High quality, continuous throughput, tissue processing

#1. Field of the Invention

#The present invention relates to the rapid, continuous flow, processing of tissue for microscopic examination, from fixation to impregnation.

#2. Description of the Related Art

#FIG. 1 is a flow chart showing that almost 24 hours elapse between the time a tissue specimen is obtained by a surgeon and the time a diagnosis by a pathologist can be prepared from microscopic examination of sections of the tissue;

#FIG. 2 is a flow chart showing that with the present invention, diagnosis by the pathologist can be made available to the surgeon who provided the tissue specimen in about 2 hours or less;

#FIG. 3 is a schematic plan view of a tissue processing facility provided in accordance with the invention;

#A process and apparatus for rapid, continuous histological processing of tissues is disclosed. The steps of fixation, dehydration, fat removal, and impregnation can be performed in less than about two hours; this allows a pathologist to evaluate samples shortly after receipt, perhaps while the patient is still in the operating or recovery room. Patient anxiety can be reduced by reducing the time required for pathological diagnosis. Rapid and continuous processing is accomplished by decreasing the thickness of tissue specimens, use of non-aqueous solutions composed of admixtures, solution exchange at elevated temperature and with agitation, uniform heating of tissues and solutions with microwave radiation, impregnation under vacuum pressure, or a combination thereof.

#Fixation, dehydration, and removal of fat are required for the preparation of tissue prior to impregnation. These steps are facilitated by trimming the tissue to a suitable size prior to processing, and using cassettes which hold such tissue blocks and allow their easy transfer between solutions for fixation, dehydration, removing fat, and impregnation.

#Fixation initiates hardening of the tissue specimen, and may preserve cell morphology by cross linking proteins and halting cellular degradation. Without chemical fixation, endogenous enzymes will catabolize and lyse the cell, and the tissue microanatomy will be altered. Such fixatives may be a ketone, aldehyde, alcohol, acetic acid, heavy metals, chromic acid, picric acid, or osmium tetroxide. Indications that fixation was inadequate can include: disassociation of tissue structures, bubbles in tissue sections, poor and irregular staining, shrunken cells, clumping of cytoplasm, condensation and less distinct nuclear chromatin, and autolysis/hemolysis of erythrocytes.