Figure 1.

Matrix layers highly enriched in the washed extracellular matrix fraction. At top, a Stage 12 egg chamber consists of a large yolk-filled oocyte, degenerating germ-line nurse cells, and a thin layer of somatic follicle cells that synthesize the eggshell. The lower diagram illustrates the oocyte surface matrix and vitelline membrane layer of the eggshell that bound the perivitelline space in which the dorsoventral protease cascade acts. Fixed components of this space, as well as the outer chorion layer of the eggshell and the basement membrane underlying the follicle cells, are highly enriched in the matrix preparations used in this study, while yolk, other cytoplasmic components and nuclear components are excluded.11