Lecture 14 - Fetal Development Flashcards
What happens in the first, second and third weeks following fertilisation to the embryo?
In the first week (3rd gestation) the embryo forms a morula then a blastocyte and implants. In the second week a bilaminar disc forms of hypoblast and epiblast. In the third week gastrulation occurs to form the trilaminar disc (ectoderm, mesoderm and endoderm)
When does organogenesis take place?
In week 3-8 post fertilisation
What are birth defects? What are the types?
Developmental disorders present at birth. Types are Structual (congenital abnormality), functional (organ dysgenesis) and metabolic (enzyme problems)
What are the three main causes of birth defects?
Genetic
Environmental
Multifactorial inheritence
What is malformation?
A congenital abnormality that has an incomplete or abnormal formation of structure. Or it is absent or has alteration of its normal configuration.
What is disruption?
A congential abnormality resulting in morphological alterations of an already formed structure.
What is deformation?
A congenital abnormality resulting from mechanical forces acting on the fetus.
What are syndromes?
A group of abnormalities with a specific known cause.
What are associations?
Abnormalities that tend to occur together but the cause is not known.
What are sequences in terms of abnormalities?
When a defect leads to a cascade of further abnormalities.
What are teratogens?
Agents that cause or predispose to a birth defect.
What are the main types of teratogens?
Drugs Environmental chemicals Infectious agents Radiation Maternal factors e.g. SLE Mechanical factors
What are the results of an insult to the fetus at different stages of development?
In the first two week will usually result in miscarriage or no effect
In the organogenesis period (3-8 weeks) the fetus is the most sensitive and it will likely result in a birth defect
in the fetogenesis period (9-38 weeks) the main effect will be on growth and functional maturation so doesnt usually lead to a birth defect.
What is the difference between meningecoele and mylomeningocoele spina bifida?
Meningocoele is herniation of just the meninges
Mylomeningocoele is herniation of the meninges and the neural tissue.
What is lemon sign?
The shape of the babies brain seen on ultrasound indicative of spina bifida. This is because the frontal lobes of the brain are being pulled on by the brain being sucked into the spinal cord.
