Final answer:
When tau proteins detach from microtubules due to hyper-phosphorylation, microtubules disassemble, and tau can form neurofibrillary tangles, indicative of neurodegenerative conditions.
Step-by-step explanation:
When tau proteins fall off microtubules, it typically happens because the tau has become hyper-phosphorylated. This hyper-phosphorylation changes the conformation of tau proteins, preventing them from stabilizing the microtubules as they normally would. As a result, microtubules disassemble, and disassociated tau proteins may aggregate to form neurofibrillary tangles. These tangles are harmful to neurons and are characteristic of neurodegenerative diseases such as Alzheimer's disease. Immunostaining techniques can be used to visualize these tangles within neurons, highlighting their locations within affected brain regions.