Fig. 7. Production of MSP vesicles in the spermiogenesis-defective spe-8(hc50) mutant. (A) Low-power view of the spermathecal-uterine junction region. MSP vesicles (arrows) are abundant in extracellular spaces of this region. (B) High-magnfication view of MSP vesicles located in the region shown in A, from an adjacent section. (C) MSP vesicle in the spermathecal lumen surrounded by cytoplasmic debris from a lysed oocyte (arrowheads). Note, the inner ring of the MSP vesicle contains material (arrows) similar to the oocyte cytoplasmic contents. (D-I) Protrusions (arrows) from the cell body of spermatids located in the gonad arm. (F,I) Detection of MSP in protrusions. Scale bars: in A, 500 nm; in B-I, 100 nm.