Partitioning and Exocytosis of Secretory Granules during Division of PC12 Cells

Figure 6

Ultrastructural analysis of the distribution of SGs during late stages of mitosis. Synchronized PC12 cell populations were processed for TEM. Shown are cells at anaphase (A) and telophase (B) and the respective magnified boxed areas on the right compare the density of SGs in the midzone ((A₁)/(B₁)) and the polar periphery ((A₂)/(B₃)). Please note that SGs are preferentially distributed in the cell midzone. Panel B₂ is a magnification of the boxed region in panel B. Please note the close association of an SG (red arrow) with a microtubule fiber (red asterisk) and an apparent linker structure (red arrowhead) reminiscent of a motor protein. CH, chromosome. Scale bars, panels (A) and (B), 5 μm; panels (A₁), (A₂), (B₁), and (B₃), 500 nm; panel (B₂), 100 nm.