English: Large-area tomographic reconstruction of an intercellular space near the edge of an HIV-1–infected crypt from BLT mouse colon. The movie begins with a summary of the region defined in the volume: an intercellular space separating two adjacent cells (dark green and brown) near the edge of an HIV-1–infected crypt. HIV-1 buds (blue with magenta cores) were present on both cells, demonstrating that both were infected human cells. The tomographic reconstruction of the same area shown after the summary consisted of four serial 300 nm sections, each imaged as two-frame dual-axis tomograms to encompass a volume of 1.4 µm×2.9 µm×1.2 µm. The intercellular space contained ≥300 free, mature HIV-1 virions and no free immature virions. No structural evidence of direct cell-to-cell viral transmission was present in the volume. This reconstruction supports the assumption that virion pools were not necessarily a consequence of the juxtaposition of human and murine cells within the BLT mouse system. Instead pool formation and infection by free virus may occur even when adjacent cells were HIV-1 targets, further suggesting that maturation of HIV-1 occurs quickly following scission from the host cell.