate (taste buds).
Where do the three tongue buds develop?
On the floor of the pharynx at pharyngeal arch 1.
What nerve innervates general sensation of the anterior two thirds of the tongue?
The lingual branch of the trigeminal nerve (CN V).
What nerve innervates taste sensation in the anterior two thirds of the tongue?
The chorda tympani branch of the facial nerve (CN VII).
Which tonsil is the pharyngeal part of the tongue characterized by?
The lingual tonsil, which along with the palatine tonsil and pharyngeal tonsil form Waldeyer's ring (protects the oral part of entry).
What are the two mesodermal swellings that form the pharyngeal part tongue?
The copula and hypobranchial eminence, which develop in the floor of the pharynx at the pharyngeal arches 2, 3, and 4.
What nerve innervates general sensation in the posterior one third of the tongue?
Glossopharyngeal nerve (CN IX).
What nerve innervates taste sensation in the posterior one third of the tongue?
Glossopharyngeal nerve (CN IX).
Which nerve supplies motor innervation of the tongue?
Hypoglossal nerve (CN XII).
The intrinsic and extrinsic muscles of the tongue are derived from _____ that migrate into the tongue region from occipital somites.
Myoblasts.
The mouth is formed by a surface depression called the _____ (lined by ectoderm) and the _____ end of the foregut (lined by endoderm).
Stomodeum; cephalic.
The stomodeum and foregut meet at the _____ _____.
Oropharyngeal membrane.
The epithelium of the oral part of the tongue, hard palate, sides of the mouth, lips, parotid gland and ducts, Rathke's pouch, and enamel of the teeth are derived from _____.
Ectoderm.
The epithelium of the pharyngeal part of the tongue, floor of the mouth, palatoglossal fold, palatopharyngeal fold, soft palate, sublingual gland and ducts, and submandibular gland and ducts are derived from _____.
Endoderm.
What three swellings form the face?
Frontonasal prominence, maxillary prominence (pharyngeal arch 1), and mandibular prominence (pharyngeal arch 1).
Bilateral ectrodermal thickenings called _____ _____ develop on the ventrolateral aspects of the frontonasal prominence.
Nasal placodes.
What structure forms from nasal placodes?
Nasal pits, then nasal sacs.
What initially separates the nasal sacs from the oral cavity?
Oronasal membrane.
After rupture of the oronasal membrane, the nasal and oral cavities are continuous via the _____ _____.
Primitive choanae.
What forms the olfactory epithelium?
Ectoderm of the nasal placode in the roof of the nasal cavity.
What three types of cells does the olfactory epithelium contain?
Sustentacular, basal, and ciliated.
What type of cell gives rise to the olfactory nerve?
Ciliated cells, which have a lifespan of 1-2 months and are continuously regenerated.
What are the three structures of the intermaxillary segment?
Philtrum of the lip
Four incisor teeth
Primary palate
The secondary palate forms from outgrowths of the maxillary prominences called _____ _____.
Palatine shelves.
The primary and secondary palate fuse at the _____ _____ to form the definitive palate.
Incisive foramen.
Describe pharyngeal fistula.
An opening from the internal tonsillar area to the external neck, generally along the anterior border of the sternocleidomastoid muscle.
What causes pharyngeal fistula?
Pharyngeal pouch 2 and pharyngeal groove 2 persist.
What causes pharyngeal cyst?
Parts of pharyngeal grooves persist, forming a cyst near the angle of the mandible.
What causes first arch syndrome?
Lack of migration of neural crest cells to pharyngeal arch 1, which results facial anomalies.
Describe Treacher Collins syndrome.
An autosomal dominant disorder characterized by craniofacial deformities. Typically presents with downward slanting eyes, micrognathia (small lower jaw), conductive hearing loss, underdeveloped zygoma (cheekbone), drooping lateral lower eyelids, and malformed or absent ears.
What causes thryoglossal duct cyst?
Parts of the thyroglossal duct persist and form a cyst; typically in the midline near the hyoid bone.
What causes anterior cleft palate?
Palatine shelves fail to fuse with the primary palate.
What causes posterior cleft palate?
Palatine shelves fail to fuse with each other and the nasal septum.
What causes anterior-posterior cleft palate?
Palatine shelves fail to fuse with primary palate, each other, and the nasal septum.
What is the most common congenital malformation of the head and neck?
Unilateral cleft lip.
What are the two main causes of cleft lip?
Maxillary prominence fails to fuse with the medial nasal prominence
Underlying somitomeric mesoderm and neural crest fail to expand, resulting in a persistent labial groove
When does the internal ear develop?
Week 4.
The internal ear develops from a thickening of the surface ectoderm called the _____ _____.
Otic placode.
The otic placode invaginates (folds into) the mesoderm adjacent to the _____ and becomes the _____ _____.
Rhombencephalon; otic vesicle.
What two portions does the otic vesicle divide into?
Utricular and saccular portions.
What four structures does the utricular portion of the otic vesicle give rise to?
Utricle
Semicircular ducts
Vestibular ganglion of CN VIII
Endolymphatic duct and sac
What is the function of the utricle?
Responds to linear acceleration and the force of gravity.
The utricle contains sensory _____ _____ and _____ of the macula utriculi.
Hair cells; otholiths.
What is the function of the semicircular ducts?
Responds to angular acceleration.
Semicircular ducts contain the sensory hair cells of the _____ _____.
Cristae ampullares.
The vestibular ganglion of CN _____ lies at the base of the _____ ______ _____.
VIII; internal auditory meatus.
Describe the endolymphatic duct and sac.
A membranous canal connecting the saccule to the utricle and terminating in a blind dilation beneath the dura. The endolymphatic sac absorbs endolymph.
What three structures does the saccular portion of the otic vesicle give rise to?
Saccule
Cochlear duct (organ of Corti)
Spiral ganglion of CN VIII
What is the function of the saccule?
Responds to linear acceleration and the force of gravity.
The saccule contains sensory _____ _____ and _____ of the macula sacculi.
Hair cells; otoliths.
The cochlear duct has pitch localization where high frequencies are detected at the _____ and low frequencies are detected at the _____.
Base; apex.
What is the fate of the mesoderm that surrounds the membranous labyrinth?
It becomes cartilaginous and then ossifies to become the bony labyrinth of the temporal bone. Some also degenerates to form the perilymphatic space.
The membranous labyrinth is suspended in the bony labyrinth by _____.
Perilymph.
Perilymph communicates with the subarachnoid space via the _____ _____.
Perilymphatic duct.
What two structures develop from Meckel's cartilage?
Malleus and incus.
Which pharyngeal arch does Meckel's cartilage rise from?
Pharyngeal arch 1.
Which pharyngeal arch does Reichert's cartilage rise from?
Pharyngeal arch 2.
Which muscle moves the malleus and what is it's innervation?
Tensor tympani muscle, which is innervated by CN V-3 (trigeminal nerve, mandibular branch).
Which muscle moves the stapes and what is it's innervation?
Stapedius muscle, which is innervated by CN VII.
What structure is the malleus attached to?
The tympanic membrane.
What structure is the stapes attached to?
The oval window of the vestibule.
The auditory tube and middle ear cavity develop from pharyngeal _____ _____.
Pouch 1.
The tympanic membrane develops from pharyngeal _____ _____.
Membrane 1.
Which two cranial nerves innervate the tympanic membrane?
CN V-3 (trigeminal, mandibular branch) and CN IX (glossopharyngeal).
The external auditory meatus develops from pharyngeal _____ _____.
Groove 1.
Which two cranial nerves innervate the external auditory meatus?
CN V-3 (trigeminal, mandibular branch) and CN IX (glossopharyngeal).
Which four cranial nerves and two cervical nerves innervate the auricle?
CN V-3, CN VII, CN IX, CN X, C-2, and C-3.
What structure does the auricle develop from?
Six auricular hillocks that surround pharyngeal groove 1.
How might the organ of Corti be damaged, leading to congenital deafness?
Exposure to the rubella virus, especially during weeks 7 and 8 of development.
What three chromosomal syndromes produce malformation of the auricles?
Down syndrome (trisomy 21)
Patau syndrome (trisomy 13)
Edwards syndrome (trisomy 18)
Atresia of the external auditory meatus is associated with what syndrome?
First arch syndrome.
What is a frequent cause of conductive deafness?
Congenital cholesteatoma (epidermoid cyst).
Describe congenital cholesteatoma.
A benign tumor in the tympanic cavity; also called an epidermoid cyst.
Development of the optic vesicle begins at day _____ with formation of the _____ _____.
22; optic sulcus.
What does the outer pigment layer of the optic cup give rise to?
The pigment layer of the retina.
What two structures does the optic vesicle invaginate to form?
A double layered optic cup and optic stalk.
What are the two layers of the optic cup?
Outer pigment layer and inner neural layer.
What is a common space of retinal detachment?
The intraretinal or potential space.
The intraretinal space separates the _____ layer of the retina from the _____ layer.
Pigment; neural.
What does the inner neural layer of the optic cup give rise to?
The neural layer of the retina (rods, cones, bipolar cells, and ganglion cells).
During what week does the choroid fissure close?
Week 7.
Closure of the choroid fissure forms what three structures?
Optic nerve (CN II), optic chiasm, and optic tract.
Hyaloid vessels are the primitive form of what artery and vein?
Central artery and vein of the retina.
What two main structures are found in the optic stalk?
Choroid fissure and axons from the ganglion cell layer.
The optic nerve (CN II) is a tract of the _____.
Diencephalon.
At what age is the optic nerve (CN II) completely myelinated?
3 months.
What type of cells myelinate the optic nerve (CN II)?
Oligodendrocytes.
The optic nerve (CN II) is invested by the meninges and is surrounded by a _____ space.
Subarachnoid.
What two muscles does the iris contain?
Dilator pupillae muscle and sphincter pupillae muscle.
What muscle does the ciliary body contain?
Ciliary muscle.
What two structures do the ciliary processes give rise to?
Aqueous humor (drains into venous circulation via the trabecular meshwork and canal of Schlemm)
Suspensory fibers of the lens (ciliary zonule)
What six structures of the eye are derived from mesoderm?
Sclera, choroid, anterior chamber, cornea, vitreous body, and extraocular muscles.
What two structures of the eye are derived from ectoderm?
Cornea and lens.
Describe coloboma iridis.
A cleft in the iris caused by failure of the choroid fissure to close during week 7 of development.
Describe persistent iridopupillary membrane.
Strands of connective tissue partially cover the pupil which would normally be reabsorbed at birth.
What are four main causes of congenital cataracts?
Rubella viral infection
Congenital syphilis
Down syndrome
Galactosemia (inability to metabolize galactose, autosomal recessive)
Congenital cataracts is an _____ of the lens, usually bilateral.
Opacity.
What is the classic triad of congenital glaucoma symptoms?
Photophobia, epiphora (excess production of tears), and blepharospasm (abnormal contraction of the eyelid).
What is the treatment for congenital glaucoma?
Trabeculectomy, or removal of the eye's trabecular meshwork to allow drainage of the aqueous humor.
Describe microphthalmia and its cause.
Small eye, usually associated with intrauterine infection from toxoplasma, rubella virus, cytomegalovirus, or herpes simplex virus.
Describe anopthalmia and its cause.
Congenital absence of one or both eyes due to failure of the optic vesicle to form.
Describe cyclopia and its cause.
A single orbit with one eye due to failure of median cerebral structures to develop.
Describe retinocele and its cause.
Herniation of the retina into the sclera, resulting from failure of the choroid fissure to close.
Describe retrolental fibroplasia and its cause.
Abnormal vascularization and formation of scar tissue seen in premature infants; oxygen-induced retinopathy.
Where does detached retina occur?
Between the outer and inner layers of the optic cup. May result from head trauma or be congenital.
Describe papilledema and its cause.
Edema of the optic disk caused by increased intracranial pressure (exerted through the subarachnoid space surrounding the optic nerve).
Describe retinitis pigmentosa.
Hereditary degeneration and atrophy of the retina. Presents with night blindness (nyctalopia).
What is the most common form of congenital abnormality of the small intestine?
Meckel's (ileal) diverticulum.
What is the cause of Meckel's (ileal) diverticulum?
Incomplete obliteration of the vitelline duct.
What is the most common abnormality of midgut rotation and fixation?
Nonrotation of the midgut.
How does nonrotation of the midgut typically present in the neonatal period?
Duodenal obstruction or midgut volvulus (twisted loop of bowel).
How does nonrotation of the midgut typically present outside the neonatal period?
Chronic abdominal pain or an abdominal emergency.
What is the cause of malrotation of the midgut?
Incomplete rotation of less than 270 degrees during weeks 5-12.
What is the symptom of malrotation of the midgut?
Chronic recurrent abdominal pain.
What four intestinal abnormalities may be observed with malrotation of the midgut?
Duodenojejunal junction is low and to the right of the normal location
Jejunum is in the upper right quadrant
Cecum is in the upper / left abdomen
Large intestine is in the left abdomen
What are two major causes of neonatal intestinal obstruction?
Jejunoileal atreasia (95%) and stenosis (5%).
Describe type I jejunoileal atresia.
A single, thin web or diaphragm blocks the intestine; 19%.
Describe type II jejunoileal atresia.
A cord of scar between the upstream and downstream ends of intestine; 31%.
Describe type III jejunoileal atresia.
A portion of the intestine is completely missing; 50%.
Describe urorectal fistula.
An abnormal connection between the urethra and the rectum.
Describe Hirschsprung's disease.
Deficiency of ganglion cells in Messiner's submucosal plexus and Myenteric plexus of Auerback which causes inability of peristalsis to push the stool beyond the aganglionic segment.
Describe imperforate anus.
Defect in which the opening to the anus is blocked and the rectum ends in a blind pouch; also known as anal atresia.
What three structures does the cranial end of the hindgut develop into?
Distal one third of the transverse colon
Descending colon
Sigmoid colon
The terminal end of the hindgut is an ectoderm-lined pouch called the _____.
Cloaca.
Simple columnar absorptive cells lining hindgut derivatives, goblet cells, and enteroendocrinecells comprising the intestinal glands are derived from _____.
Endoderm.
Lamina propria, muscularis mucosae, submucosa, inner circular and out longitudinal smooth muscles of the muscularis externa, and serosa are derived from _____ _____.
Visceral mesoderm.
Describe anal agenesis.
The anal canal ends blindly, or has a fistula that commonly opens into the perineum, vagina, or urethra.
Describe anorectal agenesis.
The rectum ends well above the anal canal, typically with a fistula to the urethra in males or vagina in females.
What causes anal or anorectal agenesis with fistula?
Incomplete separation of the cloaca by the urorectal septum.
Describe rectal atresia.
The anal canal and rectum are present, but separated by an atretic segment.
What causes rectal atresia?
Abnormal recanalization or defective blood supply.
From what two structures are all adult mesenteries derived?
Ventral mesentery and dorsal mesentery.
Describe esophageal atresia.
The esophagus ends as a closed tube when the tracheoesophageal septum deviates too far dorsally.
What two conditions is esophageal atresia commonly associated with?
Polyhydrosis (excessive amniotic fluid) and tracheoesophageal fistula.
Describe esophageal stenosis.
The lumen of the esophagus is narrowed as a result of incomplete recanalization.
In what week does the foregut form?
Week 4.
The left vagus nerve innervates the _____ surface of the stomach and the right vagus nerve innervates the _____ surface.
Ventral; dorsal.
Describe hypertrophic pyloric stenosis.
The muscle layer in the pyloric region hypertrophies (muscle cells increase in size), causing a narrow pyloric lumen that obstructs food passage.
What are two clinical signs of hypertrophic pyloric stenosis?
Projectile vomiting after feeding and palpation of a small knot at the right costal margin.
Describe type I extrahepatic biliary atresia.
Occlusion of the common bile duct.
Describe type IIa extrahepatic biliary atresia.
Obliteration of the common hepatic duct.
Describe type IIb extrahepatic biliary atresia.
Obliteration of the common bile duct and hepatic and cystic ducts.
Describe type III extrahepatic biliary atresia.
Obliteration of common, hepatic, and cystic ducts without anastomosable ducts at porta hepatis.
_____ cells and ducts are part of the exocrine pancreas while _____ cells are part of the endocrine pancreas.
Acinar; islet.
Describe annular pancreas.
A ring of pancreatic tissue that abnormally encircles the duodenum. May result in narrowing of the duodenum.
What are the four major symptoms of annular pancreas?
Fullness after eating, nausea, vomiting, and feeding intolerance in newborns.
Describe duodenal stenosis.
Incomplete recanalization of the duodenal lumen.
Describe duodenal atresia.
Congenital absence or complete closure of the duodenal lumen.
What are the three major symptoms of duodenal atresia?
Polyhydramnios, bile containing vomit, and a distended stomach.
At what week does the midgut herniate through the primitive umbilical ring?
Week 6.
Describe omphalocele.
The infant's intestines or other abdominal organs stick out of the belly button. The intestines are covered by a thin layer of tissue and can be easily seen.
Placenta is a feto-maternal organ that has two components: a fetal portion that develops from the _____ _____ and a maternal portion that develops from the _____.
Chorionic sac; endometrium.
What is the functional layer of endometrium in a pregnant woman?
Decidua.
What are the three regions of decidua?
Decidua basalis, forms the maternal portion of placenta
Decidua capsularis, superficial region overlying the conceptus
Decidua parietalis (decidua vera), all regions of the endometrium other than the implantation site
The trophoblast forms the _____ chorion.
Villous.
What is the fate of the decidua capsularis?
It degenerates at week 22 due to reduced blood supply.
What two structures are shed as part of the afterbirth?
Decidua basalis and decidua parietalis.
What does the fetal component of the placenta consist of?
The tertiary chorionic villi, derived from the trophoblast and extraembryonic mesoderm; villous chorion.
Where does the main exchange of materials between the mother and fetus take place?
Branch villi, which arise from stem villi.
What are the four layers of the placental membrane?
Syncytiotrophoblast
Cytotrophoblast
Connective tissue of villus
Endothelium of fetal capillaries
What three nutrients are synthesized by the placenta?
Glycogen, cholesterol, and fatty acids.
_____ soluble vitamins cross the placental membrane more quickly than _____ soluble vitamins.
Water; fat.
What maternal protein carries iron to the fetus?
Transferin.
What seven hormones does the placenta synthesize?
Human chorionic gonadotrophin (hCG)
Human placental lactogen (hPL)
Human chorionic thyrotropin (hCT)
Human chorionic adrenocorticotrophin (hACT)
Prolactin
Relaxin
Prostaglandins
Progesterone
The maternal surface of placenta is characterized by 15 to 20 compartments called _____, which are separated by decidual septa.
Cotyledons.
What three structures pass through the primitive umbilical ring?
Yolk sac (vitalline duct)
Connecting stalk
Allantois
What three structures does the umbilical cord contain?
Left and right umbilical arteries
Left umbilical vein
Mucous connective tissue (Whatron's jelly)
What structure does the allantois degenerate to form?
The median umbilical ligament.
At what week is the physiologic herniation of the midgut loop reduced?
Week 11.
What are three sources of amniotic fluid production?
Dialysis of maternal blood
Dialysis of fetal blood
Excretion of fetal urine
What are three paths of amniotic fluid resorption?
Fetal swallowing
Absorption into the fetal bloodstream through the gastrointestinal tract
Excess fluid removal via placenta into the maternal bloodstream
Describe complete hydatidiform mole.
A non-viable fertilized egg implants in the uterus, followed by hyperplastic proliferation of the trophoblast and cystic swelling.
What are three diagnostic aids in determining complete hydratidiform mole?
Ultrasound
Continued rise in hCG levels
Development of preeclampsia (hypertension and proteinuria)
Describe choriocarcinoma.
A malignant tumor of the trophoblast which metastasizes via the blood stream; associated with high hCG levels.
What is the major symptom of choriocarcinoma?
Repeated uterine bleeding.
What is the most common cause of premature labor and oligohydramnios?
Premature rupture of the amniochrorionic membrane.
Describe amniotic band syndrome.
Bands of amniotic membrane encircle and constrict various parts of the fetus, causing limb and craniofacial abnormalities.
What does the presence of a single umbilical artery generally indicate?
Cardiovascular abnormalities.
Describe placenta previa.
The placenta attaches close to or covers the cervix.
Describe placental abruption.
The premature separation of placenta from its implantation in the uterus.
Describe erythroblastosis fetalis.
Antibodies of the mother's blood attack those of the fetus and damage red blood cells (RBCs), stimulating increased RBC production and deployment of immature RBCs.
What causes oligohydramnios?
Fetal urinary tract anomalies.
What are the four symptoms of oligohyamnios?
Intrauterine growth retardation
Post-term pregnancy
Fetal demise
Ruptured membranes
Why does oligohydramnios cause respiratory failure?
Lungs are hypoplastic (underdeveloped) due to lack of amniotic fluid.
Describe polyhydramnios.
Excessive amniotic fluid.
What causes polyhydramnios?
Failure of the fetus to swallow and absorb amniotic fluid due to gastrointestinal disorders, neurological problems, etc.; may be related to increased fluid production in fetal lung disorders.
What are the three signs of severe polydydramnios?
Breathlessness
Abdominal pain
Swelling or bloating
In what week does development of the neural tube begin?
Week 3.
When is development of the notocord complete?
Week 4.
What are three functions of the notocord?
Directs surface ectoderm to differentiate into neuroectoderm, influencing formation of the neural tube
Induces formation of the vertebral bodies
Forms the nucleus pulposus of each intervertebral disk
When does the neural plate form?
Day 19-20.
Neural folds are the site of _____ _____ differentiation.
Neural crest.
What does the neural tube give rise to?
The central nervous system.
From what three sources is the peripheral nervous system derived?
Neural crest cells (peripheral ganglia, Schwann cells, afferent dorsal root fibers)
Neural tube (preganglionic autonomic fibers and skeletal muscle innervation)
Mesoderm (dura mater, connective tissue of nerve fibers)
When does the cranial neuropore close?
Day 24.
What does the cranial neuropore form?
Lamina terminalis.
What does failure of the cranial neuropore to close cause?
Anencephaly or occipital meningeoencephalocele.
When does the caudal neuropore close?
Day 26.
What does failure of the caudal neuropore to close cause?
Spina bifida.
Describe spina bifida.
Failure of vertebral arches to form or fuse which leads to meningeocele or meningomyelocele.
Describe meningeocele.
Meninges bulge out of the vertebral canal.
Describe meningeomyelocele.
Meginges and spinal cord bulge out of the vertebral canal.
Describe spina bifida occulta.
Some part of the vertebrae are not completely closed, but the spinal cord does not protrude.
What four structures does the neural crest form?
Melanocytes
Peripheral ganglia
Medulla of the adrenal gland
Meninges
What two abnormalities is Hirschsprung's disease associated with?
Down syndrome
Chagas disease
What are two symptoms of Hirschsprung's disease?
Fecal retention
Abdominal distention
Placodes are localized thickening of _____ _____.
Surface ectoderm.
What causes Hirschsprung's disease?
Failure of neural crest cells to migrate to the Myenteric plexus.
Placodes give rise to cells that migrate to underlying mesoderm and develop into sensory receptive organs of _____ _____ and the lens of the eye.
Cranial nerves.
What type of cell forms all CNS neurons?
Neuroblasts.
What type of cell forms all supporting cells of the CNS?
Glioblasts.
What three structures does the ventricular zone give rise to?
Ependymal cells lining the central canal and ventricles
Neurons
Glial cells
What three structures does the intermediate zone give rise to?
Gray matter
Developing alar and basal plates
Basal ganglia
What two structures does the marginal zone give rise to?
White matter
Molecular layer of the cortex underlying the pia mater
When does the spinal cord begin developing?
Day 28.
What kind of innervation are ventral columns of the spinal cord associated with?
Motor.
What kind of innervation are dorsal columns of the spinal cord associated with?
Sensory.
What two regions of the spinal cord are intermediate columns for the autonomic nervous system?
T1-L2; S2-S4.
What does the alar plate of the neural tube develop into?
The dorsal horn of the spinal cord.
What does the basal plate of the neural tube develop into?
The ventral horn of the spinal cord.
What structure is the remnant of the sulcus limitans?
Rhombois fossa.
When do the three primary brain vesicles and two associated flexures develop?
During week 4.
The prosencephalon (forebrain), associated with the optic vesicles, give rise to the _____ and _____.
Telencephalon; diencephalon.
The rhombencephalon (hindbrain) gives rise to the _____, which forms the pons and cerebellum, and the _____, or medulla oblongata.
Metencephalon; Myelencephalon.
Where is the cephalic flexure located?
Between the prosencephalon and rhombencephalon.
Where is the cerebral flexure located?
Between the rhombencephalon and future spinal cord.
When do secondary brain vesicles become visible?
Week 6.
What structure does the prosencephalon give rise to?
Lateral hemispheres.
What two structures does the mesencephalon give rise to?
Thalamus and hypothalamus.
What three structures does the rhombencephalon give rise to?
Cerebellum, pons, and medulla.
What is the most common serious birth defect seen in stillborn fetuses?
Anencephaly.
Describe the Arnold-Chiary phenomenon.
Herniation of tonsils of the cerebellum and medulla through the foramen magnum, which results in blockage of the CSF passage and hydrocephalus.
What are the three main symptoms of Arnold-Chiary phenomenon?
Dysphonia (disorder of the voice), laryngeal stridor (high pitched inspiratory wheezing), and respiratory arrest (due to stretching of CN X & XII).
What other anomaly is Arnord-Chiary phenomenon associated with?
Lumbar meningomyelocele.
Describe Dandy-Walker syndrome.
Congenital hydrocephalus associated with atresia of the outlet of the foramen Luschka and Magendie.
What four symptoms is Dandy-Walkder syndrome associated with?
Dilation of the 4th ventricle
Agenesis of the cerebellar vermis
Occipital lobe meningocele
Agenesis of the splenium of the corpus callosum
What is the most common cause of congenital hydrocephalus?
Aqueductal stenosis; may be transmitted through the cytomegalovirus or toxoplasmosis.
Communicating hydrocephalus involves an obstruction _____ to the ventricles while noncommunicating hydrocephalus involves an obstruction _____ the ventricles.
Distal; within.
What is the most severe manifestation of fetal alcohol syndrome?
Holoprosencephaly (archiencephaly).
Describe holoprosencephaly (archiencephaly).
The telencephalon contains a single ventricular cavity and the olfactory bulbs and tracts are absent; often seen in Patau syndrome (trisomy 13).
What causes holoprosencephaly (archiencephaly)?
Failure of midline cleavage of the embryonic forebrain.
Describe tethered spinal cord (filum terminale syndrome).
The spinal cord is held taut at the end, leading to progressive spinal cord damage as the spinal cord stretches.
What causes tethered spinal cord (filum terminale syndrome)?
A thick and short filum terminale.
What other condition is associated with tethered spinal cord (filum terminale syndrome)?
Lipomatous tumors or lipomyelomeningoceles.
What two symptoms are associated with tethered spinal cord (filum terminale syndrome)?
Weakness and sensory deficits in the lower extremity and a neurogenic bladder (dysfunction causing difficulty to urinate).
What is the treatment for tethered spinal cord (filum terminale syndrome)?
Transection of the filum terminale.