The orientation for larger tissue specimens without complicated margins or stratified layers is to find the cut surface. Most of these specimens will be embedded flat on this cut surface so that the cut surface is placed flat against the block face (bottom, most recessed surface of the mold). Your main concerns will be getting the specimen as flat as possible and leaving a border of paraffin surrounding the outside edge of the tissue. Placing any dense or rigid tissue in the block face at a slight angle within the embedding mold is helpful. This will aid with microtomy.
Examples of tissue types that might be easiest to cut at a slight angle are the uterus body, thyroid, and prostate gland wedges. Large fatty pieces, such as large sections of breast tissue or lipomas, may not have a distinct cut edge but should be embedded to show the greatest surface area. It is also important to leave a heavy paraffin border to help contain the fatty tissue and hold the section together on the water bath during microtomy.
