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| | How Rats and Miceand Probably HumansRecognize Odors |
 | | Each olfactory neuron in the nose has a long fiber, or axon, that pokes through a tiny opening in the bone above it, the cribriform plate, to make a connection, or synapse, with other neurons. |
 | | A round, knob-like structure, the olfactory bulb is quite large in animals with an acute sense of smell but decreases in relative size as this ability wanes. |
 | | In the olfactory epithelium of the nose, Axel and Buck's groups found, neurons that make a given odorant receptor do not cluster together; instead, these neurons are distributed randomly within certain broad regions of the epithelium, called expression zones, which are symmetrical on the two sides of the animals' nasal cavities. |
| www.hhmi.org /senses/d/d130.htm (688 words) |
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