To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
This chapter reviews the key roles of the different layers of the maternofetal interface in supplying essential nutrients to the developing fetus before the placental circulations are fully established. Focal trophoblastic oxidative damage and progressive villous degeneration trigger the formation of the fetal membranes that remodel the uteroplacental interface. The distribution of the placental-specific protein human chorionic gonadotrophin (hCG) in yolk sac and coelomic fluid samples, and the absence of hCG mRNA expression in yolk sac tissue, suggests the secondary yolk sac (SYS) has an absorptive function. During the 10th week of gestation, the yolk sac starts to degenerate and rapidly ceases to function. The anatomy of the materno-fetal interface in the first trimester is the result of the need for a delicate balance between the metabolic requirements of the developing fetus and the potential harmful effects of oxygen during embryogenesis and organogenesis.