Učestalost fantomskih stanica trebalo bi odrediti i odvojeno dokumentirati na temelju vizualnog pregleda (jer nedostatak jasno definirane glave znači da se stanice ne mogu dobro otkriti s pomoću sustava za analizu slike) najmanje 150 stanica po uzorku (za detalje vidjeti stavak 56.).
OECD (2002), “Guidance Document on the Recognition, Assessment and Use of Clinical Signs as Humane Endpoints for Experimental Animals Used in Safety Evaluation”, OECD Environment, Health and Safety Publications (EHS), Series on Testing and Assessment, No.