Mechanisms of regulation of the capillary bed in the human chorionic villi.

The purpose of the present researches was to confirm the hypothesis that in the human placenta the microcirculation is subjected to humoral control, because of the absence of innervation in the chorionic villi and the ability of the capillaries to contract themselves. Chorionic villi were incubated in presence of vasoactive substances, Histamine, Serotonin, Bradykinin, Dopamine, Enkephalin Prostaglandins. After incubation, the specimens were fixed and embedded in resin. Semithin sections were submitted to a computerized analysis for the evaluation of the ratio between surface of capillaries and surface of the villus. The results confirmed that in the control of capillaries in the human placenta most of the tested substances show a specific action, dose- or time-dependent.