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
malformation
disruption
deformation
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)