A few images from tonight's slide-making

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A few images from tonight's slide-making

#1 Post by mrsonchus » Fri Aug 30, 2019 8:23 pm

Hi all, I cut some sections yesterday from Sunflower stems in LS and from some nice Dandelion roots in both LS and TS. These I cut at a far thicker section than my usual 5-10µ range. I sectioned these at a huge 20µ thick! Like slicing bread! :D

This was to try to preserve intact as much of the vasulature as possible - the xylem and phloem vessels and sieve-tubes respectively, as well as fibers and tracheid/fibers. The LS sections are difficult to get sufficiently parallel to the vessels to give a good long run of intact vessel but not impossible. The main problem at 20µ I have found in the past, but not quite so much with these sections as it happened, is that they have a tendencey to adhere poorly to the slide, and to lose strands of material during de-waxing and staining of the slides pre-mounting. Mounting itself, in my usual 'Omnimount' synthetic-resin mountant, doesn't cause any detachment as long as I'm careful placing the coverslip....

Anyway, I stained most of them with aqueous 0.05% Toluidine-blue as it has such a high 'bang-for-the-buck' value due to it's metachromatic properties, and I've found from experience that it makes a lovely job of LS sections, especially those rich in vessels, and even more especially with root sections in both LS and TS. I stained a few with Safranin and Fast-green combinations also, as this well-known combination always gives good results.
At the moment I'm looking at the cell-wall pit types of both primary and secondary walls, especially those of the aforementioned xylem and phloem vessels and sieve-tubes. The improved resolution of my BX40 has made this pursuit possible in a far more effective manner than I was previously able to achieve with my beautiful Leitz Orthoplan, even with it's Apochromatic objectives...

So, a few nicely-coloured images at quite low magnification, these slides as imaged are barely one-hour from having their coverslips mounted! No real point (or safety for the slides....) in using the high-mag objectives at this first-look stage.

This is a TS through a group ot Dandelion roots, the two large roots have diverged from a single root, the smaller are I think lateral roots also sectioned transversely. The 'explosion' of xylem cells in the center of the roots is quite a sight. This section I stained with Safranin and Fast-green, and old favourite combination for me.

Here's a longitudinal section, also stained with Safranin and Fast-green, through the root at a different position. You can just about make out 2 lateral roots making their way out from the center of the root (which is where lateral roots originate unlike lateral branches that originate ner the surface of stems). As the laterals are moving outwards to eventually grow through the root's tissue to break through the surface as a root, they are caught in TS as their path in this section is a (more-or-less) horizontal one, towards the vertical main root's surface of course...

Oh yes, here's a colourful section, stained with Toluidine-blue, longitudinally (i.e. in LS section) through a Sunflower's stem.

Toluidine-blue gives different colours for different tissue-types, and is as mentioned, 'metachromatic'... A very vivid stain is always easy with such thick (relatively) sections as these of 20µ....

Here are a couple of higher-mage (40x I think), I was holding my breath with the focus with the essentially 'wet' slides!
These are the pits at the tapering ends of what I think are tracheids, in a Sunflower-stem LS. The books actually mention that the pits then adjacent may appear under the microscope to merge and look like on longer 'slit-like' pit, and here for the first time I'm able to see this detail. If you look carefully you'll see the adjacent pits appearing to merge!

This image shows the secondary cell-wall (blue) and the primary cell-wall (purple) which form a pit - seen face-on as it were, complete with the perforations of the primary cell-wall - stained darkly. At least that's what I think is shown, I haven't had time yet to consult the tomes for a complete assessment.

Oh, for those that may be interested in the lab setup, a few images.
The slides mounted this evening and the two wax-blocks they were sectioned from,

Back under cover to harden after these sneaky images....

The rest of the sections I cut yesterday, in their drying positions yet to be mounted, apologies for the blurry image - I think I left the camera on 'macro mode'.... :oops:
These will keep me busy this weekend! :D :D

I hope you like these, I'll post a few higher-mag images when the slides are a bit safer to use, tomorrow probably....
John B

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