Membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional.
1
In mice, Ins2 is imprinted and paternally expressed in the yolk sac.
2
All six ovarian yolk sac tumors showed diffuse immunoreactivity for glypican-3.
3
Chemotherapy of yolk sac tumor heterotransplanted to nude mice was studied.
4
Ovarian yolk sac tumors are common germ cell tumors usually arising in young women.
5
The patient underwent a surgical biopsy, which defined the diagnosis of yolk sac tumor.
1
This is the yelk-sac, or " umbilical vesicle," the origin of which we have considered previously.
2
The yelk-sac is reduced to a small pear-shaped umbilical vesicle; its thin pedicle, the long vitelline duct, is enclosed in the umbilical cord.
3
These vessels naturally atrophy with the degeneration of the umbilical vesicle, and the vitelline circulation is replaced by a second, that of the allantois.
4
H The vertebrae (w) have grown round the medullary tube (mr) and chorda; the body-cavity is closed, and the umbilical vesicle has disappeared.
5
The very wide opening, through which the gastric cavity at first communicates with the umbilical vesicle, becomes narrower and narrower, and at last disappears altogether.