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					MIDGUT AND HINDGUT                              -
The pharynx extends from what to what?          buccopharyngeal membrane to lung bud
The foregut extends from what to what?          lung bud to hepatic diverticulum
The foregut is served by what artery?           celiac artery
The midgut extends from what to what?           hepatic diverticulum to junction of proximal 2/3
                                                and distal 1/3 of transverse colon
The midgut is served by what artery?            superior mesenteric artery
What are the derivatives of the caudal-most     liver, gall bladder, pancreas
foregut?
The hepatic diverticulum elarges within         transverse septum
what?
The bile duct is the remnant of what?           liver-foregut connection
What forms as an outgrowth off the hepatic      gall bladder and cystic duct
duct?
The pancreas arises from what two               ventral and dorsal pancreatic bud
primordia?
How do the pancreatic buds migrate?             ventral migrates around the gut to the right and
                                                dorsally to meet the dorsal pancreatic bud
What does each bud become in the mature         dorsal = body and tail, ventral = uncinate
pancreas?                                       process and head
What does the distal duct of the dorsal bud     distal main pancreatic duct
become?
What does the proximal duct of the dorsal       accessory pancreatic duct
bud become?
What does the duct of the ventral bud           proximal main pancreatic duct
become?
Which is larger - main or accessory duct?       main
What is an annular pancreas?                    ventral bud migrates around the gut both
                                                dorsally and ventrally resulting in a ring of
                                                pancreas surrounding and possibly constricting
                                                the duodenum
Who generally has an annular pancreas?          half the cases are infants
What are the adult signs and symptoms of an     nausea, bile-stained vomiting, excessive
annular pancreas?                               fulness after eating, gas, peptic ulcer
What is the incidence for annular pancreas?     1:7,000
The midgut corresponds with the caudal          corresponds with the caudal extent of the
extent of what nerve?                           parasympathetic innervation by the vagus
                                                nerve
The midgut forms a loop that is continuous      yolk stalk (vitelline duct)
with what?
What are the names of the two limbs that        cranial and caudal limbs
makeup the midgut loop?
The yolk stalk is in line with what artery?     superior mesenteric artery
Describe the direction of midgut loop           cranial limb rotates to the right and caudal limb
rotation.                                       rotates to the left
When does the midgut herniate into the          7th week
umbilical cord?
Which limb elongates?                           cranial limb
At week 7 how much has the midgut rotated       90 degrees around the axis of the superior
and around what axis?                           mesenteric artery
When does the midgut return to the body         during 10th week
coelem?
Describe the total rotatioin of the midgut at   rotates a final 180 degrees as is returns to the
week 10.                                        abdomen ---> total of 270 degrees
Where doest the cecum return to? Then           returns to the upper right quadrant of the
where does it migrate to?                       abdomen and then descends into the right iliac
                                                 fossa
What develops as the cecum descends?             vermiform appendix
What is an umbilical hernia and how big is it?   a bulge in the umbilicus, ranges in size from
                                                 that of a pea to a plum
What may cause the gut to enter an umbilical     intraabdominal pressure
hernia?
What is the incidence for umbilical hernias?     20% of all births
When do most umbilical hernias                   age 3
spontaneously close?
What is Meckel's (ileal) diverticulum?           retention of the vitelline stalk
What are the several forms of Meckel's           diverticulum, cyst, fistula (13.32)
diverticulum?
What is the incidence for Meckel's               2-4% of population (4 times more often in
diverticulum?                                    boys)
What is a sign that Meckel's diverticulum is     painless rectal bleeding
present in an infant?
What is a sign that Meckel's diverticulum is     intestinal obstruction
present in adults?
What is the rule of 2's?                         2 inches deep, 2 ft. from ileocecal junction, 2%
                                                 of population, 2x as likely in boys, may involve
                                                 2 or more different types of tissues in lining,
                                                 occurs around 2 years of age
The hindgut extends from where to where?         junction of proximal 2/3 and distal 1/3 of the
                                                 transverse colon to the junction of the upper
                                                 2/3 and lower 1/3 of the anorectal canal
                                                 marked by the pectinate line
The hindgut is served by what artery?            inferior mesenteric artery
What innervates the hindgut?                     parasympathetic innervation by the sacral
                                                 spinal cord
What marks the location of the embryonic         pectinate line (junction between different
anal membrane?                                   embryologic tissues)
What kind of tissue is above and below the       above = mesodermal origin, below =
pectinate line?                                  ectodermal origin
What is responsible for separating the cloaca    urorectal septum separates it into the rectum
and what is it separated into?                   and primitive urogenital septum
Is the urorectal septum endodermal,              mesodermal
mesodermal, or ectodermal?
The urorectal septum divides the cloacal         urogenital membrane, anal membrane
membrane into what 2 membranes?
The primitive urogential sinus subdivides to     urinary bladder, pelvic urethra, definitive
form what structures?                            urogenital sinus
What is another name for Hirschsprung's          aganglionic megacolon
disease?
What are the effects of aganglionic              a delay in passage of meconium and chronic
megacolon?                                       constipation
When is hirschsprung's disease normally          within the 1st year of life
diagnosed?
What is the cause of Hirschsprung's?             due to a failure of migration of neural crest
What is the incidence of Hirschsprung's?         1:10,000
What neural crest-derived tissue lines the gut   the enteric plexus
and causes peristalsis?
Which portion of the colon is normal in          the megacolon
Hirschsprung's?
Why can't fecal matter pass through the          the fecal matter builds up until it reaches a
colon in Hirschsprung's?                         portion that lacks the enteric plexus, this
                                                 portion doesn't relax thus fecal matter can't
                                                  pass through
Fecal matter stored in the bowel until birth is   meconium
called what?
Describe meconium's appearance.                   thick, sticky, tar-like stool
Meconium consists of what?                        digested remains of swallowed amniotic fluid,
                                                  hair, skin cells
Passage of meconium prior to birth can            aspiration of the meconium
result in what?
The failure to pass meconium may suggest          aganglionic megacolon or imperforate anus
what?
Meconium appearing at the opening of the          rectovaginal fistula or urorectal fistula
vagina or urethra indicates what?
In the case of an imperforate anus or             the pectinate line
urorectal fistula the anal membrane may be
intact at the level of what?
In the case of an imperforate anus or             the anal membrane
urorectal fistula the rectum may terminate at
some level above what?
A urorectal fistula may form between the          vagina, bladder, urethra
rectum and what other structures?
What is the incidence of imperforate anus or      1:7,000
urorectal fistulas?
URINARY SYSTEM                                    -
The urinary and genital systems share many        both arise from the intermediate mesoderm of
of the same embryonic tissues. Give 2             the dorsal body wall, both appropriate ducts
examples.                                         from primordial ducts which ener into the
                                                  cloaca
The urinary system originates as how many         3
separate sets of kidneys?
These 3 kidneys come from what tissue?            intermediate mesoderm
What are the names of the 3 kidneys?              pronephros, mesonephros, metanephros
Where is pronephros found?                        cervical region
How long is pronephros around?                    it is transient and regresses early
Where is mesonephros found?                       throughout the thoracic and upper abdominal
                                                  regions
How long is mesonephros around?                   its a relatively large organ during the early
                                                  second month, but has all but disappeared by
                                                  the end of the 8th week
Where is metanephros found?                       pelvic region
How long is metanephros around?                   from the 5th week throughout life
The early kidneys as well as the gonads           urogenital ridge
develop as what structure that protrudes
downward into the body coelom?
What is retained in part from the                 ducts and tubules
mesonephros?
nephrotome = ?                                    a single segment of the pronephric kidney
Adjacent nephrotomes of the pronephric            pronephric duct
kidney merge to form what?
What is the caudal extension of the               the mesonephric duct (14.2)
pronephric duct?
Where does the mesonephric duct                   in the cloaca
terminate?
When does the mesonephric kidney appear?          in the 4th week
What does a renal corpuscle of the                vascular glomerulus, Bowman's capsule
mesonephros form?
What part of the mesonephros forms the            a renal corpuscle
vascular glomerulus and Bowman's capsule?
What extends from Bownman's capsule to           mesonephric excretory tubules (14.3A)
the mesonephric duct?
Where and when does the ureteric bud             appears as an outgrowth of the mesonephric
appear?                                          duct about day 28
What is another name for the ureteric bud?       metanephric bud
Where does the ureteric bud ascend to and        ascends to the urogenital ridge and induces
what does it do?                                 the formation of the metanephric kidney
What does the ureteric bud become?               the collecting system of the metanephric
                                                 kidney: ureter, renal pelvis, collecting tubules
From what does the excretory system              metanephric blastemal cap
develop?
Collecting tubules induce the formation of       cell clusters
what within the blastemal cap?
Cell clusters give rise to what?                 renal vesicles
Renal vesicles form what?                        renal tubules
Renal tubules make contact with what?            collecting tubules
Renal vesicles induce what else in the           appropriate branching of the ureteric bud
ureteric bud?
The renal tubule elongates to become what?       proximal and distal convoluted tubules, loop of
                                                 Henle
What forms a Bowman's capsule?                   the proximal convoluted tubule
When do the kidney's become functional?          10th week
What is the most common primary tumor of         Wilms' tumor
childhood?
What is the incidence of Wilms' tumor?           1:12,000
Describe the indications of Wilms' tumor.        asymptomatic palpable abdominal mass
Where is the gene for Wilms' tumor               expressed in the fetal kidney (WT1 on
expressed?                                       chromosome 11)
What causes the tumor - activation or            inactivation
inactivation of the gene?
What is WAGR syndrome?                           W- Wilms' tumor, A- aniridia, G- genitourinary
                                                 anomalies, R- retardation
What is aniridia?                                absence of the iris of the eye - usually partial
Describe the frequency of the different          A - present in all cases, G - variable, R -
symptoms of WAGR syndrome.                       variable
What causes WAGR?                                most are due to deletion of a section of the
                                                 short arm of chromosome 11
What accounts for the variability in WAGR?       the amount of material deleted in chromosome
                                                 11
What is the genetic characteristics of the       adult - autosomal dominant, infantile -
adult and infantile form of polycystic kidney?   autosomal recessive
What are the symptoms of adult polyscystic       blood in urine, recurrent bladder infections,
kidney?                                          high blood pressure
Incidence of polycystic kidney in adults?        1:500
Incidence of polycystic kidney in infants?       1:5,000
Describe mortality of polycystic kidney in       significant mortality in 1st year
infants.
One third of survivors of infantile polycystic   dialysis or transplantation by age 10
kidney will need what?
Why do the metanephric kidneys ascend?           due to differential body growth
What ascends with the kidneys?                   arterial supply (multiple renal arteries is a
                                                 common finding)
Describe the orientation of the hilum as the     it rotates to face medially
kidney ascends.
What percent of all newborns have an             10%
abnormality of the urinary tract?
A pelvic kidney is usually located where?      a single kidney may stop its ascent at the level
                                               of the common iliac and umbilical arteries
When might a pelvic kidney cause problems      during pregnancy it may interfere with
in adult life?                                 expansion of the uterus
Incidence of pelvic kidney?                    1:1,000
What is renal agenesis due to?                 failure of the ureteric bud to contact the
                                               metanephric intermediate mesoderm
What are the two types of renal agenesis?      unilateral and bilater renal agenesis
What is the incidence of both types of renal   unilateral - 1:1,000, bilateral - 1:3,000
agenesis?
Unilateral renal agenesis is usually           single umbilical artery
accompanied by the presence of what?
Which form of renal agenesis is fatal?         bilateral
Bilateral renal agenesis is associated with    oligohydramnios (too little amniotic fluid)
what and why?                                  because the kidneys are an important source
                                               of amniotic fluid
What are the characteristics of Potter         bilateral renal agenesis, oligohydramnios,
syndrome?                                      hypoplastic lungs, flattened face, wrinkled skin,
                                               others...
What is horseshoe kidney?                      two kidneys that fuse at their medial borders
Where does horseshoe kidney ascend to?         they fail to ascend pst the inferior mesenteric
                                               artery
What are common problems from horseshoe        its at a level where it receives minimal
kidney?                                        protection, hyperextension of the spine may
                                               cause discomfort
Incidence of horseshoe kidney?                 1:600 (1/3 remain asymptomatic)
What is an ectopic ureter?                     a ureter that opens anywhere except into the
                                               bladder
What other ureter anomaly is common?           duplications of the ureter and renal pelvis
Where do ectopic ureters open in boys? in      boys - prostatic urethra, girls - urethra or
girls?                                         vagina
How does the urogenital sinus form?            it forms as the urorectal septum divides the
                                               caudal hindgut
the primitive urogenital sinus is continuous   the allantois which extends into the umbilical
with what superiorly?                          cord
The allantois becomes what?                    the fibrous urachus and later the median
                                               umbilical ligament
The primitive urogenital sinus becomes         urinary bladder, pelvic urethra, definitive
what?                                          urogenital sinus
The ureteric bud forms from what?              an outgrowth off the mesonephric duct
What kind of tissue makes up the ureteric      both are mesoderm
bud? mesonephric duct?
The mesonephric duct originally empties into   urogenital sinus
what?
What lines the urogenital sinus?               endoderm
The bladder enlarges and draws the             the ducts dorsal wall (14.14)
mesonephric duct where?
The ureter forms from what?                    ureteric bud
The mesonephric duct drawn into the            trigone of the bladder, it's eventually
urogenital sinus becomes what? What            overgrown by endoderm
happens to it eventually?
What is another name for the allantois?        allantoic diverticulum
What does the allantois connect with?          it extends into the umbilical cord and connects
                                               internally with the apex of the bladder
What becomes of the allantois?                 it normally becomes firotic and is called the
                                                 urachus, it is then retained as the median
                                                 umbilical ligament
The remnanats of the allantois may be            urachal fistula, urachal cyst, urachal sinus
retained as what?
What is the incidence of these urachal           1:40,000
malformities?
What is the cause of exstrophy of the            due to failure of the mesodermal ventral body
bladder?                                         wall to close
Incidence of exstrophy of the bladder?           1:40,000
GENITAL SYSTEM                                   -
What is the urogenital ridge composed of?        urinary ridge which lies laterally, gonadal ridge
                                                 which lies medially
Which ducts serve the urogential ridge?          mesonephric duct (of Wolff), paramesonephric
                                                 duct (of Mueller) (14.19)
Where does the mesonephric duct                  in the cloaca
terminate?
Where do primordial germ cells arise from?       yolk sac
Where do primordial germ cells migrate to?       gonad where they are welcomed by epithelial
                                                 cells
What forms primitive sex cords?                  epithelial cells filing inward in columns
What determines maleness or femaleness?          SRY - sex-determining region of the Y
                                                 chromosome
What develops and doesn't develop in the         medullary cords develop, no cortical cords
testis?                                          develop, thick tunica albuginea develop
What develops and doesn't develop in the         medullary cords degenerate, cortical cords
ovary?                                           develop, no tunica albuginea develops
What duct is important in the male?              mesonephric duct (Wolffian duct)
What duct is important in the female?            paramesonephric duct (Mullerian duct)
In the testis the primitive sex cords become     medullary cords
what?
The medullary cords form what deep in the        rete testis (14.20)
testis?
What do the rete testes merge with?              mesonephric tubules (efferent ductules)
Mesonephric tubules are continuous with          mesonephric duct (vas deferens)
what?
What happens to the paramesonepric duct in       it's actively inhibited by MIS - Mullerian
males?                                           inhibiting substance
In the ovaries what do the primitive sex cords   the medullary cords and degenerate
become?
How do cortical cords form and what              a second set of sex cords (cortical cords)
becomes of them?                                 invade and become the follicle cells
What happens to the mesonephric tubules          they disappear
and the mesonephric duct?
What happens to the paramesonephric duct?        it becomes the uterine tubes, uterus, and
                                                 upper vagina
Describe the migration of the left and right     they merge in the midline and contact the
paramesonephric ducts.                           primitive urogential sinus
What forms at the point of contact of the left   the endoderm proliferates to form the
and right paramesonephric ducts and by           sinovaginal bulbs
what tissue?
The sinovaginal bulbs expand upward and          the vaginal plate
fuse to form what?
Describe the origins of the different parts of   upper 1/3 - Mullerian duct (mesoderm), lower
the vagina.                                      2/3 - endoderm
When is the entire vagina canalized?             by the 5th month
What is a possible remnant of the male           Gartner's cyst
system?
SY induces expression of what?                     MIS and testosterone
Describe the conversion of testosterone.           converted by 5 alpha-reductase to
                                                   dihydrotestosterone
What does testosterone direct?                     mesonephric ducts int he masculine direction
What does dihyrotestosterone direct?               external genitalia in the masculine direction
The actions of testosterone and                    the sensitivity of receptor sites on cells in the
dihydrotestosterone are dependent upon             target tissues
what?
What are the target tissues?                       internal mesonephric genital ducts, external
                                                   genitalia, others: skin, muscle, bone, nervous
                                                   system
What does AIS stand for?                           androgen insensitivity syndrome
Describe the genetic makeup of an AIS              a genetic male - 46, XY
individual.
What produces androgens?                           the testes
Why are all tissues insensitve to androgens        due to a mutation on chromosome 11
in AIS?
Does the individual develop as a male or           the individual develops in the female direction
female in AIS?
What female characteristics do an AIS              the Mullerian ducts are inhibited so the
individual lack and why?                           individual lacks uterine ducts, uterus, and the
                                                   upper 1/3 of the vagina
Describe the individual's phenotypically           tall, exhibit female behavioral preferences,
female appearance.                                 axiallary and pubic hair scanty, testes do not
                                                   descend, amenorrheic, do not develop acne
Incidence of AIS?                                  1:20,000 live born males
From what tissue does the vagina form?             mesoderm and endoderm
Sinovaginal bulbs migrate in which direction?      downward
True or false. The vagina and urethra open         TRUE
separately into the definitive urogenital sinus.
What tissue forms on either side of the            cloacal folds
cloaca?
Cranially, what do the cloacal folds merge to      the genital tubercle
form?
When the perineum forms, the cloacal folds         anal folds, urethral folds
subdivide into what?
What appears lateral to the urethral folds?        genital swellings
In the female what do the genital swellings        labia majora, labia minora, clitoris
become? urethral folds? genital tubercle?
In the male what do the genital swellings          scrotum, body of the penis, glans of the penis
become? urethral folds? genital tubercle?
The urethral folds cover what to become            they cover the urethral groove to form the
what?                                              penile urethra
The ectodermal cells migrate inward and            glandular urethra
canalize to form what?
What is hypospadias?                               incomplete closure of the urethral folds leaving
                                                   openings along the raphe
What is a downward curve of the penis              chordee
(especially when erect) and what abnormality
does it often accompany?
Incidence of hypspadias?                           1:350 male births
Where does the testis/ovary develop?               retroperitoneally in the upper posterior
                                                   abdominal wall
Where are the testes at month 7?                   they have descended to a location just above
                                                   the pubic bone
What is the vaginal process?                       a diverticulum of the peritoneal cavity present
                                                   in both sexes (14.40)
Where does the vaginal process extend to?          downward into the future scrotum/labia majora
What forms the inguinal canal?                     the tunica vaginalis surrounding the vaginal
                                                   process along with attending peritoneal tissues
Where do the the testes migrate to at birth?       they descend through the inguinal canal
The tunica vaginalis reflects over the testis to   visceral and parietal
form what two layers?
What happens to the neck of the vaginal            it obliterates
process?
What is the genetic description of Turner          45, XO
syndrome?
How many turner syndrome individuals               1%
survive to birth?
Incidence of Turner syndrome?                      1:3,000 live female births
Describe the phenotype of Turner syndrome.         phenotypic female: streak gonads, short
                                                   stature, broad and shield-like chest, high
                                                   arched palate, possible coarctation of the aorta
Turner syndrome is the most common cause           primary amenorrhea
of what?
Genetically describe Klinefelter syndrome.         47, XXY
Describe the phenotypic characteristics of         phenotypic male: elongated body (arms longer
Klinefelter syndrome.                              than legs), small firm testes (hypogonadism),
                                                   lack of body and facial hair, excessive breast
                                                   development, most are infertile, some difficulty
                                                   with language, reading and writing
Incidence of Klinefelter syndrome?                 1:500-850 live male births

				
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