Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes form a random pattern.

哺乳动物将营养物质输送到骨细胞的微小管道是平行排列的，而鸟类的管道则是随机排列的。

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Those who quickly became pregnant again were also less likely to have a pregnancy form in their fallopian tubes, a dangerous condition.

VOA: special.2010.08.11

They found that a small amount of aspirin suppressed the way the cells form tubes.

VOA: special.2009.10.20

The yarns were made by pulling sheets of nanotubes from "forests" of the tubes and twisting them to form a coiled structure - much as yarn is made from wool.

BBC: Nanotube yarns twist like muscles

Fifteen-metre long steel tubes are being hammered into the seabed to form foundations for Weymouth harbour wall.

BBC: Weymouth harbour wall: Warning over repair noise

For both modes of crystal fibre, the pattern of holes is generated by stacking hollow glass tubes a millimetre or so in diameter to form a rod several centimetres thick.

ECONOMIST: A new approach to making optical fibres