Birefringence in ovule walls of Asarum canadense
This is a polarized light transverse image under crossed polarizers of a carpel in the Gynoecium of Asarum canadense, or wild ginger. Birefringent material is present in the ovule walls as shown by the bright (white) spots outlining the wall edge. These are reported to be calcium oxalate crystals. There are also optically active xylem present in this image. In that case, optical activity is the result of ordered cellulose.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 48 hr. Dehydrated in 35, 50, 75, 85, 95, 99 % IPA in water, 6 hours each min. Infiltrated in xylene saturated with Paraplast for 2 days, followed by 2 changes of melted Praplast for 2 hours each. Embedded in Paraplast. Sectioned on a Spencer 820 microtome at 11 micron. Cleared in Xylene 2X, 10 min each. Rehydrated 99 (10 min), 95, 85, 70 % IPA, 2 min. each. Stained Gill's Hematoxylin 20 sec. Washed 3 min running water. Blued 0.05 % lithium carbonate 30 s. Water rinse 1 min. Stained 1 % aq. Eosin-Y 1 min. Dehydrated 99 % IPA 2 min. Cleared 2X xyene 5 min each. Mounted with DEPEX.
Photographed on a Spencer 42 petrographic polarizing microscope using an original magnification of 100X, using a Sony NEX 5N with a Leica MIKAS 1/3X adapter.
Birefringence in ovule walls of Asarum canadense
This is a polarized light transverse image under crossed polarizers of a carpel in the Gynoecium of Asarum canadense, or wild ginger. Birefringent material is present in the ovule walls as shown by the bright (white) spots outlining the wall edge. These are reported to be calcium oxalate crystals. There are also optically active xylem present in this image. In that case, optical activity is the result of ordered cellulose.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 48 hr. Dehydrated in 35, 50, 75, 85, 95, 99 % IPA in water, 6 hours each min. Infiltrated in xylene saturated with Paraplast for 2 days, followed by 2 changes of melted Praplast for 2 hours each. Embedded in Paraplast. Sectioned on a Spencer 820 microtome at 11 micron. Cleared in Xylene 2X, 10 min each. Rehydrated 99 (10 min), 95, 85, 70 % IPA, 2 min. each. Stained Gill's Hematoxylin 20 sec. Washed 3 min running water. Blued 0.05 % lithium carbonate 30 s. Water rinse 1 min. Stained 1 % aq. Eosin-Y 1 min. Dehydrated 99 % IPA 2 min. Cleared 2X xyene 5 min each. Mounted with DEPEX.
Photographed on a Spencer 42 petrographic polarizing microscope using an original magnification of 100X, using a Sony NEX 5N with a Leica MIKAS 1/3X adapter.