Birefringence in Asarum canadense epidermus
This is a transverse section through the stem of a Horse Hair (Equisetum arvense) showing the epidermal cells. These cells walls contain silica which explains the marked optical activity and Maltese cross morphology under crossed polarizers. The blue and orange colors indicate presence of birefringent material, the purple indicates isotropic material. A bright field image is at: www.flickr.com/photos/14643312@N02/17571754339. Specimen collected along the Dowagiac River, 25 May 2015.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 48 hr. Dehydrated in IPA at 35, 50, 70, 85, 91, 95, 99 %. Infiltrated with paraplast saturated xylene 48 hr followed by 3 Paraplast baths prior to embedding in Paraplast. Sectioned 7 um thick on a Spencer 820 microtome. Cleared in xylene, 5 min, 2X. Rehydrated in 99, 95, 80, 70 %IPA. Stained in Johansen's Safranin-O, Fast Green (24 hours in Safranin-O, 15 sec. in fast green). Cleared 2 X in xylene 10 min each and mounted with DPEX.
Photographed under crossed polarizers with a lambda plate on a Spencer 42 petrographic microscope at original magnification of 430X using a Sony NEX-5N and a Leica MIKAS 1/3X adapter.
Birefringence in Asarum canadense epidermus
This is a transverse section through the stem of a Horse Hair (Equisetum arvense) showing the epidermal cells. These cells walls contain silica which explains the marked optical activity and Maltese cross morphology under crossed polarizers. The blue and orange colors indicate presence of birefringent material, the purple indicates isotropic material. A bright field image is at: www.flickr.com/photos/14643312@N02/17571754339. Specimen collected along the Dowagiac River, 25 May 2015.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 48 hr. Dehydrated in IPA at 35, 50, 70, 85, 91, 95, 99 %. Infiltrated with paraplast saturated xylene 48 hr followed by 3 Paraplast baths prior to embedding in Paraplast. Sectioned 7 um thick on a Spencer 820 microtome. Cleared in xylene, 5 min, 2X. Rehydrated in 99, 95, 80, 70 %IPA. Stained in Johansen's Safranin-O, Fast Green (24 hours in Safranin-O, 15 sec. in fast green). Cleared 2 X in xylene 10 min each and mounted with DPEX.
Photographed under crossed polarizers with a lambda plate on a Spencer 42 petrographic microscope at original magnification of 430X using a Sony NEX-5N and a Leica MIKAS 1/3X adapter.