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Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation, specialized cells on the dorsal side of the embryo begin to change shape and form the neural tube.
The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into the closed neural tube. In humans, neural tube closure usually occurs by the fourth week of pregnancy (the 28th day after conception). Stages of neural tube formation.
The triple test, also called triple screen, the Kettering test or the Bart's test, is an investigation performed during pregnancy in the second trimester to classify a patient as either high-risk or low-risk for chromosomal abnormalities (and neural tube defects). The term "multiple-marker screening test" is sometimes used instead.
Chromosomal abnormalities, neural tube defects, abdominal wall defects, heart defects, other major physical defects Very low risk, however there is the potential for bruising, pain, nerve damage, fainting, haematoma, bacterial infection, and bloodborne pathogen exposure.
Anencephaly is the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development. [1] It is a cephalic disorder that results from a neural tube defect that occurs when the rostral (head) end of the neural tube fails to close, usually between the 23rd and 26th day following conception. [2]
The formation of the neural tube from the ectoderm is called neurulation. The ventral part of the neural tube is called the basal plate; the dorsal part is called the alar plate. The hollow interior is called the neural canal. By the end of the fourth week of gestation, the open ends of the neural tube, called the neuropores, close off. [5] A ...
Failure of neurulation, especially failure of closure of the neural tube are among the most common and disabling birth defects in humans, occurring in roughly 1 in every 500 live births. [42] Failure of the rostral end of the neural tube to close results in anencephaly, or lack of brain development, and is most often fatal. [43]
Neural tube defects (NTD), which begin to become observable at the 28th day of pregnancy, occur when the embryonic neural tube fails to close properly, the developing brain and spinal cord are openly exposed to amniotic fluid.