Transport of immunoglobulin G across the human placenta.

It is wall known that Immunoglobulin G (IgG) is transported across the human placenta during gestation. Howewer the route of this transport is not clear and the aim of this thesis is to elucidate the transport pathway. A number of different methods and placental systems were employed to investigate the IgG transport pathway. 1. Human placentae were perfused with a human IgG probe using an isolated cotyledon method, 2. Dissected chorionic villi from both term and first trimester placentae were incubated in culture medium containing a human IgG probe. 3. Human placental cells were cultured and incubated with a human IgG probe. 4. Choriocarcinoma cells (BeUo) were cultured and incubated with a human IgG probe. The IgG transport process was investigated at the light microscope level using tritiated IgG, and at the electron microscope level using colloidal gold particles coated with IgG. From these investigations new evidence was discovered concerning the transport of IgG across the human placenta. In addition an extensive morphological study of the BeWo cells has provided much new information. There are clear indications in the structure of these cells, first of transformed state and secondly of their origin from trophoblast tissue. Observations are presented of the in vitro differentiation of cultured cells towards the villous state of the parent tissue. Cytoplasmic characteristics and mutual positioning of these cells was noted which were similar to those of cytotrophoblast and syncytiotrophoblast in vivo. Bulbous projections were also noted in the culture cells both attached to the tissue and floating in the culture medium. These features may be related to the budding off and depbrtation of trophoblast in vivo.