Abstract
Yellow yolk spheres vary in size by their site in the yolk and the difference of the hen egg (Mineki and Kobayashi,1997; Mineki,1999). Whether the sizes of yolk spheres are influenced by the weight of eggs and how many yolk spheres are packed within the yolk were examined.
Commercial eggs were weighed and steamed. The transverse sectional area, maximum width and maximum long dimension of yolk spheres in the inner, middle and outer layers of yolks were measured by image processing techniques.
The transverse sectional areas of the spheres ranged from 3.20×103 to 9.88×103μ m2. The maximum width ranged from 60 to 99μ m. The maximum long dimension ranged from 71 to 124 pm. They were smaller in the outer layer and larger in the inner layer than in the middle layer.
The sizes of yolk spheres were directly correlated to the weight of the whole eggs and yolks. Smaller yolks contained smaller yolk spheres, and larger yolks contained larger yolk spheres.
The number of yolk spheres within a yolk was calculated from the transverse sectional areas of the yolk and yolk spheres.
The number of yolk spheres within a yolk was estimated to be about 1.8×107, regardless of the egg weight.
