8/6/2019 Chrome Alum Coating of slides

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Coating:1. Chrome Alum Gelatin Solution:

Gelatin, type A, 220 or 275 Bloom -------- 1.5 gChromium potassium sulfate ---------------- 0.25 g

Distilled water ------------------------------------- 500 ml Heat the water to 60 C and completely dissolve the gelatin with the aid of a magneticstirrer. Stir in the chromium potassium sulfate (The solution should turn a pale blue). Add afew crystals of thymol as a preservative.

2. Procedure:

Dip racks of clean slides in the warm gelatin solution (40-50 C), drain the slides ontopaper tissue, and then stand the slides (covered with foil to keep off dust) on end to air dry or37 C incubator overnight. Store in dust-free container at room temperature. Throw out thegelatin mixture after use.

Mounting:

1. Paraffin Sections (up to 50um):Cut 50 um paraffin sections with the aid of warm water drops on the block using penbrash. Keep the pen brash on the block during cutting. Transfer sections to water bath(around 45 C) and allow the sections remain in water bath until they are flat (nowrinkles). Mount the sections onto gelatin-coated slides and blot gently using wet filterpaper to make section flat on slide. Air dry for 2-4 hours (longer air dry time will makesection crispy) before put into oven. Bake in oven (around 55 C) for overnight. Takeslides out of oven and air dry again for at least one hour before deparaffinization.

2. Frozen/vibratome sections (30-50um):Before or after staining of frozen/vibratome sections, mount the sections on gelatin-coated

slides and air dry overnight or 2-3 days.

Note:

This protocol has been tested successfully on formalin-fixed, paraffin embedded brain tissuesections at 50 um thick. The sections went through antigen retrieval procedure and still intactwithout detaching from slides.