Glycogenated squamous epithelial cells as a marker of foreign body penetration in sexual assault

Nonconsensual insertion of a foreign object into the vagina, anus, or mouth in some judicial jurisdictions is synonymous with rape, and elsewhere may constitute some degree of sexual assault or battery. Few techniques, however, are available to assist the criminalist in determining whether an object has been criminally inserted. Glycogenated epithelial cells have been used as a marker for vaginal epithelium, and as such, may indicate vaginal insertion if recovered from an object. This hypothesis was tested by studying orally and vaginally inserted objects from 42 volunteers and 20 rectally inserted objects recovered from cadavers. Glycogen positivity was assayed from smears of object swabbings stained with the periodic acid-Schiff (PAS) technique. More than 75 glycogen positive cells were recovered from 39 of 42 vaginally inserted objects. Glycogenated cells were recovered from 8 of 20 rectally inserted objects (5 with more than 100 positive cells). Of 42 orally inserted objects, 32 also contained glycogen positive cells, but none with more than 28 positive cells. No glycogen positive cells were seen in skin exposed but not inserted objects. Large numbers of glycogen cells were seen in dried saliva drops. Amylase activity was not seen on 5 of 20 orally inserted shields, and thus the possibility of noninsertional saliva contamination could not be ruled out with shields yielding only small numbers of positive cells. Recovery of large numbers of glycogenated cells from foreign objects is strongly suggestive of either vaginal or anal insertion assuming amylase negativity. Glycogen positive cells are not seen secondary to glabrous skin exposure.