What is removed through the process of trimming after embedding?

In the process of trimming after embedding, excess wax is removed. This step is crucial as it ensures that the tissue sample is precisely exposed for sectioning. During embedding, the tissue is infiltrated with paraffin wax, which provides support and structure. However, once the tissue is embedded and cooled, it is necessary to trim away any excess wax to form a block that is of manageable size and has the appropriate dimensions for cutting thin sections on a microtome. Proper trimming optimizes the visibility of the tissue and aids in achieving high-quality histological sections.

The other options do not apply to this context: excess dye and staining agents are associated with pre-embedding or staining processes, and prepared tissue blocks are not something that is removed; instead, they are the final product of the embedding process.