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Basic Anatomy and Tissue Identification

The embedding histologist must practice to develop rapid visual recognition of tissue types and be able to determine the correct orientation for each specimen using their knowledge of anatomy and tissue sampling techniques. It is often helpful to consider the reason(s) that each specimen may have been selected for submission to histology. Also, remember that clear goals are outlined for each specimen to arrive at a diagnosis based on the type of specimen and the suspected reason for the surgical procedure performed.
Gross dissection of tissue samples is determined by a pathologist or pathologist's assistant (PA). Many laboratories follow established protocols for the gross dissection of particular types and categories of specimens. Specimens are identified using a numbering system that associates a unique number with a specific patient, medical record number, and tissue sample upon receipt. The cassette containing the specimen from that unique patient and procedure is also identified with this number. This unique number is transcribed on the slanted top edge of the tissue cassette by either hand or machine, shown in the lower image. The slides prepared from the block in the histology lab from this cassette are likewise identified with this unique number, as shown in the image on the right.
Tissue is selected for microscopic examination to document important details about each specimen. Some examples of specimens that may be selected for submission to histology include:
  • All lesions grossly identified - Tissue between lesions may be included with the lesion to determine if the lesion is separate or interconnected to surrounding normal tissue.
  • Representative sections of all normal tissues or structures that are not included with suspected disease-containing sections.
  • All surgical margins, when appropriate.
  • Frozen-section remnants for permanent sections.