Morphometric and statistical techniques were used to assess the relation of myometrial interstitial trophoblast to the uteroplacental vasculature in 27 intact hysterectomy specimens ranging from 8 to 18 weeks' gestation. It was found that the volume density of cytotrophoblast in the myometrium and in particular the proximity of such trophoblast to the placental bed spiral arteries correlated significantly with morphological alterations in these vessels. The changes included swelling of endothelium, hypertrophy of individual medial smooth muscle cells, and oedema and disruption of the architecture of the vessel wall as a time-related continuum. Some of the changes, such as swollen endothelium and basophilia of medial smooth muscle cells were noted also in spiral arteries in the non-placental bed endometrium but to a considerably less extent than in the placental bed. Intimal vacuolation was common to placental bed and nonplacental bed arteries, increased wich gestational age and can be considered as a non-specific feature. The migration of endovascular trophoblast into the myometrial spiral arteries in the second trimester occurred only when these arteries had been considerably altered in their morphology. These findings indicate that migratory interstitial cytotrophoblast probably has a role to play in the preparation of the myometrial segments of the uteroplacental arteries for the second wave of endovascular trophoblast migration that occurs in the second trimester of human pregnancy.
We have described a human term trophoblast cell culture system which synthesizes hormones de novo from their precursors. In the present report we utilized this monolayer system to show that insulin produced a dose-dependent stimulation of hPL secretion, with a significant effect at 10(-10) M insulin. At 10(-9) M concentration, insulin also inhibited estradiol secretion by the cultured trophoblast. We conclude that insulin regulates secretion of estradiol and placental lactogen by cultured human term trophoblast.
Monolayers of mouse trophoblast cells were produced after short-term culture (two to four days) of ectoplacental cone cells derived from 7.5-day-old mouse conceptuses and were then tested for phagocytic activity. Following brief intervals of coincubation with the blood stage form of Plasmodium berghei, the parasite that causes rodent malaria, cultured trophoblast cells were found to phagocytose large amounts of parasitic material. In a manner similar to that of peritoneal macrophages, trophoblast cells ingested predominantly hemozoin pigment granules, while internalization of nonparasitized red blood cells occurred infrequently. Trophoblast-mediated phagocytosis was sensitive to the inhibitory effects of cytochalasin B. The expression of this form of immunelike function by midstage trophoblastic elements may play an important role during embryogenesis by protecting the fetoplacental unit from injury by invading microorganisms or by limiting congenitally acquired infections.