Pathological study of Japanese quail embryo with acid alpha-glucosidase deficiency during early development

A pathological study was performed on the tissues of 11 Japanese quail embryos with type II glycogen storage disease (GSD II) between incubation day (ID) 3 and ID 15. Accumulation of glycogen in vacuoles derived from lysosomes was first seen in cardiac muscle at ID 3, in liver at ID 5, in wing muscle at ID 7, and in pectoral muscle at ID 10. The number and size of the glycogen vacuoles gradually increased during development, especially in cardiac muscle. Cytoplasmic glycogen particles, showing the same density as membrane-enclosed glycogen particles, were first seen as masses in cardiac muscle at ID 3, in liver at ID 5, in pectoral muscle at ID 10, and in wing muscle at ID 15. The area of cytoplasm occupied by the glycogen particles increased during development. Myofibrillar degeneration was not seen, although myofibrils appeared in disarray in the early stages, as in normal embryos. This is the first study of the development of embryonic tissues of Japanese quails with GSD II. GSD II in the Japanese quail appears to be clinically analogous to the human late (juvenile)-onset disease, although the disorder starts at very early stages in quail embryos. Therefore, Japanese quails with GSD II can provide a model for elucidating the pathogenetic process of human GSD II.