Last night's Tuesday Talk at Culture at Work was by Dr Chris Ormandy of the Garvan Institute in Sydney. He discussed his latest research into breast cancer, with lots of images of gorgeous mouse mammaries (not furry porn, but microscope images of branching milk ducts in mice of various ages and stages of lactation). In particular, we learned about the gene called Elf5 that seems to have a role in switching off the proliferation of cells in the mammary ducts and may therefore be a clue to stopping the growth of cancer.
Once again, I was struck by the resemblance of structure at the microscopic scale to macroscopic features on Earth and in space (I have blogged about this before).
Dr Ormandy showed alveolar proliferations that look like bunches of grapes on a vine or clusters of cherry blossoms on a branch, and branching mammary ducts that looked like river deltas or the root system of a tree. When I asked him about the similarities of the structures at all scales, he said, "It's all about maximising surface area. Whenever you need to transport liquid efficiently around a system, you use a branching formation." (That may not be an exact quote -- I didn't write it down because my hands were full with a glass of wine. Which might be another reason why it's not an exact quote.)
This NASA image is of a Russian river delta in summer: perhaps you are looking at Mother Earth's mammary gland.
NASA/GSFC/LaRC/JPL, MISR Team.