Equistetum sp. sporangiophore
Transverse section of a Equistetum sp. strobilus (spore producing structure) under crossed polarizers. The strobilus as found is shown at: www.flickr.com/photos/14643312@N02/18511410355/. The specimen is from the edge of the Dowagiac River.
This image shows how the sporangiophores (top) join the stem (bottom). Two sporangia with still developing spores are at the center. Note that the tapetum is still present around the developing spores. Three xylum bundles are evident in the stem at the very bottom.
This is probably one of the most optically active botanical sections I have prepared. The spiral lignified walls of the sporangia are evident. However with the exception of the pores, most all other cell walls show birefringence. Equistetum contains silica and this likely the source of the birefringence in areas other than the xylem and the sporangia walls.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 24 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 Paraplast 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), 90 (10 min.), 85, 70 % IPA, 2 min. each. Stained in Johansen's Safranin-O Fast Green. Cleared 2X xyene 5 min each. Mounted with DEPEX.
Photographed on a Spencer 42 petrographic polarizing microscope using an original magnification of 30X, using a Sony NEX 5N with a Leica MIKAS 1/3X adapter.
Equistetum sp. sporangiophore
Transverse section of a Equistetum sp. strobilus (spore producing structure) under crossed polarizers. The strobilus as found is shown at: www.flickr.com/photos/14643312@N02/18511410355/. The specimen is from the edge of the Dowagiac River.
This image shows how the sporangiophores (top) join the stem (bottom). Two sporangia with still developing spores are at the center. Note that the tapetum is still present around the developing spores. Three xylum bundles are evident in the stem at the very bottom.
This is probably one of the most optically active botanical sections I have prepared. The spiral lignified walls of the sporangia are evident. However with the exception of the pores, most all other cell walls show birefringence. Equistetum contains silica and this likely the source of the birefringence in areas other than the xylem and the sporangia walls.
The protocol was as follows. Specimens fixed in FAA (formaldehyde, acetic acid, ethanol) 24 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 Paraplast 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), 90 (10 min.), 85, 70 % IPA, 2 min. each. Stained in Johansen's Safranin-O Fast Green. Cleared 2X xyene 5 min each. Mounted with DEPEX.
Photographed on a Spencer 42 petrographic polarizing microscope using an original magnification of 30X, using a Sony NEX 5N with a Leica MIKAS 1/3X adapter.