Special Problem

• Teratology is the science that studies the causes, mechanisms, and patterns of abnormal development
• Developmental disorders present at birth are called congenital anomalies, birth defects, or congenital malformations
• Congenital anomalies are of four clinically significant types: malformation, disruption, deformation, and dysplasia
• Major congenital anomalies are those that are incompatible with survival, life-threatening, or seriously compromise an individual's capacity to function normally in society
• 3% of all live-born infants have a major anomaly
• Single minor anomalies are present in about 14% of newborns
• Major anomalies are more common in early embryos (up to 15%) than in newborns (3%)
• Malformation is a primary structural defect resulting from a localized error of morphogenesis
• Disruption is a specific abnormality that results from the disruption of normal developmental processes
• Deformation is an alteration in the shape/structure of a previously normally formed part
• Syndrome is a recognized pattern of malformations with a given etiology
• Dysplasia is abnormal growth or development of a tissue or organ
• Teratogens are exogenous agents that may cause developmental defects
• Teratogenesis is a process with a threshold-level effect
• Teratogenicity is a manifestation of developmental toxicity representing a particular case of embryo/fetotoxicity
• Causes of congenital anomalies include teratogens such as drugs, chemicals, infections, ionizing radiation, and maternal factors
• Basic principles in teratogenesis include critical periods of development, dosage of the drug or chemical, and genotype of the embryo and mother
• Consequences of exposure to teratogens include death, malformation, intrauterine growth retardation, functional defects in the newborn, and normal newborn
• Egg is self-contained external development encasement for the embryo
• Female reproductive tract components include ovary, infundibulum, magnum, isthmus, uterus, vagina, and sperm storage sites
• Embryonic development can be monitored through the eggshell
• Incubation issues include temperature regulation, humidity control, turning of eggs, and candling for development assessment
• Malpositions and hatching problems in chicks can include head malpositions, oversized embryos, unretracted yolk sacs, and various abnormalities like spraddle leg, curled toes, and pasty butt
• Day 1:

  • Putting eggs in the incubator
• Day 2 - 6:

  • Rotating the eggs until Day 6
• Day 7:

  • Checking the fertile eggs through candling
  • Marking the blunt side of the egg with a pencil
• Teratogen preparation:

  • Options for teratogen solution: 0.1ml, 100 uL, 200 uL, 300 uL, 400 uL, 500 uL, 0.5 ml = 500 uL, 50 uL
  • Making a small opening at the blunt side using a hacksaw blade
  • Using 50 uL of the teratogen solution or NSS
• Day 6:

  • Introduction of the teratogen using a tuberculin syringe (0.5 cc) at 50 uL for the experimental group while NSS for the control group
  • Allowing the eggs to stay at a standing position for 24 hours
• Day 7 - 10:

  • Continuing to turn the eggs
• Day 11 - 21:

  • Waiting for the eggs to hatch and evaluating based on Measuring Chick Quality: Quantitative Scoring (Tona et al., 2003)
  • Taking photos of the developed chicks
  • Ensuring at least 9 chicks per group should be alive
  • Performing the statistical analysis
• Teratology

  • science that studies the causes, mechanisms, and patterns of abnormal development
• Congenital anomalies or birth defect or congenital malformation

  • development disorders present at birth
• Four clinically significant types of congenital anomalies

  1. malformation
  2. disruption
  3. deformation
  4. dysplasia
• Congenital malformation

  • are structural defects present at birth; may be gross or microscopic, on the surface of the body or within it, familial or sporadic, hereditary or nonhereditary, single or multiple (Warkany 1947)
• A major congenital anomaly is one that is incompatible with survival, life-threatening, or seriously compromises an individual´s capacity to function normally in society (Otake et al.,1990)