Devt. Anat. Block C

  1. extraembryonic coelom
    • coalescence of coelomic spaces in the extraembyronic mesoderm during 2nd week of development
    • subdivides lateral mesoderm into somatic mesoderm (associated with chorion/amniotic cavity) and splanchnic mesoderm (associated with endoderm around the yolk sac)
  2. somatic mesoderm
    • outer layer of lateral mesoderm associated with chorion/amniotic cavity
    • forms parietal layers (parietal pleura, parietal pericardium & parietal peritoneum)
  3. splanchnic mesoderm
    • layers of lateral mesoderm associated with endoderm around yolk sac
    • forms visceral layers (visceral pleura, visceral pericardium, & visceral peritoneum)
  4. divisions of somatic mesoderm (3rd week)
    paraxial, intermediate, lateral
  5. intraembyronic coelom
    • coalescence of small coelomic spaces appearing in lateral mesoderm
    • divides lateral mesoderm into somatopleure (superficial ectoderm + somatic mesoderm) and splanchnopleure (endoderm + splanchnic mesoderm)
  6. splanchnopleure
    • endoderm + splanchnic mesoderm
    • forms gut & viscera (organs)
  7. somatopleure
    • superficial ectoderm + somatic mesoderm
    • forms body wall & parietal layers
  8. divisions of intraembryonic coelom
    • anterior curve: pericardial cavity
    • limbs of curve: pleural/peritoneal cavities (2)
  9. pericardial cavity
    • rostral/anterior curve of intraembryonic coelom
    • surrounds developing heart
  10. pericardioperitoneal canals
    • connect pericardial cavity with pleural/peritoneal cavity
    • dorsal to septum transversum
    • lateral to developing gut
  11. diaphragm
    • separates the pericardial & pleural cavities from the peritoneal cavity
    • formed from septum transversum (central tendon), pleuroperitoneal membranes (small dorsal portion), dorsal mesentery of esophagus (crura), body wall (peripheral edges)
  12. partitions of intraembryonic coelom
    • septum transversum
    • pleuro-pericardial membranes (2)
    • pleuro-peritoneal membranes (2)
  13. fate of dorsal mesentery
    suspends entired gut from posterior abdominal wall
  14. fate of ventral mesentery
    disappears except at most caudal region of foregut to form falciform ligament of liver
  15. source of falciform ligament of liver
    ventral mesentery
  16. formation of primitive mediastinum
    • pleuropericardial membranes fuse with mesodermal mesenchyme ventral to esophagus
    • separates pericardial cavity from pleural cavities
  17. development of diaphragm
    • septum transversum: central tendon
    • pleuroperitoneal membranes: small dorsal portion
    • dorsal mesentery of esophagus: crura of diaphragm
    • body wall: peripheral edhes (muscular ingrowth mostly on dorsal aspect)
  18. costodiaphragmatic recess
    expansion of the pleural cavities into the lateral body wall causing portion of the body wall to form peripheral parts of the diaphragm
  19. pectus excavatum
    • sunken/funnel chest
    • results from short central tendon of the diaphragm which pulls on the inferior portion of the xiphoid portion of the sterum creating a depression of the sternum & anterior chest and flaring of the costal cartilages of ribs 7-10
  20. congenital diaphragmatic hernia
    • results from failure of fusion of pleuroperitoneal membranes creating a hole (foramen of Bochdalek) posterolaterally (usually on left)
    • Morgani hernia: failure of fusion between septum transversum & lateral body wall
    • hiatal hernia: delay in descend of stomach
    • Bochdalek hernia: posterolateral defect due to failure of fusion of pleuroperitoneal membranes
    • abdominal contents in thoracic cavity, patient presents with "flat abdomen"
    • negatively affects lung development
  21. Morgani hernia
    failure of fusion between septum transversum & lateral body wall
  22. hiatal hernia
    delay in descent of stomach (keeping hiatus larger)
  23. Bochdalek hernia
    posterolateral defect due to failure of fusion of pleuroperitoneal membranes
  24. innervation of diaphragm
    • central portion: phrenic n (C3,4,5)
    • peripheral portions: lower intercostal nn
  25. embryonic layers involved in primitive gut formation
    • endoderm: gives rise to epithelium & glands
    • splanchnic mesoderm: gives rise to muscular & fibrous elements of gut tube
  26. 3 embryonic folds
    • head fold: involves mouth (stomodeum)
    • tail fold: involves anus (proctodeum)
    • lateral fold: pinches off dorsal aspect of yolk sac
  27. foregut derivatives
    pharynx, esophagus, stomach, proximal duodenum (proximal to bile duct), liver, pancreas, gallbladder
  28. arterial supply of foregut
    celiac trunk
  29. arterial supply of midgut
    superior mesenteric artery
  30. arterial supply of hindgut
    inferior mesenteric artery
  31. midgut derivatives
    small intestines (including duodenum after common bile duct), cecum, appendix, ascending colon, proximal 2/3 of transverse colon
  32. hindgut derivatives
    distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper part of anal canal
  33. tracheoesophageal fold
    fusion of two sides forms tracheoesophageal septum dividing esophagus & laryngotracheal tube
  34. esophageal atresia
    • defect in esophageal development due to malformation of tracheoesophageal septum resulting in a blind end esophagus
    • causes polyhydramnios (baby can't swallow)
  35. tracheoesophageal fistula
    malformation of the esophagus; communication between the esophagus & the respiratory tract
  36. esophageal stenosis
    • defect of esophageal development in which there is a narrowing of the esophagus
    • can lead to short esophagus & congenital hiatal hernias
  37. development of stomach
    • caudal part of foregut rotates 90* clockwise
    • dorsal border forms greater curvature (moves to left)
    • ventral border forms lesser curvature (moves to right)
    • original left side - ventral
    • original right side - dorsal
    • left vagus n: anterior vagal trunk
    • right vagus n: posterior vagal trunk
  38. pyloric stenosis
    muscular hypertrophy of gastric pylorus causes constriction of pyloric region of stomach & leads to non-bilious projectile vomiting
  39. dorsal mesogastrium
    • dorsal mesentery of the stomach
    • elongates to form greater omentum
  40. omental bursa
    • lesser sac of peritoneum
    • begins as a series of clefts in dorsal mesogastrium which coalesce forming a single cavity
  41. dorsal mesogastrium derivatives
    • greater omentum (gastrosplenic ligament, gastrophrenic ligament, gastrocolic ligament)
    • mesentery proper
    • lienorenal ligament
    • transverse mesocolon
    • mesoappendix
    • mesocecum
    • sigmoid mesocolon
    • phrenicolic ligament
  42. ventral mesogastrium derivatives
    • lesser omentum (hepatogastric & hepatoduodenal ligaments)
    • falciform ligament & ligamentum teres hepatis
  43. source of duodenum
    foregut & midgut
  44. arterial supply of duodenum
    celiac trunk & superior mesenteric artery
  45. duodenal stenosis
    partial recanalization of duodenum (parts 3 & 4) causing bilious vomit (stenosis below ampulla of Vater)
  46. duodenal atresia
    • no recanalization of duodenum
    • bilious vomit (atresia below ampulla of Vater)
    • double bubble sign: fluid building up in stomach & duodenal bulb
  47. hepatic diverticulum
    • liver bud of endoderm that grows ventrally from distal end of foregut & invades the septum transversum
    • cranial portion: liver
    • caudal portion: gallbladder
    • stalk: cystic duct & common bile duct
  48. when does liver start producing bile
    12 weeks
  49. meconium
    first few bowel movements of an infant; contain a large amount of bile (dark green)
  50. development of pancreas
    • ventral bud: uncinate process & inferior head of pancreas
    • ventral bud + distal dorsal bud: main pancreatic duct
    • proximal dorsal bud: accessory pancreatic duct
  51. annular pancreas
    defect caused when the ventral pancreatic bud surrounds the descending duodenum upon rotation & causes obstruction of the duodenum
  52. stages of midgut development
    herniation, return, fixation
  53. midgut development: herniation
    when the cranial and caudal limbs do a 90* clockwise rotation around the superior mesenteric artery
  54. midgut development: return
    • regression of mesonephros
    • reduced growth of liver
    • relatively small abdominal cavity
  55. midgut development: fixation
    • leads to fusion of layers of the greater omentum & fusion of greater omentum with transverse mesocolon
    • establishes secondarily retroperitoneal structures
  56. secondarily retroperitoneal structures
    • 2,3,4 parts of duodenum
    • pancreas
    • ascending colon
    • descending colon
  57. abnormalities of midgut rotation
    • Ileal (Meckel's) diverticulum: incomplete obliteration of vitelline duct
    • umbilicoilieal fistula
    • omphaloceoele
    • gastroschisis
  58. urogenital septum
    • fuses with cloacal membrane
    • divides cloaca into urogenital sinus & anorectal canal
    • perineal body: in between
  59. pectinate line
    divides upper 2/3 of anal canal from lower 1/3
  60. urogenital ridge
    longitudinal ridge of intermediate mesoderm that runs along dorsal aorta; pushes out from the body wall into the coelom
  61. nephrogenic cord
    part of urogenital ridge that runs the entire length of the embryo & gives rise to the urinary system
  62. pronephros
    first kidney which begins development at beginning of 4th weeks but degenerates by the end of the 4th week
  63. mesonephros
    middle kidney which begins to form at end of 4th week
  64. metanephros
    • definitive kidney; appears as small projection off mesonephric duct in 5th week
    • develops from ureteric bud (metanephric diverticulum) & metanephrogenic blastema (metanephric mass)
  65. mesonephric tubules
    • connect to mesonephric duct
    • in females: degenerate (remnants - epoophoron & paroophoron)
    • in males: develop into efferent ductules (remnant - paradidymis)
  66. mesonephric duct
    • AKA Wolffian duct
    • empties into cloaca
    • in females: degenerates (remnants - appendix vesiculosa, duct of Gartner)
    • in males: forms vas deferens, epididymis, seminal vesicles & ejaculatory duct (remnant - appendix epididymis)
  67. metanephrogenic blastema origin
    intermediate mesoderm
  68. progression of blood supply to kidney
    external iliac branches - abdominal aorta branches - renal arteries
  69. supranumery renal arteries
    multiple renal arteries can exist if arteries do not degenerate properly; can lead to hydronephrosis
  70. allantois
    connects to cloaca; constricts proximal end to form urachus
  71. urachus
    extends from the apex of the bladder to the umbilicus (median umbilical fold)
  72. cloachal membrane
    invagination of ectoderm that fuses with urorectal septum dividing area into urogenital membrane (anteriorly) & anal membrane (posteriorly)
  73. perineal body
    point where urorectal septumĀ  pushes through cloaca & makes contact w/ skin
  74. urorecal septum
    mesenchyme that pushes through & divides the cloaca into urogenial sinus & anorectal canal
  75. UG sinus derivatives
    • vesical part: forms majority of urinary bladder (both sexes)
    • pelvic part: forms entire female urethra; forms prostatic & membranous male urethra
    • penile part: forms penile (spongy) male urethra
  76. trigone of bladder
    represents portion of bladder where mesonephric ducts were incorporated; becomes overgrown by endoderm
  77. renal agenesis
    • abscence of kidney due to failure of ureteric bud to form
    • unilateral: other kidney will undergo compensatory hypertrophy
    • bilateral: incompatible with life
  78. polycystic kidneys
    kidneys are filled with cysts & nonfunctional
  79. pelvic kidney
    kidney fails to undergo ascent & remains functional
  80. horseshoer kidney
    inferior mesenteric artery causes midline obstruction; blocks complete ascent of fused kidneys
  81. ectopic ureters
    ureters end in places other than bladder (vagina, prostate, urethra)
  82. urachal abnormalities
    • cysts: improper closure of allantois in region of umbilicus
    • sinus: discharge of clear cyst fluid near umbilius
    • fistula: constant discharge of urine & cyst fluid from bladder & cyst
  83. extrophy of bladder
    incomplete closure of musculature of the abdominal wall that causes exposure & erosion of anterior wall of bladder; urine is constantly secreted
  84. development of suprarenal glands
    • cortex: mesoderm
    • medulla: ectoderm + NCC invasion
  85. chromaffin cells
    develop in medulla of suprarenal glands from NCCs
  86. congenital adrenal hyperplasia
    abnormal increase in testosterone production by adrenal glands
  87. indifferent gonads
    • undergo similar development in both male & female
    • external cortex & internal medulla
    • stage occurs in development of gonads, ducts & external genitalia
  88. paramesonephric duct
    Mullerian duct; forms alongside mesonephric duct (gonads develop medial to both ducts)
  89. AMH
    • antimullerian hormone
    • AKA mullerian inhibiting substance
    • secreted by Sertoli cells to inhibit development of paramesonephric duct, driving it to apoptosis in males
  90. TDF
    testes determining factor: present on the Y chromosome driving development in male direction
  91. Leydig cells
    interstitial cells that develop in the mesenchyme outside of primary sex cords; responsible for secretion of testosterone by the 8th week of development
  92. primary sex cords
    • inward proliferation of mesothelium into mesnchyme; colonized by PCGS
    • males: become seminiferous cords
    • females: obliterated & replaced by secondary sex cords
  93. processus vaginalis
    projection of the peritoneum that pusches down the muscle & fascia into future scrotum
  94. tunica vaginalis
    peritoneal layers that remain with testis in adult after processus vaginalis has been obliterated
  95. congenital inguinal hernia
    herniation of gut into scrotum through patent processus vaginalis (indirect hernia)
  96. cryptorchidism
    failure of testes to descend; spermatogenesis may be affected
  97. hydrocele
    presence of excess fluid in persistant process vaginalis
  98. hematocele
    presence of blood in persistant processus vaginalis; collection of blood in tunica vaginalis
  99. varicocele
    veins of pampiniform plexus are elongated & dilates (usually on left)
  100. congenitally acquired indirect hiatal hernia
    hernia occuring as an adult due to maintained connection between peritoneal cavity & tunica vaginalis (patent processus vaginalis)
  101. derivatives of indifferent gonads
    • male: testes, seminiferous tubules, rete testis, sertoli cells, leydig cells
    • female: ovary, primordial follicles, rete ovarii
  102. derivatives of gubernaculum
    • male: gubernaculum testis (testicular ligament)
    • female: round ligament of the uterus, ovarian ligament
  103. derivatives of mesonephric tubules
    • male: efferent ductules, paradidymis
    • female: epoophoron, paroophoron
  104. derivatives of mesonephric ducts
    • males: appendix epipdidymis, epididymis, ductus deferens, seminal vesicles, ejaculatory duct
    • females: appendix vesiculosa, duct of Gartner
    • both: ureter, pelvis, calices & collecting tubules
  105. derivatives of paramesonephric duct
    • male: appendix testes
    • female: uterine tubes, uterus, cervix, superior 1/3 of vagina, hydatid of Morgani
  106. derivatives of UG sinus
    • male: bladder, prostate gland, prostatic urethra, prostatic utricle, membranous urethra, bulbourethral glands, penile urethra
    • female: inferior 2/3 vagina, bladder, urethra, urethral & paraurethral glands, greater vestibular glands
  107. derivatives of sinus tubercle
    • male: seminal colliculus
    • female: hymen
  108. derivatives of genital tubercle
    • male: glans & body of penis
    • female: clitoris
  109. derivatives of urogenital folds
    • male: ventral aspect of penis
    • female: labia minora
  110. derivatives of labioscrotal swellings
    • male: scrotum
    • female: labia majora & mons pubis
Card Set
Devt. Anat. Block C
developmental anatomy block c