This was originally 5 cryosections stored in antifreeze. I tipped off the antifreeze and added excess Formalin to fix overnight with gentle agitation ( at RT). I then processed sections to Pwax and cut conventionally. Immunostaining was excellent.

One may do this conversion procedure succesfully with unfixed/fixed frozen tissues

This was originally 5 cryosections  stored in antifreeze. I tipped off the antifreeze and added excess Formalin to fix overnight with gentle agitation ( at RT). I then processed sections to Pwax and cut conventionally. Immunostaining was excellent

One may substitute anti IgM with anti IgG, imho.

The non-neuronal interstitial tissue +ty in both appears to be equal. However, the neuropil ( CNS interstitial tissue) is less intensely +ve when using anti IgM-biotinylated secondary.

Comments welcome

ExCuticle: one can see plenty of goblet cells and even some secretions.

Not an “excellent” antibody( in thius application) but good  ( I can’t get a crisp +ty: this might be due to fix taking a long time to penetrate the eyeball)

However,  as this gives a similar pattern of +ty in retina ( altho photoreceptor/ganglion cell  nuclei are not as +ve as HPA ab)  and pancreas IofL cell cytoplasm ( but no nuclear +ty!)

Compare withe the excellent  HPA004174

Positivity is confined to Islet cell cytoplasm.