Body composition, developmental

DES (diethylstilbestrol), xiii, 106, 115, 206 detoxification, 34 developmental toxicity, 103 dibenz(a,h)anthracene, 112 diet, 5, 13-14,106 as exposure pathway, 13-14 chemical composition of, 5 effect on absorption of chemicals, 29 natural carcinogens in, 229-31 role in cancer, 116—20, 154-6 role in cancer prevention, 230 Dioscorides, 39 dioxin, xiii, 54, 164, 180 distribution of chemicals in body, 31-2 DNA damage, 150-3, 156 Doll, R. (Sir), 117-20, 155, 177 Donora, Pennsylvania, 81 dose, 16,39,48,71 absorbed, 27-31, 161 acute, 160... 

The sex chromosome composition of human males and females is XY and XX, respectively. If cells contain more than one X chromosome, all except one are inactivated. The cells of XX females contain a structure called a Barr body, which is a condensed, heterochro-matic, transcriptionally inactive X chromosome. The cells of XXY males also contain a Barr body. XXY males suffer from Klinefelter s syndrome they are usually mentally retarded, sterile, and suffer from physiological and developmental abnormalities. It is thought that extra X chromosomes must be prevented from gene expression to preserve the correct gene dosage in both males and females. 

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