Re: ageing rings in sharks

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From:Barry Rittman <>
To:histology <>
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Shark denticle aging rings can be shown most easily using non-demineralized sections.
In paraffin sections the rings and reversal lines in bone can be accentuated using a modified hematoxylin and eosin. We originally used Delafield's hematoxylin and stained overnight, however can use many different formulae. The secret is a long staining in a
dilute hematoxylin.  Use1-5% hematoxylin in glass distilled water (filter before use and make up just before use). Stain progressively and replace the solution if the color weakens. Staining for several hours to overnight. Reversal lines and growth lines stain
much more strongly than the surrounding tissue. Blueing times are minimal. Generally differentiation is not required. If the background looks a little "murky"  then use a very quick differentiation in 0.25-0.5% acid alcohol.

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