Fetus, steroid conjugation

Most other in vitro or in vivo experiments, however, show little or no direct activity of steroid conjugates. Peillon and Racadot s study (1965) on the involution of LH-producing pituitary cells by dehydroepiandrosterone and dehydroepiandrosterone sulfate in the rat, and Holdens (Holden and Lozinski, 1950) results after sodium-testosterone sulfate administration to castrated rats show no efiFect of the conjugate. This was also the case in Josso s (1970) experiments on the influence of androstenediol, dehydroepiandrosterone, and dehydroepiandrosterone sulfate on the maintenance of Wolffian canals of rat fetus in culture. 

Pinzymic Systems in the Fetus Compared to the Adult and Control of the Production of Steroid Conjugates in Fetal Life. 240... 

V. Transfer of Steroid Conjugates between the Fetus and the Placenta and between the Placenta and the Mother... 

Significant ejuantities of estriol, estriol sulfate, and estriol glucuronidc are localized in the amniotic fluid (TToen et aL, 1961), and since this compartment exhibits a high sulfatase activity, it can be concluded that fetal membranes and the amniotic cavity are actively involved in the interchange of steroid conjugates between fetus and mother. 

It can be concluded that the very high sulfokinase activities in the fetus play an important role in the physiological function of active steroids but it is not yet established how these different enzymes are controlled. Xor is it yet known what the biological activity of these steroid conjugates is in this period of life, or how these steroid conjugates are transported, what is their half-life, and how they can be involved in the biological activities of steroid hormones in the fetal compartment. 

Testosterone produced by the placenta is transferred to the fetus and is conjugated mainly with sulfuric acid, but in contrast to a high sulfatase activity by the placental tissues for ester sulfates of 3/J-hydroxy-As steroids and for estrogen sulfates, the testosterone sulfate is poorly hydrolyzed by placental tissues (French and Warren, 1966). These results confirm that the sulfatase activity in the placental compartment is conditioned by the structure of the sulfate. In addition, the incubation of testosterone sulfate with a placental microsomal preparation failed to show any formation of estrogens (Cheatum et at., 1968). These last results also agree with the absence of aromatization of testosterone sulfate during pregnancy (Baulieu ef al., 1965). 

The exchange of steroid hormones between the fetus and the placenta and between the placenta and the mother is very active for both free and conjugated forms in this section we will consider the transfer system between these three compartments and also its relationship to the amniotic cavity. 

In contrast to most it-Cw, A5-C2i or estrogen conjugates, comparative studies with corticosterone and corticosterone-21-sulfate injected into the umbilical vein establish that this ester sulfate is transferred to the mother slightly more quickly than the free hormone (see Section III, D, 3 and Table IV). These studies also demonstrate that the transfer rates of the free corticosteroids from the fetus to the mother are very different after perfusion of corticosterone, cortisol, cortisone, and deoxycortisosterone into the umbilical vein at midgestation, these steroids were transferred very slowly (2-8% of the administered radioactivity is collected in the maternal urine) on the other hand, after tritiated aldosterone was perfused through the umbilical vein, 20 to 30% of the radioactivity was recovered in the maternal urine (Pasqualini, 1970). 

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