Fetal nervous system brain-development

Adequate amounts of folic acid are especially important in fetal development, during the first eight weeks of life following fertilization. The compound is essential to promote normal development of the fetal nervous system. Folic acid deficiencies in the mother during this period may result in neural tube defects such as spina bifida or anencephaly, a condition in which the fetus brain and skull fail to develop normally. The U.S. Centers for Disease Control and Prevention recommend that pregnant women take 600 micrograms of folic acid daily to avoid such problems. 

Iodine and thyroid hormones affect all stages of human development, from in utero life to adulthood. Iodine deficiency leads to insufficient production of thyroid hormones, which play a vital role in the process of early growth and development of many organs. During pregnancy, both maternal and fetal thyroid hormones are required for normal fetal brain development. Of them, maternal hormones constitute the main source in the first and the second trimesters, whereas the contribution of fetal hormones becomes more important in the third trimester (de Escobar et aL, 1985 Vulsma et ai, 1989). Many studies indicate that iodine deficiency and iodine-induced maternal-fetal hypothyroxinemia result in impairment of central nervous system (CNS) development during fetal and early postnatal life. 

Acute lead toxicity produces appetite loss and vomiting. Chronic toxicity leads to renal malfunction, anemia, gout, and nervous system disorders, including brain damage in children. (Lead inhibits development in fetal and child brains.) The effects are more serious for a patient deficient in calcium, zinc, or iron (see Figure 2). Available Pb + affects the structure and function of the bone marrow, where it inhibits several enzymes involved in heme synthesis. It also affects mitochondrial functions in diverse ways. It has proven difficult, however, to specify critical interactions in lead toxicity. Pb + is not particularly carcinogenic but quite toxic. Acute toxicity is dealt with by infusion of Ca +-EDTA,... 

Kruger, S., Sievers, J., Hanson, C., Sadler, M., and Berry, M., Three morphologically distinct types of interface develop between adult host and fetal brain transplants implications for scar formation in the adult central nervous system, J. Comp. Neuml., 249, 103, 1986. 

It s estimated that each cortical neuron has an average of 10,000 synapses with other neurons near and far. But these connections do not develop all at once. They are formed in the brain during fetal development, infancy, childhood, and even adulthood. The simple fact that the gross anatomy of a child s nervous system is not completely developed until about n or 12 years of age is another refutation of the idea that neurological wiring is complete at birth and therefore uninfluenced by environment. 

Since we already know that changes in the fetal environment can cause severe changes in the development of the fetal brain and nervous system, one question that pops up is whether mere brain size can explain IQ differences—brain size either determined by genes alone or brain size determined by gene—environment interactions during gestation. 

But no matter the culture, a critical phenomenon needs to be emphasized the impact of culture on the fetal environment, one environment influencing another environment, the fetal environment translating cultural forces into biological effects that shape the development of the brain and nervous system. This connection between culture and brain development is as much anthropology as neuroscience—which makes the connection intriguing and even startling. But more important is that the connection is crucial for public policy. 

The physiology and biochemistry of the human neuroendocrine system is complex, highly variable between individuals, and subject to impacts from the maternal environment. The evidence that the activity of the maternal HPA-axis influences the development of the fetal brain is clear and expected. The fetus does not develop in a bubble that isolates it from the mother the dynamics of maternal stress physiology, whether internally driven or driven by the outside world, must be a factor in the development of the fetal brain and nervous system. 

The realization that iodine deficiency in pregnancy has a pronounced effect on fetal, neonatal and childhood brain function has resulted in a large body of knowledge on the effects of thyroid hormone on brain and nervous-system development (see Grave, 1977 DeLong et ai, 1989 Stanbury, 1994 Bemal, 2002). 

While the amounts consumed rarely cause acute illness, these organophosphate insecticides (OPs) have the potential to cause long-term damage to the brain and the nervous system, which are rapidly growing and extremely vulnerable to injury during fetal development, infancy and early... 

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