I do not know if this is specific: however, there is a very strong +ty in what I think are B-cells ( in white pulp) and also in plasma of blood vessels ( most evident in the larger bvs alongside the trabelculae

Note the differences in positivity/distribution between normal, atrophying and atrophied seminiferous tubules

Alexa 488 ( SOX) – Alexa 594 ( Myosin)

Positivity is confined to Nuclei of the cerebellum and discrete areas of the midbrain, pons, medulla

They give opposite positive results: which antibody is giving specific positivity? Endogenous biotin was blocked by pretreating sections in Avidin/Biotin solutions.

Positivity is confined to collagen type I fibres ( coating them) most obviuosly seen in the submucosa

Note that what appear to be medullary cells have a very strong cytoplasmic positivity ? specific? The positivity seen in the collagen of the developing skeletal muscles fibres (to the left of adrenal ) is as expected.

I used anti IgM-biotinylated  secondary ( anti IgG-biotin gave identical intensity of +ty but section quality was poor). I noted CS-+ve extracellular “plaques” in the white matter ( so are not Amyloid plaques)