Talk:Yolk sac

Why isn't there anything about bird or reptile yolk sacs on here? The "Egg yolk" article is totally unhelpful as it's mostly about gross anatomy and culinary uses. Mind if I start a section on the avian yolk sac? 76.210.74.212 (talk) 05:46, 20 April 2009 (UTC)

It says that the yolk sac is for nourishment in "primitive" mammals. As it's in humans, does that mean it has the nourishment function only in primitive mammals? 144.32.128.14 (talk) 13:37, 27 March 2012 (UTC)

At 3 days of gestation???
The first sentence in the "In humans" section is wrong and very confusing. The yolk sac, as correctly indicated in a later section, initially appears late in the second week of embryonic development.

Giuseb (talk) 06:50, 14 December 2015 (UTC)

Wildly inaccurate article
This article makes it sound like the yolk sac functions to nourish the developing human embryo. This isn't true at all. The yolk sac is a misnomer in humans (as Moore pointed out in what appears to be the only cited source in this article) as it contains no yolk. It functions in hamatopoesis while the placenta nourishes the embryo. The function of the yolk sac varies widely across mammals (discussed in greater detail by A.M. Carter and A.C. Enders in "Placentation in mammals: Definitive placenta, yolk sac, and paraplacenta", Theriogenology. 2016 Jul 1;86(1):278-87 and in some clades it does function as a secondary placenta, but not humans. I'll rewrite this article when I have time unless someone else wants to do it first... Dubium et Libertas —Preceding undated comment added 02:41, 17 April 2019 (UTC)