Ward R T
Tissue Cell. 1978;10(3):525-34. doi: 10.1016/s0040-8166(16)30346-9.
Secondary yolk precursor complexes are differentiated from primary yolk precursor complexes in that little or no background matrix or small vesicles are present and that electron-dark, amorphous yolk protein fills the precursor at a very early stage of growth. Secondary precursors are formed in two ways; from multivesicular bodies or from the fusion of smooth-surfaced endocytotic vesicles. Ultimately, fusion of secondary precursors with multivesicular bodies makes them indistinguishable from primary precursors. Precursors are called yolk platelets when they are mainly crystalline with only a small amount of amorphous yolk protein present. The structure of the crystal is particulate with a spacing of 70--85 A. At high resolution, the particles are seen to measure approximately 20 X 60 A. The chemical composition and interpretations of studies of the crystal structure are discussed.
次级卵黄前体复合物与初级卵黄前体复合物的区别在于，几乎没有背景基质或小泡，并且在生长的非常早期阶段，电子密度高的无定形卵黄蛋白就充满了前体。次级前体以两种方式形成：来自多泡体或来自光滑表面的内吞小泡的融合。最终，次级前体与多泡体的融合使它们与初级前体无法区分。当它们主要为晶体且仅存在少量无定形卵黄蛋白时，前体被称为卵黄小板。晶体结构是颗粒状的，间距为70 - 85埃。在高分辨率下，可以看到颗粒的尺寸约为20×60埃。本文讨论了晶体结构的化学成分和相关研究的解释。
