LARGE GLOBOID PARTICLES IN THE COTYLEDONS OF CUCURBITA-MAXIMA SEEDLINGS

Light microscopy and transmission electron microscopy revealed the loc ation of previously identified large protein body globoids within the cotyledons of Cucurbita maxima seedlings. Large globoids formed in the three cell layers of the spongy mesophyll above the lower epidermis. The large globoids share morphological similarities to typical globoid s by being spherical and naturally electron dense, but they were appro ximately four times the size of regular globoids, ranging from 4 to 8 mu m in diameter. The formation of the large globoid particles occurre d around 3 days of seedling growth and likely resulted from fusion of a number of typically sized globoids. This method of formation was sup ported by the appearance of clusters of regular globoids prior to the formation of the unusually large globoids. The volume of a large globo id was less than the combined volume of all the typical-sized globoids found within a mesophyll cell earlier in seedling growth.