Dear Yafit, fixation depends on what you want to do with the tissue. For paraffin embedding I would recommend fixation in 4% PFA (freshly prepared at 4°C) over night. Regarding a protocol for paraffin embedding... maybe this link is helpful for you http://onlinelibrary.wiley.com/doi/10.1002/0471141755.pha03ds07/pdf

Dear Yafit

One of the best fixatives that I have used for general histology of the eye is the Verhoeff liquid:

Commercial Formalin 10ml

Ethanol at 95 °

Distilled water 36 ml

Picric Acid 1gr

For the final color, I suggest you execute van Gieson method.

For the skin I suggest you should use the universal fixative bouin and execute as Mallory's trichrome final staining.

Best regards Fabio

For eye i recommend 10% BNF(buffered neutral formalin).The entire eye will fix perfectly during 72-120 hours.Volume has to be 1(tissue) :15(fixative).For skin you can use also BNF or Bouin( I agree with Fabio).Bouin prepares perfectly the object to hematoxilin stain.

Bouin:

Picric acid(saturated aquueous)-75 ml

Formalin-25 ml

Glacial acetic acid-5 ml

Thank you all for your help.