Glycogen
Definition
A polysaccharide energy store present in vaginal epithelial cells. It is released when cells are lysed and can be detected by periodic acid-Schiff staining or iodine reagent. Glycogen is also the primary carbon source for Lactobacillus in the vaginal microbiome.
- Type
- Polysaccharide energy store
- Location
- Vaginal epithelial cells
- Detection methods
- Periodic acid-Schiff staining, iodine reagent
- Biological role
- Primary carbon source for vaginal Lactobacillus
Common questions
Why is glycogen detection used to identify vaginal fluid in casework?+
Glycogen-rich epithelial cells are characteristic of the vaginal lining, so a positive PAS or iodine reaction on cells from a stain supports the source being vaginal rather than another body fluid, though the reaction is not fully specific to that source alone.
How does glycogen relate to the vaginal microbiome?+
Lactobacillus species that dominate a healthy vaginal microbiome metabolise glycogen released from lysed epithelial cells into lactic acid, maintaining low vaginal pH, a separate biological role from its use as a forensic identification marker.
What are the limitations of glycogen-based tests for vaginal fluid?+
Glycogen presence alone is not conclusive since related epithelial cell types elsewhere in the body can also stain positive, so glycogen testing is typically used alongside other markers such as microbial DNA profiling for a stronger identification.
Related terms
- Ehrlich's Reagent
- A solution of para-dimethylaminobenzaldehyde in acid. It reacts with urobilinogen and related pyrrole-containing compounds to produce a pink-red colour, used as a...
- Ferning
- The arborisation pattern formed when cervical or vaginal mucus dries on a glass slide, produced by sodium chloride and glycoprotein crystallisation. Visible...
- Periodic Acid-Schiff (PAS) Reaction
- A histochemical staining method that oxidises polysaccharides (including glycogen) to produce aldehydes, which are then detected by Schiff reagent as a magenta...
- RSID-Vaginal Mucosa
- Rapid Stain Identification of Vaginal Mucosa. An immunochromatographic lateral-flow assay using antibodies targeting proteins specific to human vaginal epithelial cells, providing higher...
- Urobilinogen
- A colourless bile pigment metabolite produced by intestinal bacteria from bilirubin. It is excreted in faeces (as urobilin/stercobilin) and detected in forensic...