Spina bifida, a condition in which the spinal cord is not completely enclosed by the spinal column, is the result ofMultiple choice question.the inability of the fetus to add baby fat during the fetal period.problems in neural tube development during the embryonic period.a slower rate of cell differentiation in the period after conception.the failure of the zygote to appropriately attach to the uterine wall during the germinal period.

A mother has recently learned that her infant has been diagnosed with spina bifida.  During tertiary care of the infant, she asks how this could have happened. Which nutrient will you suggest was lacking during gestation? A. Calcium B. Vitimin D C. Folic Acid D. Vitamin K

Neurulation refers to the early formation of the nervous system in vertebrate embryos.  It begins when the notochord, a rodlike mesodermal structure, induces neural tube and neural crest cell formation in a different germ layer called the ectoderm.Neural tube defects (NTDs) arise from abnormalities in the development of the neural tube and can range from mild to severe, depending on which portion of the tube is affected.  Spina bifida, a form of NTD, is divided into three categories.  The most serious subclassification of spina bifida is myelomeningocele, which occurs when the lower spine fails to close and leaves the spinal cord and nerve roots in the lower back damaged and exposed.NTDs are thought to be caused in part by folate deficiency.  Folate plays a critical role in normal cell division and growth as it is a necessary coenzyme for DNA synthesis and methylation.  Mutations in several genes involved in folate metabolism have been associated with an increased risk for NTDs.  It has been hypothesized that folate decreases NTD risk by ameliorating oxidative stress, thereby reducing damage to developing cells in the embryo.  Certain maternal conditions, such as high blood glucose, increase the risk of NTD development by enhancing embryonic oxidative stress during crucial developmental periods.A study was conducted to examine how supplementation with folic acid, the dietary form of folate, affected pregnant women who were identified with preexisting diabetes, pregestational obesity (another risk factor for NTD), or no preexisting conditions (control group).  Higher folic acid intake decreased the incidence of embryonic NTDs among pregnant women with diabetes but no significant effect was found for pregnant women who were obese.Adapted from Parker, S.E., Yazdy, M.M., Tinker, S.C., Mitchell, A.A., & Werler, M.M. (2013). The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida. American journal of obstetrics and gynecology, 209(3), 239.e1–239.e2398. Question 25The germ layer that gives rise to the notochord also gives rise to which of the following cell types?A.Alveolar cellsB.OsteocytesC.MelanocytesD.Islet beta cells

Neurulation refers to the early formation of the nervous system in vertebrate embryos.  It begins when the notochord, a rodlike mesodermal structure, induces neural tube and neural crest cell formation in a different germ layer called the ectoderm.Neural tube defects (NTDs) arise from abnormalities in the development of the neural tube and can range from mild to severe, depending on which portion of the tube is affected.  Spina bifida, a form of NTD, is divided into three categories.  The most serious subclassification of spina bifida is myelomeningocele, which occurs when the lower spine fails to close and leaves the spinal cord and nerve roots in the lower back damaged and exposed.NTDs are thought to be caused in part by folate deficiency.  Folate plays a critical role in normal cell division and growth as it is a necessary coenzyme for DNA synthesis and methylation.  Mutations in several genes involved in folate metabolism have been associated with an increased risk for NTDs.  It has been hypothesized that folate decreases NTD risk by ameliorating oxidative stress, thereby reducing damage to developing cells in the embryo.  Certain maternal conditions, such as high blood glucose, increase the risk of NTD development by enhancing embryonic oxidative stress during crucial developmental periods.A study was conducted to examine how supplementation with folic acid, the dietary form of folate, affected pregnant women who were identified with preexisting diabetes, pregestational obesity (another risk factor for NTD), or no preexisting conditions (control group).  Higher folic acid intake decreased the incidence of embryonic NTDs among pregnant women with diabetes but no significant effect was found for pregnant women who were obese.Adapted from Parker, S.E., Yazdy, M.M., Tinker, S.C., Mitchell, A.A., & Werler, M.M. (2013). The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida. American journal of obstetrics and gynecology, 209(3), 239.e1–239.e2398. Question 27Undifferentiated gastrula cells presumed to give rise to neural tissue were transplanted from a donor frog embryo into a host frog embryo.  The cells were transplanted among undifferentiated host gastrula cells presumed to give rise to epidermal tissue.  Both host and donor embryos were allowed to develop following the transplant and gave rise to two normal embryos.  What was the purpose of this experiment?A.To determine which cells in the gastrula ultimately give rise to epidermal tissueB.To determine if cell specialization is influenced by communication between cellsC.To determine how developmental fates of cells are determined during blastula formationD.To determine whether cell differentiation could be reversed based on embryonic location

Neurulation refers to the early formation of the nervous system in vertebrate embryos.  It begins when the notochord, a rodlike mesodermal structure, induces neural tube and neural crest cell formation in a different germ layer called the ectoderm.Neural tube defects (NTDs) arise from abnormalities in the development of the neural tube and can range from mild to severe, depending on which portion of the tube is affected.  Spina bifida, a form of NTD, is divided into three categories.  The most serious subclassification of spina bifida is myelomeningocele, which occurs when the lower spine fails to close and leaves the spinal cord and nerve roots in the lower back damaged and exposed.NTDs are thought to be caused in part by folate deficiency.  Folate plays a critical role in normal cell division and growth as it is a necessary coenzyme for DNA synthesis and methylation.  Mutations in several genes involved in folate metabolism have been associated with an increased risk for NTDs.  It has been hypothesized that folate decreases NTD risk by ameliorating oxidative stress, thereby reducing damage to developing cells in the embryo.  Certain maternal conditions, such as high blood glucose, increase the risk of NTD development by enhancing embryonic oxidative stress during crucial developmental periods.A study was conducted to examine how supplementation with folic acid, the dietary form of folate, affected pregnant women who were identified with preexisting diabetes, pregestational obesity (another risk factor for NTD), or no preexisting conditions (control group).  Higher folic acid intake decreased the incidence of embryonic NTDs among pregnant women with diabetes but no significant effect was found for pregnant women who were obese.Adapted from Parker, S.E., Yazdy, M.M., Tinker, S.C., Mitchell, A.A., & Werler, M.M. (2013). The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida. American journal of obstetrics and gynecology, 209(3), 239.e1–239.e2398. Question 29Compared to newborns without NTDs, a newborn diagnosed with myelomeningocele would most likely have exhibited which of the following during gestation?A.Lower frequency of cell damage at critical developmental periodsB.Lower cellular concentrations of free radicalsC.Higher levels of anti-apoptotic transcription factorsD.Higher incidence of apoptosis

Neurulation refers to the early formation of the nervous system in vertebrate embryos.  It begins when the notochord, a rodlike mesodermal structure, induces neural tube and neural crest cell formation in a different germ layer called the ectoderm.Neural tube defects (NTDs) arise from abnormalities in the development of the neural tube and can range from mild to severe, depending on which portion of the tube is affected.  Spina bifida, a form of NTD, is divided into three categories.  The most serious subclassification of spina bifida is myelomeningocele, which occurs when the lower spine fails to close and leaves the spinal cord and nerve roots in the lower back damaged and exposed.NTDs are thought to be caused in part by folate deficiency.  Folate plays a critical role in normal cell division and growth as it is a necessary coenzyme for DNA synthesis and methylation.  Mutations in several genes involved in folate metabolism have been associated with an increased risk for NTDs.  It has been hypothesized that folate decreases NTD risk by ameliorating oxidative stress, thereby reducing damage to developing cells in the embryo.  Certain maternal conditions, such as high blood glucose, increase the risk of NTD development by enhancing embryonic oxidative stress during crucial developmental periods.A study was conducted to examine how supplementation with folic acid, the dietary form of folate, affected pregnant women who were identified with preexisting diabetes, pregestational obesity (another risk factor for NTD), or no preexisting conditions (control group).  Higher folic acid intake decreased the incidence of embryonic NTDs among pregnant women with diabetes but no significant effect was found for pregnant women who were obese.Adapted from Parker, S.E., Yazdy, M.M., Tinker, S.C., Mitchell, A.A., & Werler, M.M. (2013). The impact of folic acid intake on the association among diabetes mellitus, obesity, and spina bifida. American journal of obstetrics and gynecology, 209(3), 239.e1–239.e2398. Question 24Neural crest cells migrate away from the neural tube to give rise to most of the peripheral nervous system.  Given this information, would neural crest cells be involved in the pathology of myelomeningocele?A.Yes; neural crest cells secrete signals that directly inhibit neural tube closure.B.Yes; neural crest cells fail to differentiate into the posterior spinal cord.C.No; neural crest cells continue to differentiate into glial cells of the brain.D.No; neural crest cells continue to act normally as temporary migratory cells that give rise to other cell types.