Steroid Synthesis in Vitro by the Placenta of the Guinea-Pig. And Progesterone Concentrations in Systemic and Uterine Plasma

Abstract

The spongy zone (SZ) syncytiotrophoblast has been identified as the prinicipal site of progesterone synthesis in the placenta of the guinea-pig. This was evident from the relatively large amounts of progesterone synthesized by the SZ from [7alpha-3H]pregnenolone and the exact correlation of SZ development and the estimated progesterone secretory activity of the placenta throughout gestation. Placental progesterone secretion started between days 20--25 of gestation when the SZ was being formed. Progesterone secretion rose to a maximum by day 30 and was maintained until at least day 53, reflecting the large amount of SZ tissue present in the placenta during this period. Secretory activity decreased simultaneously with decrease in SZ tissue, even though a decrease in progesterone concentration in systemic plasma was not evident. The results also suggested that the yolk sac was able to synthesize progesterone and metabolize steroids in vitro. Small quantities of 5-saturated C21 steroids were also synthesized by the placenta.

The subplacenta of the red-rumped agouti (Dasyprocta leporina L)

“…It has been shown for a variety of hystricognath rodents that the hormone circulates bound to progesterone-binding protein [ 24 ]. The principal site of placental progesterone synthesis is the interlobar syncytiotrophoblast [ 25 ]. This is supported by the presence there of smooth endoplasmic reticulum and mitochondria containing tubular cristae [ 26 ].…”

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“…The interlobular trophoblast is the functional equivalent of the spongy zone of murid rodents [14]. In the guinea pig it has been identified as the principal site of progesterone synthesis [15]. In addition, it is thought to synthesize progesterone-binding protein [16], which is found in the plasma throughout gestation and is unique to hystricomorph rodents.…”

Spatial Distribution of Putative Growth Factors in the Guinea Pig Placenta and the Effects of These Factors, Plasma, and Bile on the Growth and Chemotaxis ofCampylobacter jejuni

“…In mid-to late gestation, the placenta becomes a major source of progesterone production in guinea pigs, with hormone synthesis occurring in the spongy zone syncytiotrophoblast of the placental disc. 33 The yolk sac placenta is inverted in the guinea pig, with its visceral all time points, growth of IA3902 in the presence of all 3 iron-containing treatments was significantly greater than that in minimal essential medium (MEM) þ DMSO control; however, no differences were observed with the addition of either progesterone or estradiol. (b) At all time points, growth of NCTC 11168 in the presence of all 3 iron-containing treatments was significantly greater than that in MEM þ DMSO control; however, no differences were observed with the addition of either progesterone or estradiol.…”

“…In mid-to late gestation, the placenta becomes a major source of progesterone production in guinea pigs, with hormone synthesis occurring in the spongy zone syncytiotrophoblast of the placental disc. 33 The yolk sac placenta is inverted in the guinea pig, with its visceral Figure 7. Mean growth (OD 600 ) of Campylobacter jejuni in the presence of individual plasma factors at 24, 48, and 72 hours.…”