Fetus development

Uterus The small, hollow, pear-shaped organ in a woman s pelvis. This is the organ in which a fetus develops. Also called the womb, [nih]... 

Retinoic acid, available as an oral commercial preparation for the treatment of severe cystic acne (Accutane) has been one of the great successes in dermatology. However, it is not without side effects, some of which are severe. Oral retinoids are potent teratogens, and approximately one-fourth of all exposed fetuses develop birth defects. Their teratogenic potential has led to strict guidelines governing their use in women of child-bearing potential. Other side effects, such as elevated liver function tests, elevated serum lipids, and nyctalopia have also limited their use (43). 

There is an opinion, that mechanisms of adverse effects on fetus development include transmission of chemical substances from the father to an embryo through a seed liquid, so-called pass-through "infection" of mother to an embryo - the substance brought by the man from a workplace or in domestic conditions. Besides, harmful chemical substances at man s workplace can induce genetic mutations. 

This idea needs emphasis. As the embryo and fetus develop in the womb, the developing entity is continually interacting with its local environment, just as a child or adult interacts with his or her local environment. There is nothing automatic about the development of any embryo, and that includes the human embryo and its later form, the human fetus. 

What I have tried to elaborate in this book is the reality that no fetus develops in isolation from the community around it. 

Although for years it has been published that the human fetus develops in the absence of thyroid hormones, there is increasing evidence of the active transfer of maternal thyroid hormones from the mother to the human fetus. 

Providing up-to-date information about the influence of iodine deficiency on fetus development during pregnancy, child growth and development. 

Precautions Highly toxic to earthworms and some fish. Poison by swallowing. Mildly toxic by breathing. An animal teratogen (abnormal fetus development). Caused reproductive effects in animal studies (infertility or sterility or birth defects). A human mutagen (changes inherited characteristics). A skin irritant. EPA was ordered by courts to revoke approval as food additive in 1992. 

Precautions Use at a moderate level not in excess of the amount required. Caused tumors and abnormal fetus development in animals. Frequent cause of allergic reactions. 

Precautions A definite carcinogen (causes cancer). An animal teratogen (abnormal fetus development). Moderately toxic to humans by swallowing. Various effects on the body by swallowing include liver changes, respiratory effects, and constipation. An eye irritant. 

The LID fetuses developed goiter, and their thyroidal total iodine was 4.7 % of that of LID + I fetuses. The concentrations of T4 and T3 in different embryonic and fetal samples are shown in Figs. 8 and 9, where they are compared to data from age-paired samples obtained from C and T dams. Before onset of fetal thyroid function (11-day-old embryotrophoblasts and 17-day old fetuses) T4 concentrations are decreased by LID to a degree comparable to that of concepta taken from T mothers. T3 concentrations did not differ initially from those of the LID + I group. By 17 gd, however, T3 concentrations were lower both in the fetus, and placenta (not shown). Once fetal thyroid function starts, important differences become apparent between fetuses from T and LID dams. The activated secretion of T4 and T3 by the thyroid in fetuses from T mothers is able to compensate for previous differences related to maternal hypothyroidism, at least as far as the brain is concerned. But this is not possible for fetuses faced with a very low iodine supply, and cerebral T3 is quite low. Similar results were later obtained in another experimental series ... 

If only a very low number of fetuses develop in the pseudopregnant recipient, the resultant fetuses may be too large for natural delivery and a Caesarean section must be performed. The pups are fostered to mothers with natural pups of a similar age. 

Robinson, S.R., J.M. Arnold, N.E. Spear W.P. Smotherman. 1993. Artificial nipple promotes conditioned opiod activity in the rat fetus. Develop. Psychobiol. 26 375-387. 

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