Histology - Fetal Development and Complications - Reverse Flashcards
Measures of body length (CRL, lemur length) increase faster than measures of width increase (biparietal diameter, abdominal circumference).
Fetal Proportional Growth
3200 g (7 lbs)
Normal Birth Weight
< 2500 g (5.5 lbs)
Low Birth Weight
< 500 g (1.1 lbs)
Fatal Birth Weight
< 10th percentile in weight for gestational age, but weight for size is normal
Small for gestational age (SGA)
< 10th percentile in weight for gestational age and < 2.5th percentile for abdominal circumference. Mortality is 30 times more likely, mental development may be affected.
in utero growth retardation (IUGR)
Preterm birth
test for preterm delivery risk: vaginal swab for placental adhesive glycoproteins
Fetal fibronectin (fFN) test
Respiratory distress due to underdeveloped lungs
Respiratory distress syndrome (RDS)
glucocorticoids to promote surfactant secretion in the lung to prevent collapse.
Respiratory distress syndrome (RDS) prenatal treatment
continuous positive airway pressure (CPAP) to maintain airway patency.
Respiratory distress syndrome (RDS) POST-natal treatment
test for RDS risk. Lecithin should rise relative to sphingomyelin beginning in the 34th week, 2:1 = low RDS risk. Amniotic fluid sampled by amniocentesis or vaginal swab.
Lecithin-sphingomyelin ratio
sampling amniotic fluid w/ needle guided by ultrasonography. 14-20 weeks for adequate fluid. Fetal calls for karyotyping, fetal metabolites, proteins, hormones, etc.
Amniocentesis
biopsy of chorionic villus w/ needle guided by ultrasonography. 10-14 weeks (after 14 wks, amniocentesis preferred). Slightly higher risk (1-2%), less accurate, earlier karyotyping.
Chorionic villus sampling (CVS)
identifying fetal markers in maternal blood. Looking for a-fetoprotein and hCG levels. False positives numerous.
Maternal serum screening
fetal marker in maternal blood that can show neural tube defects, GI defects, Down syndrome
a-fetoprotein
fetal marker in maternal blood used to test for molar pregnancy, ectopic pregnancy, choriocarcinoma, down syndrome.
hCG
Encoscopic procedure to visualize the fetus. Invasive, high risk (5-10%), used only in extreme casus
Fetoscopy (fetendo)
sampling of umbilical vein blood for genetic or metabolic disoreders (also called cordocentesis). > 17 weeks (cord large enough), same risk as CVS (1-2%)
Percutaneous Umbilical Cord Blood Sampling (PUBS)
extraction of fluid from the peritoneal cavity within the abdomen. Invasive: must penetrate vagina and peritoneum. Looking for blood; indivative of tubal rupture during ectopic pregnancy.
Culdocentesis
dilation of the cervix and removal of endometrium (scraping or suction). Screens for polyps, cancer, ectopic pregnancy. Placental tissue floats in saline, cancer doesn’t. comparison with hCG levels usually necessary.
Dilation and curettage (D and C)
waxy or cheese-like white substance found coating the skin of newborn human babies. Starts developing on the baby in the womb around 18 weeks into pregnancy.
Vernix caseosa
very fine, soft, and usually unpigmented, downy hair as can be found on the body of a fetusor newborn baby. It is the first hair to be produced by the fetal hair follicles, and it usually appears on the fetus at about 5 months of gestation.
Lanugo
Formed by fusion of amnion and chrion. Ruptures prior to birth, ‘water breaking’.
Amniochorionic membrane (ACM)
Premature rupturing of the ACM. Bands/cords of ACM constrict fetal body parts, may affect development of more distal structures.
Amniotic Band Sundrome (ABS)
500-1000 ml of circulating clear, watery liquid that contains fetal cells, proteins, electrolytes that can be collected via aminocentesis.
Amniotic fluid
amniotic cells lining cavity, fiddusion of maternal tissue fluid, fetal urination.
Sources of Amniotic fluid
Enters fetal circulation by being swallowed into GI tract, aspiated into lungs, and absorbed through skin. Returns to maternal circulation through uteroplacental circulation, excretion into amniotic cavity and diffusion into maternal tissue.
Amniotic fluid circulation
Cushions, prevents adhesion, permits movement, permits growth, barrier to infections, regulated body temperature, regulates fluid/electrolyte homeostasis.
Amniotic fluid functions
too much amniotic fluid; >1500 ml. Assoc. w/ severe malformations that prevent swallowing of amniotic fluid.
Polyhdramnios
Too little amniotic fluid; < 400 ml. Assoc. w/ renal agenesis, urinary blockages, premature rupture of ACM (PROM). May lead to slowed growth or oligohydramins sequence.
Oligohydramnios
Abnormal appearance due to compression of fetus against uterus, e.g., limb abnormalities, flattened face. Typically caused by bilateral renal agenesis or ACM rupture. Characterized by oligohydramnios, anuria (no urination), pulmonary hypoplasia (under-developed lungs)
Oligohydramnios (Potter’s) Sequence
Attaches fetus to placenta. (55 cm length, 1-2 cm diameter) Contains: 1 umbilical vein (blood: placenta to fetus), 2 umbilical arteries, (blood: fetus to placenta), loops of intestine, yolk sac, vitelline vessels, allantois (waste collection).
Umbilical cord
risk of cord prolapse or the cord encircling fetal neck, called nuchal cord.
long cord
restricted fetal movements, early detachment of placenta from uterus during delivery.
short cord
fetal hypoxia/anoxia (little/no oxygen); may be fatal
True knot (umbilical)
Collection, storage of fetal blood cells. Alternative to bone marrow transplants. Pros: No discomfort, abundant viabble stem cells, minimized host-graft rejection. Cons: expensive, low prob of use.
Umbilical cord blood banking
site of nutrient and gas exchange between fetus & mother; produces pregnancy hormones like hCG.
Placenta
maternal part of the placenta, derived from endometrium
Decidua basalis
fetal part of placenta, derived from chorion
Villous chorion
endometrium during pregnancy adjacent to the smooth chorion
decidua capsularis
endometrium during pregnancy not directly associated with the chorion.
decidua parietalis
name for extraembryonic mesoderm plus trophoblast layers
Chorion
fetal placenta adjacent to decidua basalis, highly vascular. develops as the cytotrophoblast and extraembryonic mesoderm and grows into the syncytiotrophoblast. NO MIXING OF MATERNAL AND FETAL BLOOD!!
Villous chorion
less vascular, non-placental region adjacent to decidua capsularis
Smooth chorion
- synctiotrophoblast 2. cytotrophoblast 3. extraembryonic mesoderm 4. endothelial cells lining fetal capillaries.
Placental barrier before 4 months fertilization age
- syncytiotrophoblast 2. endothelial cells lining fetal capillaries. Now increased exchange. Cytotrophoblast cells detach and migrate to lin maternal arteries.
Placental barrier after 4 months fertilization age
blocks: large, complex molecules, many protein hormones, many bacteria. Allows: gas, nutrient, waste exchange, steroid hormones, some antibodies, most medications/drugs, many viruses.
Placental barrier (membrane)
clinical concern > 4 months. Caused by failed migration of cytotrophoblast cells or maternal immune response to invading cytotrophoblast cells. Increases pressure in maternal vessels. Results in maternal hypertension, preoteinuria, slowed fetal growth, potential death.
Preeclampsia
follows preeclampsia and is characterized by seizures.
Eclampsia
placenta attaches to the myometrium of uterus
Placenta accreta
placenta invades myometrium of uterus
Placenta increta
placenta penetrate the uterus and extends into body cavity
Placenta percreta
dichorionic, diamniotic (DCDA, DiDi): 2 amnions, 2 chorions, 2 placentas. 2 oocytes released at ovulation & fertilized separately, unique DNA, ‘fraternal’.
DZ twins
2 amnions, 1 chorion, 1 placenta. 1 oocyte released at ovulation, fertilized by 1 sperm, same DNA, ‘identical’. each blastocyst implants separately in endometrium
MZ twins: dichorionic, diamniotic (DCDA, DiDi)
1 amnion, 1 chorion, 1 placenta. 1 oocyte released at ovulation, fertilized by 1 sperm. I embryblast at implantation = 1 amnion. 2 epiblasts after implantation = 2 fetuses. 1 trophoblast = 1 chorion, 1 placenta.
MZ twins: monochorionic, monoamniotic (MCMA, MoMo)
Spermreach oocyte, pass through CR. Acrosome reaction (male), Zona reaction (female). Sperm fuses with ocyte membrane, oocyte completes M2. Pronuclei fuse to from single diploid nucleus.
Day 1
Cleavage, compaction (day 4), cavitation, hatching, implantation (day 6)
Week 1
uteroplacental circulation, trophoblast differentiation (cytotrophoblast and syncytiotrophoblast.), bilaminar disc formation, chorionic cavity formation, hcG detectable day 8.
Week 2
ectopic pregnancy, placenta previa, molar pregnancy, choriocarcinoma.
Week 2 complications
Gastrulation, neurulation, NODAL expression, FGF8 expression, hypoblast displaced, body axes established, lateral body folding.
Weeks 3-4
forms urogenital system
Intermediate mesoderm
forms connective tissue of body wall and limbs
parietal layer of lateral plate mesoderm
GI/respiratory organs exxcept epithelial lining
visceral layer of lateral plate mesoderm
somites differentiate (wk 4), myotome differentiation (wk 5), resegmentation (wk 5), organogenesis
Weeks 4-8
chondrification centers for vertebral column develop
week 6
primary ossification centers for vertebral column develop
week 7
ribs form (sclerotome), tail regresses, limbs rotate/enlongate, digits and face develop,
week 8
produces floating ribs
hox9
prevents rib formation
hox 10
from parietal layer of lateral plate mesoderm
sternum formation
sacralization of vertebrae
Hox11
rostral neuropore doesn’t close
Anencephaly
causal neuropore doesn’t close
spina bifida
malformed pelvis, underdeveloped lower limbs, 250X more in pregestational diabetics
Caudal dysgenesis
form of CD, mermaid syndrome
Sirenomelia
Loss of function: ribcages with all ribs attacted to sternum
Mutation of Hox9
Loss of function: lumbar and sacral vertebrae with ribs. Gain of function: Thoracic vertebrae without ribs
Mutation of Hox10
LoF: Sacral vertevrae that donot fuse. GoF: vertebrae at various levels fusing
Mutation of Hox 11
fracture of pars interarticularis
Spondylolysis
Hox11 gain of function mutation at L5
Sacralization of L5 vertebra
bone ossification centers (wk 12), ext genetalia visible (wk 12), swallowing and urine formation (wk 10), respiratory movements (wk 15)
Weeks 9+ (fetal period)
weeks 24 - 28
Sound and light recognition
