A Brief History of the Female Body by Emera Deena;

Author:Emera, Deena;
Language: eng
Format: epub
Publisher: Sourcebooks, Incorporated

Different dimensions of placental variety: overall shape (top); folding of placental and uterine membranes (middle); invasion into the uterus and blood vessels (bottom). Across mammals, there is some mixing and matching of states in each dimension.

Just focusing on one aspect of the placenta—how deeply it invades the uterus—we think the earliest placental mammals had a moderately invasive placenta, thanks to those newly evolved invasive trophoblast cells. But then the descendants of this ancestor played around with the default mode in interesting and unexpected ways. In some groups, like the one to which cows and horses belong, the placenta became less invasive and is essentially barred from breaching the mother’s uterine lining. The ability of these species to prevent placental invasion in the uterus may have had farther-reaching effects, specifically in how they manage cancer, as we’ll discuss in chapter 8. At the other extreme is the ape placenta, including and especially our own, which became so invasive that trophoblast cells reach the muscle layers of the uterus. These are two ends of a continuum. And I’m describing only one of many placental dimensions, the others of which are also variable.

Why did this astonishing variation emerge? Mother-child conflict is likely a big part of the answer, which I’ll dig into in the next section.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.