Yes, mammals have yolk sacs. Although they may not be as easily noticeable as the yolk in a chicken egg, it is still there. The yolk contains proteins and fats needed for the embryos further development.
yes
three yolk sacs means three babies.
Some babies live off a mucus the mother excretes or secretes, some babies are born with their own yolk sacs, and many are just on their own from birth.
In mammals through placenta and in reptiles and birds from yolk .
The allantois, yolk sac and part of chorion.
Left over or unused nutrients. This will drop off as does the umbilical cord on a mammals new born.
Mammals (with the exception of the Monotremes) are formed in the womb and fed by the mother through the umbilical and not dependant on the yolk sac.
The allantois, yolk sac and part of chorion.
Neither, alveoli are the air sacs within the lungs in mammals (singular alveolus).
Some babies live off a mucus the mother excretes or secretes, some babies are born with their own yolk sacs, and many are just on their own from birth.
The yolk of an egg is the yellow/orange part. Some adjectives that you can use to describe the yolk of an egg are thick and glossy.
An egg yolk is the yellowy orange part of an egg. You can see a picture of an egg yolk in some cookery books and on the Inmagine website.