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Embryology 3
for final exam
| Question | Answer |
|---|---|
| The gut is suspended from the _______ wall of the ___________ by ________________ | posterior; peritoneal cavity; dorsal mesentary |
| The ventral mesentary is formed by thinning of what? | Caudal part of septum tranversum |
| how does the gut tube communicate with the yolk sac? | vitallene duct |
| What makes up the foregut (regions) | pharynx; thoracic esophagus; abdominal esophagus; stomach; superior half of duodenum |
| what makes up the midgut? (regions) | inferior half of duodedum; jejunum; illeu; cecum; appendix; ascending colon; right 2/3 transverse colon |
| What makes up the hindgut? (regions) | left 1/3 of transverse colon; descending colon; sigmoid colon; rectum |
| What accessory organs are derived from foregut? | pharyngeal pouch derivitives; lungs; liver parenchyma ad hepatic duct epithelium; gallbladder; lungs; livr parenchyma and hepatic duct epithelium; gallbladder, cystic and common bile duct; exocrine pancreatic cells, pancreatic duct epi &pancreatic endocri |
| Accessory organs derived from hindgut endoderm | urogenital and derivitives |
| what day does stomach begin to elongate? | day 26 |
| what day does stomach develop fusiform shape? | day 28 |
| what happens to stomach in week 5 | dorsal wal grows faster than the ventral wall, producing a greater and lesser curvature |
| what happens to stomach in weeks 7-8? | rotates 90 degees clockwise to that greater curvaure lies to the left, Changes left vagal trunk to anterior and rt vagal tunk to posterior. |
| the stomach ALSO rotates slightly around the | ventrodorsal axis |
| how is the lesser sac of pertonieal cavity of stomach created? | by rotation into C shape, pressing against posterior body wall. |
| greater omentum | a large suspended fold of mesogastrium |
| during fetal life, what folds of the stomach fuse? what does this obilterate? | anterior and posterior folds of the greater omentum. Oblierates lowe recess, |
| what becomes the hepatic diverticulum? | endodermal thickening of ventral duodenum on right side of stomach. |
| where does hepatic diverticulum lie and what does it give rise to | lies in relation to the inferior region of the septum transversum.gives rise to liver cords, bile canaliculi, and hepatic ducts of the liver. |
| stroma of the liver is derived from | splanchnopleuric mesoderm |
| what forms liver sinusoids? | Epithelial liver cords intermingle with the vitelline and umbilical veins in this region |
| The mesoderm of the septum transversum between the liver and the foregut and the liver and the abdominal wall becomes membranous, forming the | lesser omentum and falciform ligament |
| what structures form the ventral mesogastrium? | lesser omentum and falciform ligament |
| area of the liver not covered by peritoneum is called | bare area of the liver |
| what becomes the bile duct? | connection between liver and gut. |
| what becomes the gallbladder and cystic duct? | ventral outgrowth of the bile duct |
| pancreas is formed by | dorsal and ventral pancreatic buds. |
| when do the two buds fuse to form pancreas | late wk 6 |
| what does dorsal bud of pancreas become | head, body and tail, |
| what does ventral bud of pancreas become? | uncinate process |
| what does the dorsal mesogastrium form in week 5 | Spleen |
| rotation of the dorsal mesogastrium creates the ________ between the dorsal body wall and the spleen | splenorenal (lienorenal) ligament |
| what is the dorsal mesogastrium called when between the stomach and spleen | gastrosplenic ligament |
| what is the spleen involved in in the early stages? | hemoatopoiesis (blood formation) |
| the midgut forms a dorsoventral hairpin fold in the 5th week. What is it called? | primary intestinal loop |
| the cranial limb f the interstinal loop consists mostly of | ileum |
| caudal limb of intestinal loop is what? | transverse colon. |
| what forces the midgut loop to herniate into the umbilicus? | elongation and expansion of abdominal organs. |
| in the 10th week, what happens to midgut? | retracts into abdomen, rotates counter clock. |
| what happens to ascending and descending colon in 10-11 week | becomes seondary retoperitoneal. |
| what remains intraperitoneal in midgut | transverse colon |
| what fuses to form urorectal septum? | superior Tourneaux fold and two lateral Rathke folds from cloaca |
| what process separates the posterior anorectal canal and the anterior urogenital sinus. | urorectal septum |
| when does the endodermal epithelium in the gut proliferates and completely occludes the lumen of the gut | week 6 |
| what develops into submuscosa and smooth muscle of gut tube? | mesoderm surrounding endodermal tube |
| What Arise from the intermediate mesoderm | nephric structure, portions of the gonads, male gential duct system |
| what neprhic structures will develop in cranial to caudal sequence? | cervical nephrotomes, mesonephroi, metanephroi (definitive kidneys) |
| no more than how many mesonephric tubules are present at any one time? | 30 |
| the nephric elements consist of | Bowmans Capsule and Mesonephric tubule, Glomerulus, medonephric duct |
| what is Glomerulus? | a knot of capillaries on branches sprouting from the dorsal aorta |
| what does mesonephric tubules fuse with | mesonephric ducts |
| what week do the mesonephric tubules stop working and regress? | week 10, mostly. But some remains in males to become some of genetal duct system |
| what has ureteric buds sprout from the distal mesonephric ducts on day 28 and push into the sacral intermediate mesoderm (the metanephric blastema) | metanephroi |
| the uteric bud forms | ureters and collecting ducts |
| the metanephric blastema forms | nephrons |
| what week do the metanephroi begin to function? | week 10 |
| what is the fetal kidneys prinicpal function | supplement the amniotic fluid |
| what is the placenta responsible for? | for clearing waste products from the blood. |
| The definitive renal architecture is created when? | between weeks 5-15 |
| The “ascent” of the kidneys begins when | weeks 6-9 |
| what abnormalitie can occur with the ascending of the kidneys? | "pelvic kidney", "horseshoe kidney" |
| After division of the cloaca, the anteriorly-located primitive urogenital sinus can be divided into: | 1. presumptive bladder 2. narrow neck called pelvic urethra 3. defintive urogenital sinus |
| The pelvic urethra in males will become | the membranous and prostatic urethra |
| in males, the definitive urogenital sinus will become | the penile urethra. |
| The pelvic urethra in females will become | the membranous urethra |
| in females, the definitive urogenital sinus will become | the vestibule of the vagina. |
| While the cloaca is being divided, the distal mesonephric ducts and the attached ureteric ducts are incorportated into the | posterior wall of the presumptive bladder by exstrophy |
| what type of tissue is associated with the hidgut formig the sooth musce of the bladder wall in week 12 | Splanchnopleuric mesoderm |
| The triangular area of exstrophied ducts becomes | the trigone of the bladder |
| what form primitive sex cords? | Cells of the mesonephros and coelomic epithelium invade the mesenchyme to form them |
| The paramesonephric (Mullerian) ducts begin to form during week | six |
| . In both males and females there are gonads composed of | germ cells and primitive sex cords, mesonephric ducts, and paramesonephric ducts. |
| The paramesonephric (Mullerian) ducts begin to form during week 6 by invagination of | a ribbon of coelomic epithelium from T3 to the posterior wall of the urogenital sinus. |
| Male development is triggered by the presence of | a sex-determining region of the Y chromosome |
| . SRY protein induces | medullary cells of the gonad to form testis or medullary cords. |
| In the fourth month, the testis cords are continuous with | the rete testis. |
| Testis cords are composed of | primitive germ cells and Sertoli cells |
| sertoli cells are derived from | surface of epithelium of the gland |
| Leydig cells derived from | the original mesenchyme of the gonad |
| testis cords at puberty form | seminiferous tubules. |
| what becomes the ductus deferens? | testis cords + rete testis + ductuli efferentes + mesonephric duct |
| do the paramesonephric ducts disappear? | yes |
| what triggers female development of the gonad | factors on the female sex chromosome |
| The medullary part of the gonad disappears and is replaced by | a vascular stroma. |
| The cortical cells form cortical cords which eventually form | oogonia surrounded by folliclar cells |
| do the mesonephric ducts dissapear in females | yes esentially. |
| what do the paramesonephric ducts form? | the oviducts and uterus and the upper vagina. |
| The sinuvaginal bulbs of the urogenital sinus become | lower portion of the vagina. |
| what does the hymen separate? | The lumen of the vagina and the urogenital sinus |
| explain formation of female external genitialia | the cloacal folds, develop on either side of the cloacal membrane. form a genital tubercle. folds divide into urogenital folds with the urogenital membrane and the anal folds with the anal membrane.New swellings, the genital or labioscrotal swellings, de |
| in what month does externa genitalia differentiate according to sex of individual | 4th Month |
| In the female, the urethral folds become | labia minora |
| in female, the genital tubercle becomes | clitoris |
| In female, the genital swellings will become | labia majora |
| In male, the urethral folds become | penile urethra, |
| In males, the genital tubercle becomes | the plallus |
| in males, genital swellings become | the scrotum |
| in the male, the gonads desend from | T10 level into scrotum via inguinal canal |
| when is the desent of testis completed by | 33 weeks |
| In the female, the ovary descends to | to level of the uterus |
| gubernaculum | A condensation of tissue under the serous peritoneal membrane in the fascia of both males and females |
| In the female, the gubernaculum forms | the round ligament of the uterus and the ligament of the ovary. |
| the gubernaculum in males | is attached to the gonad at one end and to the fascia of the abdominal muscles at the other, but extending to the scrotum in the male later. |
| The equivalent of the gill apparatus is referred to as | pharyngeal arches |
| Each embryonic pharyngeal arch is made up of: | 1. a mesodermal core 2. external ectodermal lining 3. internal endodermal lining 4. a central cartilaginous skeletal element 5. a striated muscle anlagen 6. a cranial nerve 7. an aortic arch artery |
| there are how many human pharyngeal arches that correspond to branchial arches 1,2,3,4 and 6 of ancient fishes? | 5 |
| pharyngeal arches form in what sequence? | cranial to caudal |
| what do the differentiation of structures in the pharygeal arches depend on? | epithelial-mesenchymal interactions, FGF’s for outgrowth and sonic hedgehog (SHH) and WNT’s for patterning. |
| The first 3 arch cartilages are developed from | neural crest cells |
| cartilages of arches 4 and 6 are developed from | lateral plate mesoderm |
| are the bones derived from the cartilages endochondral? | yes, but some become encased in membrane bones |
| Pharyngeal Arch 1: develops as pairs of what kind of swellings? | maxillary and mandibular |
| upper and lower jaws derived from | maxillary swellings ; mandibular swellings |
| palatoquadrate bar | The central cartilage of the maxillary swelling |
| The central cartilage of the mandibular swelling is | Meckel's cartilage |
| The central or dorsal end of Meckel’s cartilage will become | the malleus and incus bones of the middle ear. |
| Membrane bones that form in the maxillary process are the | premaxilla, maxilla, zygomatic bone, and squamous part of the temporal bone. |
| The temporomandibular joint forms when? | 7th and 11th week. Method is unknown, |
| what is the cartilage of the Pharyngeal Arch 2 | Reichert’s cartilage |
| what does Reicharts cartilage produce? | the stapes of the middle ear, the styloid process, the stylohyoid ligament, and the lesser horns and upper rim of the hyoid bone. |
| The cartilages of Pharyngeal arch 3 form | the greater horns and lower rim of the hyoid bone. |
| formations from Pharyngeal Arches 4 and 6 | the thyroid, cuneiform, corniculate, arytenoid, and cricoid cartilages of the larynx are formed from these arches. |
| Epiglottis is formed from where? | controversial. Some say Arch 4, others say mesoderm from elsewhere |
| Muscles that form in each arch come either from | paraxial mesoderm, somitomeres, or occipital somites. |
| Arch 1- produces | the muscles of mastication, the mylohyoid, anterior belly of the digastric, the tensor tympani, and the tensor veli palatini. |
| Arch 1 is innervated by | CN V |
| Arch 2 produces | muscles of facial expression, posterior belly of digastric, the tensor tympani, and tensor veli palatini |
| arch 2 is innervated by | CN VII |
| Arch 3 produces | stylopharyngeus |
| Arch 3 is innervated by | CN IX |
| Arch 4-6 produce | the constrictor muscles of pharynx, intrinsic muscles of larynx, the cricothyroid and the levator veli palatini |
| Arch 4-6 innervated by | CN XX |
| Pharyngeoal clefts are external grooves on the surface of the ____________. They are lined by __________ | Pharnyx, ectoderm |
| Cleft 1 becomes | external acoustic meatus |
| Reduplication of cleft 1 after it's obiliteration can produce what abnormalities? | first cleft sinus or cervical aural fistula |
| how many pharyngeal pouches do humans have as embryos? | 5 (the 6th is usually consider part of the 4th by most) |
| Pouch 1 function | forms tubotympanic recess, which becomes tympanic cavity of middle ear and auditory (eustachian) tube |
| Pouch 2 function | origin of palatine tonsil |
| Pouch 3 Function | thymus formation. Dorsal prolongations give rise to parathyroid glands |
| Pouch 4 Function | Dorsally, form superior parathyroid gland |
| why is Pouch 5 questionable ? | some consider it it's pwn pouch while others think it;s part of the 4th pouch |
| what will Pouch 5 form? | ultimobranchial bodies which attach to developing thyroid gland forming the parafollicular (C cells) of the thyroid. They secrete Calcitonin. |
| what produces parotid gland | invagination of ectoderm between maxillary and mandibular swellings |
| sublingual glands are formed from what? | endodermal lining of floor of oral cavity and paraliongual sulci |
| The face develops from how many swellings? | 5 |
| when is the face created? | between 4-10 weeks |
| name the swellings of the face | unpaired frontonasal prominance, 2 maxillary prominances, and 2 mandibular prominances |
| a pair of nasal placodes appear where? | on frontonasal prominance |
| what forms the nasal pit? | ectoderm at center of placode |
| the nasal pit separates | medial and lateral nasal prominances |
| what separates the lateral nasal prominance from the maxillary prominance | nasolacrimal groove |
| what forms nasolactrimal duct? | endoderm at floor of nasolacrimal groove invaginating. |
| what forms the bridge and septum of the nose? | the two medial nasal processes migrating together |
| The inferior tips of the medial nasal prominences form an intermaxillary segment which becomes | the philtrum of the upper lip |
| when does the buccopharyngeal membrane rupture? | day 24 |
| what forms the palate? | mostly: two palatine shelves that grow out from the maxillary prominences. But some by The intermaxillary segment |
| what form nasal cavities? | nasal pits |
| . Paranasal air sinuses develop mostly after birth or before birth? | after . |
| Maxillary sinuses appear | in 3rd month. Small at birth grow during childhood |
| Ethmoid sinuses- appear | in the 5th month and complete their growth at puberty |
| Sphenoid sinuses- appear | in the 5th postnatal month. |
| Frontal sinuses- appear | at age 5 or 6 and increase in size throughout adolescence. |
| The tongue develops as swellings of which arch? | first |
| what forms the anterior 2/3 of tongue? | lateral lingual swellings overgrowing midline (tuberculum impar) |
| What forms the midline swelling (copula) of the tongue? | arch 2 |
| the copula is overgrown by two swellings from which arch? What are those swellings called? | 3 and 4; hypopharyngeal eminance |
| what gives rise to posterior 1/3 of tongue? | hypopharyngeal eminance |
| what marks the border between the 1/3 and 2/3 of tongue? | terminal sulcas of adult tongue. |
| foraman cecum | small depression in midline of terminal sulcus |
| where is the origin of the thyroid gland? | foraman cecum |
| All the muscles of the tongue, except the palatoglossus, are formed from ________ and are Innervated by ________ | mesoderm of occipital somites; CN XII |
| palatoglossus is innervated by | CN X |
| The sensory innervation of the tongue is | anterior 2/3 by CN V3 and the posterior 1/3 by CN IX. |
| . A small part of the posterior 1/3 of tongue derived from arch 4 is innervated by | CN X’s superior laryngeal branch. |
| what develops late in week 4 as a mass of endoderm that grows at the apex of the foramen cecum. | thyroid gland |
| the thyroid reaches its adult position by week | 7 |
| The thyroid gland begins to function as early as | 10th to 12th week |
| T or F? . The thyroglossal duct may persist and produce a thyroglossal duct cyst. | True |
Created by:
tpingel