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EMBRYOLOGY TERATOGENESIS EMBRYOLOGY rubella

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EMBRYOLOGY TERATOGENESIS EMBRYOLOGY rubella Powered By Docstoc
					                          EMBRYOLOGY
                        TERATOGENESIS
   LEARNING OBJECTIVE
   At the end of lecture student should be able to know,
   What is teratology?
   Infectious agents effects.
   Torch infections effects.
   Drugs effects.
   Chemical agents effects.
   Radiation effects.
   TERATOGEN
   A teratogen is any infectious agent,drug,chemical or
    radiation that alters fetal morphology or fetal function if
    the fetus is exposed during a critical stage of




    development.
   THE RESISTANT PERIOD
   Week 1 of development.
   Is the time when the
    conceptus demonstrates the
   ’all or none’ phenomenon
 THE MAXIMUM SUSCEPTIBILITY PERIOD
 Week 3 to 8 embryonic period.
 Is the time during which the embryo is most
  susceptible to teratogens because all organs
  morphogenesis occurs at this time.
 THE LOWER SUSCEPTIBILITY PERIOD
 Weeks 9 to 38 fetal period.
 Time during which the fetus has a lower susceptibility to
  teratogens because all organs
  systems have already formed.
 Teratogens expose generally results
  in a functional derangement of an
  organ system
 INFECTIOUS AGENTS
 May be viral or nonviral.
 Viral infections may reach the fetus
  via the amniotic fluid after vaginal infection transplacentally
  via the bloodstream after maternal viremia,or by direct
  contact during passage through an infected birth canal
 Bacteria appears to be non teratogenic.
 RUBELLA VIRUS
 Transmitted to the fetus
  transplacentally.
 Risk greatest during the first
  month of pregnancy.
 Clinical menifestation.
 Fetal rubella infection results in
  the classic triad of cardiac
  defects(patent ductus
  arteriosus,pulmonary artery
  stenosis,arterioventricular
  septal defects),cataract,and low
  birth weight.
 The clinical manifestations
    include intrauterine growth
    retardation,hepatosplenomegaly,generalized
    adenopathy,Hemolytic
    anemia,hepatitis,jaundice,meningoencephalitis,eye
    involvement,osteitis,and sensorineural defects
   CYTOMRGALO VIRUS
   Most common fetal infection.
   Transmitted to the fetus transplacentally or by the virus
    ascending from the cervix during recurrence.
   Transmitted to perinates during passage through the
    birth canal or through breast milk.
   Clinical manifestations are
   Sensorineural deafness,intrauterine growth
    retardation,microcephaly,chorioretinitis,hepatospleeno
    megaly,osteitis,discrete cerebral
    calcification,mental retardation,heart
    block,bluish purple lesions on yellow
    jaundice skin.
   HERPES SIMPLEX
   Transmitted to the fetus transplacentally
    occasionally.
   Most commonly transmitted to the fetus by
    direct
   contact during passage through an infected birth canal.
   At 10 to 11days of age clinical manifestation.
   Disease localized to skin,eye,mouth.
   At 15 to 17days of age.
   CNS involvement.

 Untreated disease results in an 80%
  mortality rate and
 most survivors have neurologic
  sequele.
 The only intervention to prevent infection is delivery by
  cesarean section with in 4 to 6hours of ruture of
  amniotic membranes.
 VERICELLA ZOSTER
 Transmitted to the fetus transplacentally.
 Clinical manifestations of fetal varicella syndrome
  include
 Cicatricial(scarring) skin,digit hypoplasia,limb paresis,limb
  paralysis,hydrocephalus,mental
  retardation,microcephaly,seizure,chorio
  retinitis,
 and cataract.
 Treatment of the neonate is by
  acyclovir.
 HUMAN IMMUNODEFICIENCY VIRUS
 HIV is transmitted to the fetus through
 blood containing HIV or HIV infected lymphoid cells near
 the time of delivery after 35days of gestation.
 HIV infection does not appear to cause any congenital
  malformation but results in chronic mutisystem
  infections.
 FUNGAL INFECTIONS
 BACTERIAL INFECTIONS.
 VIRAL INFECTIONS.
 NON VIRAL INFECTIONS
 TOXOPLASMA GONDI
 Transmitted to the fetus
 transplacentaly,
 if untreated
 results in miscarriage,perinatal
 death,chorioretinitis,microceph
  aly,
 Hydrocephalus encephalomyelitis with
 cerebral calcification.
 Surviving infants are left with major neurological sequele(eg
  mental retardation,seizure,spasticity,and visual dificits)
 TREPONEMA PALLIDUM
 Transmitted transplacentally.
 Infection acquired at birth
 through contact with genital lesion in the birth canal.
 Results in miscarriage,perinatal
  death,hepatospleenomegally,hepatitis
  ,joint swelling,vesiculobullous
  blisters,nasal discharge with
  rhinitis,maculopapular rash located in
  extremities,,eye findings(
  chorioretinitis,glaucoma,cataract and
  uveitis),anemia,jaundice,focal
  erosions of the proximal medial tibia,saw tooth appearance
  of metaphysis of long bones,abnormal teeth,and acute
  syphilic leptomeningitis that may present as neck
  stiffness,and chronic meningovascular syphilis(cranial nerve
  palsy,hydrocephalus,cerebral infarction)
 TORCH INFECTIONS
 Are caused by,
 Toxoplasma.
 Rubella.
 Cytomegalovirus.
 Herpes virus.
 And other bacterial and viral infections that are grouped
  together because they cause similar clinical and pathological
  manifestations.
 DRUGS
 THALIDOMIDE
 Prescribed for pregnanat women for morning sickness.
 Drug cause limb reduction,ear and nasal
  abnormalities,cardiac defects,lung defects,pyloris
  stenosis,gestrointestinal atresia.
 AMINOPTERIN
 Used in cancer chemotherapy.
 Causes small stature,abnormal cranial ossification,ocular
  hypertelorism,low set ears,cleft palate,myelomeningocele.
 BUSULFAN
 Are alkylating agents used in chemotherapy.
 Cause cleft palate,eye defects,hydronephrosis,renal
  agenesis,absence of toes,growth retardation.
 PHENYTOIN
 Antiepileptic drug.
 Causes growth retardation,mental
  retardation,microcephaly,craniofacial defects,nail and digit
  hypoplasia.
 TRIAZOLAM AND ESTAZOLAM
 Are hypnotic drugs.
 Causes cleft palate.


 WARFARIN
 Anticoagulant.
 Causes stippled epiphysis,mental
  retardation,microcephaly,seizure,fetal hemorrhage,optic
  atrophy in fetus.


 ISOTRETINOIN
 Used in the treatment of severe acne.
 Causes CNS abnormalities,external ear abnormalities,eye
  abnormalities,facial dysmorphia,cleft palate.
 CLOMIPHENE
   Nonsteroid ovulatory stimulant used in women.
   There are reports of birth anomalies.
   DIETHYLSTILBESTROL
   Used to prevent spontaneous abortion.
   Causes hypoplastic uteruspremature labour,and cervical
    incompetance.
   ETHISTERONE,NORETHISTERONE,AND MEGESTROL
   Causes masculinization of genitalia in female
    embryo,hypospadias in males and cardiovascular
    anomalies.
   NORETHINDRONED AND LEVONORGESTROL
   Are oral contraceptive.
   Cause an increase of fetal abnormalities.
   Particularly of VACTERL SYNDROME.
   Consisting of
    vertebral,anal,cardiac,tracheoesophageal,renal,and limb
    malformation.
   NICOTINE
   Delivered to the fetus through cigarette smokiong.
   Causes intrauterine growth retardation,premature
    delivery,low birth weight,and fetal hypoxia.
   ALCOHOL
   Causes fetal alcohol syndrome,which results in mental
    retardation,microcephaly,limb deformities,craniofacial
    abnormalities,cardiovascular defects.
 OTHER DRUGS
 Tetracycline

 Streptomycin

 Phenobarbitol

 Valproic acid

 Diazepam.

 Lithium.

 Hidrochlorothiazide.

   CHEMICAL AGENTS
   Mercury.
   Lead.
   Polychlorinated biphenyls(PCBs)
   Potassium iodide.
   Bisphenol.
   Phthalates.
   Methoxychlor.

   RECREATIONAL DRUGS
   Lysergic acid(LSD) has not shown to be teratogenic
   Marijuana has not shown to be teratogenic.
   Caffeine has not shown to be teratogenic.
   Cocaine results in an increased
    risks of congenital
    abnormalities,still births,low birth
    weight,and placental abruption.
 Heroin has not shown to be teratogenic,it is the drugs
  that are taken with heroin that produce congenital
  anomalies.methadone used to replace heroin is not
  teratogenic but is also associated with severe neonatal
  withdrawal.
 IONIZING RADIATION
 ACUTE HIGH DOSE(over 250rads) of radiation results in
  microcephaly,mental retardation,growth retardation,and
  leukemia.
 AFTER EXPOSURE TO GREATER THAN 25rads classic
  fetal defects will be observed so that termination of
  pregnancy should be offered as an option.
 DIAGNOSTIC RADIATION.
 Radioactive iodine cocktails for organ visualization should be
  avoided after 10 week of gestation because fetal thyroid
  development can be impaired.
 REFERENCES.
 Internet(different sources)
 BRS(4th edition,ronald w dudek,james d fix)

				
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posted:1/27/2011
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