What is the effect of prolonged fixation on tissue samples?

Prolonged fixation can result in brittleness of tissue samples, which is a crucial factor to consider when preparing histological sections. When tissue is exposed to fixatives for extended periods, the proteins and cellular structures become overly cross-linked and dehydrated. This excessive fixation can lead to a loss of the tissue's natural elasticity and moisture, causing the samples to become stiff and fragile. Consequently, during slicing or sectioning for microscopic examination, these samples may break or crumble, making it challenging to obtain smooth, continuous sections.

In contrast, while fixation is essential for preserving cellular architecture and proteins, the ideal fixation time must be carefully balanced to avoid the adverse effects associated with excessive fixation. It's important to note that prolonged fixation may not enhance the clarity of the sections or staining quality, as these processes can be negatively impacted by tissue brittleness.