Basic emryology Flashcards
Separation into pleura and pericardinal cavities
pleuropericardial folds (mesoderm) appear in between developing lungs and heart grow from lateral body wall towards midline to separate pericardial cavity (ventrally) from pleural cavity (dorsally)
what forms the lower arm of the umbilical herniaton
terminal ileum, cecum, appendix, colon
canalicular period
16-26 weeks Respiratory bronchiles and some alveolar ducts start to appear (terminal sacs start to form, but not enough or mature enough). some vascularization starts to appear, but premature is infants have poor prognosis
what is the trachea made out of?
epithelium and glands are endoderm smooth muscle, connective tissue, cartilage come from splanchnic lateral plate mesoderm
Congenital diaphragmatic hernia
incomplete closure of pericardioperitoneal canals
Mesenery
formed by splanchinic mesoderm around gut tube
Liver formation
Through a hepatic diverticulum that grows in the ventral mesentery
vitelline duct
the connection to the yolk sac in the midgut to the ileum
Bild Duct
grows in ventral mesentery and rotates left 270° to enter duodenum from posterior left and fuse with pancreatic duct
ventral mesentery of liver becomes..
falciform ligmanet
mesentery between stomach and liver become…
lesser omentum This is derived from spetum trasnversum
Urethral plate in the males
is inclosed inside and reaches tip of penis by ectodermal thickening
What forms glans of clitoris?
slight elongation of genital tubercle
Genital ducts
mesonephric ( wolffian) paramesonephric ducts (mullarian)
female reproductive tract
no SRY develops ovary into Follicular cells and stromal cells no TDF means no testosterone and the mesonephric ducts regress and paramesonephric ducts persists.
how long until external genetalia are indistinguishable
week 12
urogential sinus of female
bladder, urethra, lower 2/3 of vagina, bulbourethral glands, vestibule,
Physiological herniation
when the elongation of the mid gut tube is too rapid for the growth of the body cavity and herniates out of the umbilical cord.
urogenital sinus creates…
bladder, urethra, vagina, prostate gland, and prostatic and membranous urethras in males
Foramen ovale
shunt between right and left atria
metanephric blastema produces…
formation of nephrons bowman’s capsule, convuluted tubes, loop of henle
what forms vestibule
urogential plate
paramesoneprhic ducts give rise to..
uterus, uterine tubes, upper 1/3 or vagina
allantois
membranous sac taht communicates from the urogenital sinus (and eventually bladder) to umbillicus. Forms the urachus after birth.
Septum transversum
during crano-caudal folding forms the central tendon of the diaphragm between heart and future liver. It is formed higher and descends and on the way recieves myoblasts that from the skeletal muscles of the diaphram (C3-5 with the phrenic n).
Hindgut derivatives
distal 1/3 transverse colon descending colon sigmoid colon rectum upper anal canal urogential sinus
what does the mesonephric ducts form…
epididymis and ductus deferns (rete testes, efferent ducts, seminal vesicle, trigone)
endocardial tube
vasculogenic cell clusters that line the horseshoe area above oropharyngeal membrane in splanchinic mesoderm.
renognesis
reciprocal induction of metanephric blastema and uteric bud to grow.
in male the gland of penis is formed by…
Grow of the genital tubercle
secondarily retroperitoneal viscera
pancrease dudodeum asc. colon desc. colon
In males, the scrotum is formed by…
swelling of the labioscrotal folds. their fusion forms the scrotal raphe
tracheoesophageal tube
divides the foregut ventrally into trachea (and lung buds) and dorsally into esophagus
Derivatives of midgut
Lower duodenum jejunum ileum cecum appendix ascending colon prox 2/3 or transverse colon
Terminal sac period
26 weeks - birth # of terminal sacs and degree of vascularization increase dramatically. more likely to survive during this stage with respiratory assistance.
Meckel’s diverticula
when the vitelline duct fails to obliterate. can lead to vitelline cysts for vitelline fistuals
Closure of foramen ovale causes…
the pressure to drop in the right atria because of decrease flow from placenta (pulmonary arteries) pressure to increase in left atria due to increase pulmonary venous return.
how long until gonads are indistinguishable?
until week 6
Pancreas
Formed by a ventral pancreatic bud in ventral mesentery and a dorsal pancreatic bud in dorsal mesentery Dorsal rotates left 90° to become retroperitoneal Ventral rotates left 270° to fuse with dorsal bud. Rotation fuses to form the main pancreatic duct
Folding of endocardial tubes
lateral folding brings heart tubes towards midline to fuse cranio folding bring heart tube just ventral to the foregut pocket
uroanal septum
forms the perineal body
plueroperitoneal membranes
located on the dorsal slide of the body wall that grow ventrally to close the pleuroperitoneal canal. This is the site where the myotomes attach.
mesonephros
temporary and functional During weeks 4-10 (functional 5-10) mesonephros appear from intermediate mesoderm as pronephro disappears. mesonephric ducts drain urie into developing bladder
Upper duodenum
arises form caudal most part of foregut that grows in the ventral mesentery. with rotation of gut tube, the duodenum and pancrease and pushed up against the body-wall and become secondarily retroperitoneal
Visceral peritoneum origin
from splanchnic lateral plate mesoderm that covers the gut tube
Stomach rotation
dilation of foregut that rotates: Left side moves ventrally and right side dorsally cranio caudal rotation tips the pylorus superiorly
What forms the diaphragm/
1) septum transversum (central tendon) 2) pleuroperitoneal membranes (muscles) 3) dorsal mesentery of the esophagus 4) Body wall mesoderm
Rectoanal canal forms…
rectum and upper anal canal
uteric bud forms
collecting tubes and cuts minor and major calyces ureters
Leydig cells
produce testosterone and support growth of mesonephric ducts and the development of male genital ducts and external genitalia.
smooth muscle wall in respiratory tract is dervied from
splanchnic mesoderm
Origin of parietal peritoneum
somatic lateral plate mesoderm on the inside of the body wall
Renal agensis
failure to form kidneys because either pronephros or mesonephros failed to form
what does the urogential system arise from?
intermediate mesoderm forms urogenital ridge
what forms the head, body and tail of pancreas?
dorsal pancreatic bud
What forms the upper arm of the umbilical herniation?
Small intestines
Intraperitoneal viscera
abd. esophagus spleen stomach liver and GB jejunum and ileum cecum appendix sigmoid
Male urogential sinus forms
bladder, prostate gland, bulbourethra gland, urethra
What forms external genetalia
proliferation of mesoderm and ectoderm around cloacal membrane
what forms labia majora
labioscrotal folds
Formation of vagina
caudal end of fused mullerian ducts come in contact with urogential sinus to form vagina. To make lining endodermal in origin.
ascent of the kidney
initially form near tail of embryo kidneys move upward and get subsequently higher blood supply.
dorsal mesentery of stomach becomes…
greater omentum
What forms the uncinate process of the pancreas?
ventral pancreatic bud
Derivatives of foregut
trachea and respiratory tract lungs esophagus stomach liver gallbladder and BD pancrease upper duodoenum
Development of Male reproductive tract
SRY releases TDF that causes gonad to develop into testis contatining spermatogonia, leydig cells and sertoli cells.
what does the urogential ridge form?
three nephric structures pronephros mesonephros metanephros gonads
umbilical hernia vs omphalocele vs gastroschisis
umbilical hernia is due to weakening around umbilicis during adulthood and is due to increase pressure in abdominal cavity omphalocele is the gut tubes no returning during physiological herniation and is rapped in amnion gastroschisis: birth defect where the guts still out of the belly due to a failure to close the body wall. not covered in amnion.
parietal peritoneum
formed by somatic mesoderm on body wall
Psuedoglandular period
6-16 weeks branched compound of endodermal line air tubes resembles glands. no alvioli and respiration is not possible
what forms labia minora?
urogenital folds
Sertoli cells
produce Mullerian inhibiting factor to cause the regression of paramesonephric ducts (mullerian ducts).
Trigone formation
mesonphric ducts get pulled downward as the bladder grows and incorporates into posterior bladder wall gives uteric bud own opening into bladder.
Rotation with physiological hernia
primary rotation 90° counter clockse rotation so lower loop moves towards left side of fetus at 10 weeks undergoes another rotation of 270° so that the jejunum enters first and ceum last.
skeletal muscle from diaphragm is derived from…
cervical somites
four lung periods
Psuedoglandular periof 6-16 weeks canalicular period (16-26 weeks) Terminal sac period (26-birth) Alveolar period (32 - 8 years)
Lower duodenum
arrises from cranial midgut becomes secondarily retroperitoneal
in males the shaft of the penis is formed by…
extension of the urogential sinus to from the corpora cavernosum and spongiosum Fusion forms the penile raphe
how do gonads arise
in intermediate mesoderm within the urogential ridge of embryo.
Pronephros
primitive and nonfunctional during 4th week C5-7 creates pronephric duct that extends and inducs the mesonephric duct formation
Primary retroperitoneal viscera
thoracic esphagus rectum anus
Hirshsprung disease
when neural crest cells do not form the parasympathetic ganglia to innervate the bowel wall and cant perform peristaltic movements
Hingut
uroanal septum divides the cloaca ventrally into the urogenital sinus and the rectoanal canal
Formation of uterus
fusion of paramesonephric ducts from caudal to cranial
Alveolar period
Week 32 - 8 years terminal sacs develop into alveolar ducts and alveolar sacs with new alveoli
metanephro
permanent and functional starts week5 becomes functional week 9-10 develop from outgrowth of mesonephric duct called a uteric bud and the metaneprhic blastema
what forms mons pubis
labioscrotal folds
