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55 Cards in this Set

  • Front
  • Back
Whats a parental imprint
Maternal genes are more important for development of the embryo, paternal genes more important for placenta.
Discuss Hydatidiform moles
Complete mole is a cystic swelling that arises from an embryo that fails to develop (essentially placenta without an embryo),
-results from fertilization of empty oocyte (has no genetic material)
Typically secretes high levels of hCG
Partial mole is a poorly developed embryo, always triploid (XXX)
Approximately 5% of moles will develop into choriocarcinoma
What is a persistent trophoblastic disease
When mole is not completely removed
invasive mole of choriocarcinoma
Why is second week of development called a week of 2's
There are 2 tissues - embryoblast and trophoblast.
Embryoblast has two levels- hypoblast and epiblast.
Trophoblast has two levels - syncitiotrophoblast and cytotrophoblast
There are 2 embryonic cavities - amnionic and yolk sac
There are two parts of extraembryonic mesoderm - somatic and splanchnic
What are two events that start formation of trilaminar embryo
Elongation of embryonic disc and formation of primitive streak
Define gastrulation
Process that defines three layers - ectoderm, mesoderm, endoderm
Describe primitive streak
Primitive streak develops on the surface of epiblast, and has two sides - cephalic and caudal which will develop in head and anus respectively. Primitive streak forms at the narrow - hea part.
What are the functions of notochord
1. It signals development of vertebral column
a. It dictates development of the CNS (inducers signal cells in ectoderm)
2. Designates the midline
3. Notochord is left over as nucleus pulposus of the IV disc
What are the two types of embryonic folding
Longitudinal (Head-Tail)
Transverse (lateral)
What plays essential role in determining body axis
Migration of the cells from primitive streak and node
Describe situs inversus
Complete - all organs are a mirror image of normal
Incomplete- dextrocardia (only heart is in the wrong place), malrotation
Also called caudal dysgenesis, insufficient mesoderm at caudal portion of the embryo - can exhibit fusion and hypoplasia of limbs and other defects
Saccrococcygeal teratoma
Persistence of primitive sreak, contain tissues from all three germ layers
What is the time frame of embryonic period
week 3-8
Buccopharyngeal membrane
Another name - precordal plate, forms mouth
bulge off yolk sac, involved in formation of urinary bladder
Neural plate
Thickening of ectoderm above notochord
Opening through which neural tube communicates with amniotic cavity, cranial closes at DAY 25, caudal closes at DAY 27
Ectodermal placodes
neural crest cells that instead of migrating get stuck
Neural crest cells give rise to...
1. Parasympathetic GANGLIA of CN III, VII, IX, X
2. Sensory ganglia of V, VII, VIII, IX, X
3.autonomic and dorsal ROOT GANGLIA
What will surface ectoderm give rise to?
Epidermis, hair, nails, cutaneous and mammary glands
What are mesoderm derivatives
LATERAL PLATE- somatic layer, near ectoderm
splanchnic - near endoderm
INTERMEDIATE MESODERM - urinary and reproductive systems
PARAXIAL - somites, spinal cord
Also vasculo and angiogenesis
Endodermal derivatives
Lining of respiratory, GI, glands
Describe generally fetal period
Indicated by external form of developing human and by presense of all major organ systems, time of rapid growth and development of organs, fetus becomes VIABLE during this period. Less susceptible to teratogens, but brain and eyes still remain in danger.
What are two important points about weeks 9-12
-week 9 - LIVER is important site for erythropoiesis (RBC formation), after week 12 at SPLEEN
-after week 9 can disstinguish external genitals as male and female
What are two important points about weeks 13-16
-sites of OSSIFICATION are evident
-EYE MOVEMENTS and EYES are facing forward
What are two importatn points about weeks 17-20
-Primary ovarian FOLLICLES are formed
-TESTES are descending
What is an important thing about weeks 21-25
Surfactant begins secretion at lungs
What is important about weeks 26-29
-Lungs are now capable of breathing
-CNS is now capable of controlling breathing and body temp
-spleen is still making blood cells, by 28 weeks blood formation shifts to bone marrow
What is important about weeks 35-38
FINISHING PERIOD- final preparations of tissues important in transition to outside world (cardiovascular and respiratory)
Describe amniocentesis
Sampling of amniotic fluid, done for the following reasons
-mother of advanced age
-mother of previous Downs child
-Parents carry chromosomal abnormality
-parents are x linked carriers
-history of neural tube defects
-parents have inborn errirs of metabolisms
too much amniotic fluid, can indicate congenital abnormality
not enough amniotic fluid, can indicate urinary defect
Describe alpha fetoprotein test
Alpha fetoprotein is a glycoprotein made in fetal LIVER, small amounts normally leak into amniotic fluid
High concentration of this protein indicates neural tube defect or ventral wall defect
Chorionic Villus Sampling
biopsy of chorionic villi, done when there is a chance of abnormality, risk of fetal loss is relatively high - 1%
Other fetal diagnostic techniques
chromatin patterns, cell cultures, ultrasound, ct, mri...
Occur during formation of structures, like organogenesis
Can result in complete or partial absense of structure, or alteration of normal configuration.
Caused by environmental/genetic factors acting independently or together
Most form 3-8 WEEKS of gestation
Morphological alteration of already formed structures due to destructive processes
-example vascular accident leading to gastric atresia or defects produced by amniotic bands
-mechanical force destruction acting on fetus over prolonged time
-example- clubbed feet caused by compression in amniotic cavity
-often involve musculoskeletal system
group of anomalies occuring together that have specific common cause
non random appearance of two or more anomalies that occur together but the common cause has not been found
Principles of teratology
1.Susceptibility to teratogens depends on genotype of fetus and how it interacts with environment, maternal genome is also important for drug metabolism, immune system, etc
2. Susceptibility varies with developmental stage at time of exposure. Most sensitive period 3-8 WEEKS, but could occur before or after
3. Depends on dose and duration of exposure
4. Teratogens have mechanisms for inducing pathogenesis - inhibition of biochemical or molecular process, pathogenesis - cell death, decreased proliferation, etc
Effect of hyperthermia
Elevated body temperatures can lead to anencephaly, spina bifida, mental retardation, microphtalmia, cleft lip and palate, limb defficiencies, omphalocele(protrusion of intestines through umbilical cord) and cardiac abnormalities
Effect of Toxoplasmosis
causes birth defects, Toxoplasmosis protozoan comes from poorly cooked meat, animals, feces in contaminated soil
characteristic manifestation- cerebral calcification
Effect of radiation
Very potent teratogen, kills rapidly prolifeating cells, can cause any type of birth defect depending on stage of development.
Can also be mutagenic
Effect of thalidomide
Anti nausea and sleeping pill during 60's, was associated with AMELIA and MEROMELIA (total or partial absense of extremities), rare hereditary abnormality
Effect of amphetamines
CNS deffects
Effect of alcohol
Fetal alcohol syndrome- part of fetal alcohol spectrum disorder, structural defects, growth defficiency, mental retardation
Alcohol related neurodevelopmental disorder- less severe then FAS
Incidence is 1/100
Effect of isoretinol
analogue of vitamin A, causes VITAMIN A EMBRYOPATHY. Drug prescribed for treatment of cystic acne, highly teratogenic, cna produce any type of malformation.
Effect of hormones
ANDROGENIC - synthetic progestins used to prevent abortion, cause masculinization of female genitalia
ENDOCRINE DISRUPTORS - interfere with normal actions of hormones in development. Synthetic estrogens cause dysfunction of CNS and reproductive system
Cortisone- cleft palate
Should not take BCP
Effect of diabetes
High incidence of stillbirths, neonatal deaths, abnormally large infants, congenital malformations. Long standing diabetes - 80% chance of birth deffect.Different deffects including serenomelia.
Effect of phenylketonuria
Disease of mother where she is defficient of enzyme called phenylalanine hydroxylase, increases serum concentration of phenylalanine
Infants are born with mental retardation, microcephaly and cardiac defects.
Effect of obesity
Pre pregnancy obesity if BMI >30 kg.m sq., 2-3 times more risk of neural tube defect.
Also increased risk for heart defects, omphalocele and multiple anomalies
Effect of mercury
Multiple neurological symptoms resembling cerebral palsy. Contains in fish, or mercury containing pesticides.
Describe techniques used for fetal therapy
FETAL TRANSFUSION- in case of fetal anemia, needle is inserted into umbilical cord vein and blood is transfused directly to fetus
MEDICAL TREATMENT- can be done through mother and crosses placenta or by intramuscular injection
FETAL SURGERY - placing shunts in utero, or can operate ex utero to repare life threatening problems