medulla
Quick Summary
The term "medulla" can refer to different structures. In the context of lichens, the medullary layer is the layer of loosely interwoven threads found just below the algal layer.1
Lichens themselves are a symbiotic association between algae or cyanobacteria and fungi. They are found worldwide and can colonize various surfaces. The composite body of a lichen is called a thallus, which can have different forms: crustose (crustlike), foliose (leaflike), or fruticose (shrubby or cuplike).2
In biology, the medulla oblongata is the lowest part of the brainstem, connecting the brain to the spinal cord. It plays a crucial role in transmitting signals and controlling vital autonomic functions like heartbeat and respiration.3
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