Intestines of freshwater stingray embryos sampled in South America were examined histologically. During embryonic development, yolk, which is transported through the yolk stalk from the external yolk sac, appeared to be accumulating in the intestinal epithelial cells of larger embryos. The yolk (or yolk derived/originated substances) that accumulated in the intestinal epithelial cells may provide nutrients that enable the embryos to survive the vulnerable period immediately after birth.
freshwater stingray
yolk
intestinal epithelial cells
Disceus thayeri
Potamotrygon magdalenae
P. motoro