Hi Jill,
           We normally use a Long ZN in the first instance, and if
necessary follow up with a Schmorl's. Trouble is Schmorl's stains a
number of things. Other methods you could try are Sudan Black B ,
Gomori's Aldehyde Fuchsin or PAS ( some lipofuscins stain weakly )
Normally the Long ZN is all we require { for human tissues - no idea
with regard to other species :¬)  }.  Haven't heard of using a Prussian
Blue before though ?
	Hope this helps,
		Alex. Brown
		Crosshouse Hospital
		Kilmarnock ( 2nd top of the Scottish Premier League )
		Scotland.