embryology Flashcards
site of produciton fo sonic hedgehog
base of limbs in zole of ploarizing activity
what is role of sonic hedgehog
patterning along ANTERIOR POSTERIOR AXIS
what happens if sonic hedgehog mutation
CNS development anterior posterior
holoprosencephaly
where is wnt-7 produced
apical ectodermal ridge at the distal end of each limb = thickened ectodermal ridge
what does wnt-7 do?
necessary for proper organization along dorsal-ventral axis
where is fgf made?
at apical ecotdermal ridge
what does fgf do?
stimulates mitosis of underlying mesodrem
lentening of limbs
what are homeobox genes
involved in segmental organization fo embryo in a craniocaudal direction
what do hox genes code for
transcription factors
what happens if hox genes are mutated
appendages in wrong locations
name the gene involved in anterior posterior axis
sonic hedgehog
name the gene invovled in ventral dorsal organization
wnt7
name the gene involved in lengethening of limbs
FGF
name the gene involved in craniocaudal direction
homeobox genes
describe what is happenign on day 0 of early fetal development
fertilization by sperm, formign zygote and initaiting embroygensis
what happens in the first week of early fetal development
hCG production begins aroudn the time of implantatino of the blastcyst
when does the blastocyst implant
day 6
what happens in the second week fo early fetal development
bilaminar disc - epiblast and hypoblast
two weeks, two layers
what happens in the third week of early fetal development
trimaniar disc
gastrulation
primitive streak, notochord, mesoderm and its organiation and neural plate begins to form
when is the embryonic period?
3rd to 8th week of gestation
when does the neural tube form and close
tis formed by neuroectoderm beginning at third week and closes by week 4
what goes on in the embryonic period
neural tube formes from neuroectoderm and clsoes by week 4
organogensis
EXTREMELY SUSCEPTIBLE TO TERATOGENS
when does the heart first start to beat
week 4
whne do upper and lower limb buds begin to form
week 4
4 weeks = 4 limbs
when is the heart beat first able to be heard via transvaginal ulstrasound
week 6
what happens in week 6
fetal cardiac activity visible by transaginal ultrasound
when deos the genitalia have male and female characteristics?
week 10
what happens in week 10
genitalia have male and female characteristics
define gastrulation
proces that forms the trilaminar embryonic dist
when does gastrulation happen
week three
what is the result of gastrulation
estabilshed the ectoderm, mesoderm and endoderm gem layers
how does gastrulatio begin
starts wtih teh epiblast invaginationg to form the primitve streak
what is forming at the same time in gastrulation
primitive streak
notochord
mesoderm and its organization
neural plate beigns to form
define: agenesis
absent organ due to absent primordial tissue
define: aplasia
absent organ despite presence of primordial tissue
hypoplasia
incomplete organ development, primordial tissue present
define: deformation
extrinsic disruption; occurs after embryonic period (308 weeks)
define: disruption
secondary breakdown of previously normal tissue or struture
what type of error in organ morphogenesis is amniotic band syndrome
disruption - secondary breakdown or previously normal tissue or struture
define: malformation
intrinsic disruption
occurs during embryonic period 3-8th week
what is a sequecne
abnormalities result form a signel primary mbryologic event
when is the developing baby most susceptible to teratogens
in the embryonic period
organogenesis
3rd to 8th week
describe effect of teratogens before the embryonic period
all or none effect
describe effect of teratogens after week 8
growth and function affected
what is the leading cause of intellectual disability in the USA
fetal alcohol syndrome
what is the most common cause of low birth weight in developed countries
smoking
effects of alcohol on fetus
increased incidence of congeintal abnormalities
pre and postnalta developmental retardation
microcephaly
facial abnormalities - smooth philtrum, hypertelorism, limb disolcation, heart defects
heart lung fistulas
holoprosencephay
what is the mechanism behind congenital abnormalities in fetal alcohol syndrome
failed migration
describe facial anomalies in fetal alcohol syndrome
smooth philtrum
hypertelorsim - organs are too far apart
what are the most severe abnormalities in fetal alcohol syndrome
holoprosencephaly and heart lung fistulas
what are the toher defects in fetal alcohol syndrome besides facial abonrmaolities
heart defects
limb dislocation
intellectural disabiltiy
microcephaly
what is the teratogen smooth philtrum heart lung fistula hypertelorism intellectula disability microcephaly heart defects limb disolcation
alcohol!
most common cause of low birth weight in deeloped coutnries
smoking in rpegnancy
most common casue of intellectual disability in developed countries
alcohol
whats the difference between dizygotic twins and monozygotic twins
dizygotic twins - from two egges separtely fertilzed by two different sperm - alwasy two zygotes with two separate amnion and two separtae placenta
monozygotic - from 1 fertilized egg and 1 sperm that splits into 2 zygotes before day 13.
what determines the number of chorins/placenta and amnion/fetal membranes in monozygotic twins
the timing of the separtion fo the 1 fertilzied egg
describe type of monozygotic twins that cocurs if division occurs between teh 2 cell stage and the morula
dichorionic
diamniotic
monozygotic twins
describe type of monozygotic twins that occurs if division occurs between the morula and the blastocyst
monochorionic
diamniotic
monozygotic twins
one placenta and two sets of membranes
describe type of monozygotic twins that occurs if cleavage occurs bweetn the blastocyst and formed embryonic disc stage
monochorionic monoamniotic monozygotic twins one placenta one set of membranes
what happens i fcleavate happens greater than 13 days after the formed embroyonic dis c has formed
monozygotic twins
monochorionic
monoaminotic
conjoined
twins if celavge between days 0 and 4
dichorionic diamniotic with fused or separate palcentas
twins if cleavage between days 4 and 8
monochorionic diamniotic monozygotes
morula - blastocyst
twins if cleavage between 8 and 12 days
monochorionic monoamniotic monozygotes
blastocyst - formed embryonic dise
twins if cleavage at > 13 days
monochorionic monoamniotic conjoined monozygotic twins
what is the most common type of monozygotic twin
monochorionic diamniotic monozygotic twins
days 4-8
morula and blastocyst
what is second most common type of monozygotic twin
dichorionic diamniotic monozygotic twins fused or seprate palcenta
days 0-4
two day cell to morula
what is the placenta
first site of nutrient and gas exchange between mother and fetus
what is the fetal component of the placenta
cytotrophoblast
syncytiotrophoblast
what is the cytotrophoblast
inner layer of chorionic villi near featl vessels
makes cells
what is the syncyciotrophblast
outer layer of chorionic villi near maternal blood
makes hCG
what is the maternal component of the placenta
decidua basalis
what is the decidua basalis dericed from
endometrium
where is maternal blodo int eh palcenta
between the decidua basalis and the syncyctiotrophoblasts
describe what youd see in the cross section of the umbilical cord
two umbilical arteirs - bringin blodo back from the fetus to the placenta
one umbilical vein - takign blood fromplacenta to the lier and then IVC of to teh IVC via the ductus venosus and the allantoic duct amonsgt wharton jelly
what causes a 2 vessel cord
congenital and chromosomal anomalies - single umbilical artery
what does the umbilical artery do
returns deozygenated blodo from fetal internal iliac arteries to palcenta
what doe the umbilical vein do
supplies oxygenated blodo from placenta to dutus
drains into IVC via liver or via ductus venosus
what is the urachus
@ 3rd week - yolk sac froms the allontois - extends into the urogenital sinus
allantois becomes the urachus - a duct between fetal bladder and yolk sac
what is a patent urachus
total failure of the urachus to obliterate - urine fischarge form umbilicus
what is a urachal cyst
partial failure of urachus to obliterate - fluid filled vaivity lines with uroepithelium btween the umbilicus and bladder
consequences of urachal cysts
infection
adenocarcinoma
what is a vesicourachal diverticulum
slight failure of urachus to obliterate causes outpouchign of bladder
what is a urachus
the allontosi at third week connected the yold sac to the urogenital sinus – becomes a urachs that acts as a duct between teh fetal bladder and yolk sac
what is the vitelline duct
at the 7th week obliteration fo the vitelline dut/omphalo-mesenteric duct that connects the yok sac to the midgut lumen
what is a vitelline fistula
vitelline duct fails to close - meconium distchange fromumbilicus
what is a meckel diverticulm
partial closure of vitelline duct with patent portion attacted to ileum
a true diverticulum
melena
hematochezia
abdominal pain
partial closeure of vitelline duct with patent portion attahed to ituem
true diverticulum
meckeldiverticulum
what type of tissue can be present in meckel diverticlum
pancreatic/gastric
urine from the umbilicus = ?
patent urachus
meconiium from teh umbilicus = ?
vitelline fistula
what is the pathogeneis sof cleft lip?
failure of the fusion of the maxillary and medial nasal processes - formation fo primary palate
what results if maxillary adn medial nasal processes fail to fuse
no primary palate
cleft lip
what is the pathogenesis of cleft palate
failure of fusion of the two lateral palatine processes
OR
failure of fusion of lateral palatine processes with the nasal septum and or medial palatine processes
= formation of the secondary palate
what happens if the two lateral palatine processes fail to fuse
cleft palate
what happens if the lateral palatine process fails to fuse with the nasal septum
cleft palate
what happens in teh lateral palatine process fails to fuse with the medial palatine process
cleft palate
describe the anatomic deltas in hypospadias
abnormal openign on the ventral side
what causes hypospadias
failure of the urethral folds to fuse
what is associated with hypospadias
inguinal hernia and cyrptorchidism
name the defect associated with inguinal herina and cryptochidism
hypospadias
which is mroe common, hypospadias or epispadias
hypospadiaes
describe the anatomic deltas in epispadiasis
abnormal opening of the dorsal surface of penis
what causes epispadiasis
faulty positioning of the genital tubercle
what other findings are associated with epispadias
bladder exstrophy
what else is associated with bladder exstrophy
epispadiasis
failure of the urethral folds to fuse
hypospadias
faulty positiong of hte genital tubercle
epispadias
whats the role of the gubernaculum
tis a band of fibrous tissue that ancors the testes wtihin the scrotum
what does the gubernaculum become in feamles
the round ligament and the ovarian ligament
round ligament is from fundus to labia majora
ovarian ligament is from fundus to ovary
when do you suspect urethral injury
if see blood at the urethral meatus
what type of damage do you suspect if person has a pelvic fracture or blunt force
posterior urethra - membranous portion
urine into the retropubic space
what type of famage do you suspect in a perineal straddle injuery
anterior urethra - penile urethra at risk of damage
cause urin to leak beneath deep fascia of buck
what happen sif buck fascia is torn
urine can leak into superficial perineal space
what is injured if you see urine in the retropubic spave
membranous portion of urethra
what is injured if urine is contained in bucks fascia
penile portion of the urethra
what is injuered if you see urine in the superfiical perineal space
bucks fascia has ruptured and penile urethra inuered
what are teh efects of NO on the male sexual response
No - icnrease cGMP - smooth muscle relaxation - vasodilation - proecertile
what are the effects of NE on the male sexual response
NE - increases intracellular calcium – smooth muscle contraction – vasoconstriction – antierectile
what causes a) Erection b) emission and c) ejaculation in male sexual response
a) parasympathetic in the pelvic nerve
b) sympahtetic in the hypogastic nerve
c) visceral and somating in the pudendal nerve
how do PDE-5 inhibitors work
inhibit cGMP breakdown.
sildenafil
what wont happen if pelvic nerve ruined
no erection - parasympathetmc
what wont happen if hypogastric nerve damaged
no emission - sympahtetic
what wont happen if pudendal nerve damaged
no ejactulation - visceral and somatic
describe the stages of the female sexual response
excitement - plateau - orgasm - resolution
what happens in female sexual response of excitement
excitement - uterus elevates
vaginal lubrication
what happens in female sexual response of platuea
expansion of inner vagina
what happens in female sexual response of orgasn
uterine contractions
what mediates the female sexual response
autonomic nervous system
what accompanies the female sexual response
tachycardia and skin flushing
what phase of female sexual response: uterus elevates and vaginal lubs
excitement
what phase of female sexual response: uterine contractions
orgasm
what phase of female sexual response: expansion fo inner vagina
platuea
what is the pathway of sperm during ejaculation
SEVEN UP
seminiferous tubules - epididymis - vas deferens - ejaculatory ducts - urethra - penis
