Fetal

In an interesting medical application, the formation of a stable black foam film from amniotic fluid can be used as an assessment of fetal lung maturity [206]. 

DI = deionized water PBS, phosphate-buffered saline HSA, human semm albumin essential medium + 10% fetal bovine semm. 

FCS, fetal calf semm and DMEM, Dulbecco s Eagles minimum... 

In laboratory tests, appHcation of DMAC to the skin of pregnant rats has caused fetal deaths when the dosages were close to the lethal dose level for the mother. Embryonal malformations have been observed at dose levels 20% of the lethal dose and higher. However, when male and female rats were exposed to mean DMAC concentrations of 31,101, and 291 ppm for 6 h per day over several weeks, no reproductive effects were observed (6). 

Antibodies have been generated which produce immunoassays that discriminate between GH-V and GH-N. These assay systems have shown that the secretion of GH-V becomes elevated at about three weeks of pregnancy and increases to approximately 15 ng/mL near term (8). The physiological role of GH-V is uncertain. Genetic deficiency of GH-V does not adversely affect pregnancy or fetal development (9). GH-V is a potent growth-stimulator but possesses considerably less lactogenic activity than GH-N (10). There are no clinical appHcations (ca 1993) for GH-V. 

Each of the endoscopic imaging procedures is relatively risk free and painless when performed by competent and weU-trained individuals using a local anesthetic. Eetoscopy has the highest risk. There is a 10% increased probabiUty of premature deUvery and 10% higher fetal loss rate. 

Myxedema and goiter are the main conditions for which thyroid preparations are indicated. The treatment of cretinism is difficult because it is recognized only at or after birth. Even if this disease could be diagnosed m utero, thyroid hormones do not readily cross the placental barrier. In addition, the fetus, as does a premature infant, rapidly deactivates the thyroid hormones. The halogen-free analogue DlMlT [26384-44-7] (3), which is resistant to fetal deiodinases, may prove useful for fetal hypothyroidism (cretinism). 

Stannous chloride, an FDA-approved direct food additive with GRAS status, has also been extensively studied (59—62). In three FDA-sponsored studies, it was determined that stannous chloride is nonmutagenic in rats when administered orally up to 50 mg/kg to pregnant mice for ten consecutive days, stannous chloride has no discernible effect on nidation or on maternal or fetal survival and, when administered orally at 41.5 mg/kg to pregnant rabbits for 13 consecutive days, it produced no discernible effect on nidation or on maternal or fetal survival (63—65). 

The biological activity of various vitamin E forms was estabUshed by the fetal resorption assay ia tats and is assumed to be appHcable to humans. The results of some human studies may iadicate that the ratio of 1.36 underestimates the biological activity of the RRR form relative to the all-rac form of a-tocopheryl acetate (10—12). 

Nutritional Requirements. The nutrient requirements of mammalian cells are many, varied, and complex. In addition to typical metaboHc requirements such as sugars, amino acids (qv), vitamins (qv), and minerals, cells also need growth factors and other proteins. Some of the proteins are not consumed, but play a catalytic role in the cell growth process. Historically, fetal calf semm of 1—20 vol % of the medium has been used as a rich source of all these complex protein requirements. However, the composition of semm varies from lot to lot, introducing significant variabiUty in manufacture of products from the mammalian cells. 

Studies in which pregnant rats and mice were exposed to 1250 ppm of methylene chloride for seven hours a day on days 6—15 of gestation indicated no significant maternal, embryonal, or fetal toxicity (34). Methylene chloride was shown to be nonteratogenetic to either animal at the concentration studied. 

Other toxicological effects that may be associated with exposure to benzyl chloride based on animal studies are skin sensitization and developmental embryo and/or fetal toxicity. A 1980 OSHA regulation has estabhshed a national occupational exposure limit for benzyl chloride of 5 mg/m (1 ppm). Concentrations of 160 mg/m (32 ppm) in air cause severe irritation of the eyes and respiratory tract (68). 

Figure 1 The major hormones involved in growth and funetion of the fetal/neonatal testis illustrating how exogenous, environmental oestrogens eould disrupt the normal balanee of these meehanisms.

Figure 2 Key events in fetal/neonatal life whieh predetermine reproduetive funetion of the adult human male. Note that the Sertoli eells are involved in the orehestration and eo-ordination of all of the key events. The relationship between the key events indieated and disorders of male reproduetive development and funetion are indieated in boxes.

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