Multivesicular bodies and related structures of the syncytiotrophoblast of human term placenta

摘要

AbstractMultivesicular bodies and related structures of the syncytiotrophoblast of human term placenta have been studied ultrastructurally and cytochemically. Circular profiles of vesicles termed pre–multivesicular bodies (pre‐mvb's) were observed often near Golgi complexes. Multivesicular bodies (mvb's) with electron lucent matrices (L‐mvb's), mvb's with electron dense matrices (D‐mvb's), and dense bodies were also prevalent organelles of the syncytium. These organelles all exhibited dialyzed iron reactivity and staining characteristics suggesting that the organelles were related. Material within Golgi saccules, Golgi vesicles, vesicles of pre‐mvb's, and vesicles of mvb's were all reactive with osmium zinc iodide (PZI). This OZI reactivity further indicated a relationship between the organelles. The matrix of the mvb's exhibited variable reactivity for acid phosphatase (AcPase) but such activity was not encountered in Golgi elements of syncytiotrophoblast. It is suggested that the mvb's of human term placental syncytium are likely formed by aggregation of vesicles of Golgi origin into pre‐mvb's, that the pre‐mvb's are then capable of transforming into L‐mvb's, D‐mvb's, and finally into dense (residual) bodies. It is also suggested that mvb's may function in the selective hydrolysis and transport of endocytosed proteins, including globulins. Additional bodies with intense acid phosphatase activity were designated elongate bodies. Other Distinctive organelles designated dense cored spheroids were occasionally observed in