Wikipedia:Featured picture candidates/Leaf epidermis

Leaf epidermis[edit]

Reason: A very interesting SEM image that takes something very ordinary (the surface of a tobacco leaf) and reveals it to be some sort of crazy alien world. Trichomes and stomata are visible, adding to its encyclopedic value.
Articles this image appears in: Leaf, Epidermis (botany), perhaps could be added to trichome or stoma
Creator: Louisa Howard (Dartmouth electron microscope facility)

Support as nominator --Calliopejen1 (talk) 22:10, 21 June 2008 (UTC)[reply]

After nominating, I've noticed that there are other equally good (better?) images in various leaf galleries linked from here. If others want to click around and see if there are better ones, I would gladly consider alternates. Calliopejen1 (talk) 22:19, 21 June 2008 (UTC)[reply]

Strong objection This leaf appears not to have been cleaned prior to fixation for the SEM, chemically fixing a lot of crap onto the surface of the leaf. The cells were also not dried well, as the guard cells and the cells in between appear wrinkled, shrunken, and distorted, the opposite of what should be achieved by fixation. Here's a link to what properly fixed plant cells look like.[1] They're not collapsed, wrinkled, and shrunken. The focus is poor, the depth of field limited, it's hard to figure out what was focused on. Focusing at 200X on an SEM is not hard enough to allow for this micrograph to be out of focus throughout. There is nothing featurable about this. I will look at the page and see fi there are usable ones on that page. --Blechnic (talk) 22:21, 21 June 2008 (UTC)[reply]
- It occurs to me that you might have learnt in school that desiccated cells shrink, wrinkle, and close their stomata. Maybe you just forgot what you learnt... Papa Lima Whiskey (talk) 00:38, 22 June 2008 (UTC)[reply]
  - They don't do that much if they're properly fixed for the SEM, which is the entire purpose of the fixation process, i.e., gaining images like the one I linked to above, which maybe you didn't learn about. In order to view a biological organism under the SEM, such as a leaf, the surface must first be cleaned with biologically suitable buffer, which wasn't done for this image, then the leaf is sliced while still in the buffer to preserve the tissue as best as possible, then fixed in a buffered fixer, then secondarily fixed, then dehydrated, then, usually for SEM, put in a critical point dryer, the purpose of which is to prevent as much of this dessication, shrinking, wrinkling and closing of the stomata as possible. That is why it only took a two second search to find a suitable SEM example of a leaf and its stomata, because the protocols are fairly routine by now, 2008, and accomplished with very little equipment that every biological SEM lab has available. So, a guick search on google, and one of the first image returns is an SEM of cells that didn's "shrink, wrinkl,e and close their stomata," is this magic? No, it's phosphate buffer, buffered glut, osmium textroxide, buffer, ethanol/alcohol, etc., as needed, and CPD. --Blechnic (talk) 03:13, 22 June 2008 (UTC)[reply]
  - PS Be brave, click on the link above, see what an excellent, featured image of leaf epidermal cells under an SEM should look like. --Blechnic (talk) 03:14, 22 June 2008 (UTC)[reply]
    - Yes, with the stomata fully open. Papa Lima Whiskey (talk) 19:55, 24 June 2008 (UTC)[reply]
      - Yes, so it appears what you learned in school was wrong. But the difference between this image with the stomata fully open and the poorly preserved one, as any plant electron microscopist will tell you, and as is obvious to even the amateur, is that you can see the plump juicy guard cells inside the open stomate in the one I linked to. Now that's a secondary electron micrograph of a leaf! It's not necessary to be an expert in electron microscopy to be able to see excellence or its lack. Just the dirt and crap all over this micrograph that wouldn't be allowed if it were a photograph should have been enough to say no.
      - Yup, open stomata and visible guard cells, not-dessicated. --Blechnic (talk) 23:43, 24 June 2008 (UTC)[reply]
        So what, in your opinion, does a desiccated plant cell look like under SEM? :) Papa Lima Whiskey (talk) 11:23, 25 June 2008 (UTC)[reply]
        It depends upon how and when it was dessicated, and to what degree, what the plant is, a lot of things. This image just looks like someone picked it far too early before getting it in fixative--its looks like a dessicated plant under SEM, so I don't know what you're asking after I've said that's a problem with this image. That's not the only problem with this image, though, so again, I'm not sure what your point is. --Blechnic (talk) 14:03, 25 June 2008 (UTC)[reply]
Support. This is an informative and attractive image that, to me as someone with very limited technical experience with SEM, seems of comparable quality to other good SEM images I've seen. It may be, as Blechnic says, that there are technical flaws relative to what is possible with SEM. However, we are not yet blessed with an overabundance of attractive, high-resolution electron microscopy.--ragesoss (talk) 22:00, 22 June 2008 (UTC)[reply]
- The first part of FPC is "Is of a high technical standard." This is of not just low, but very low technical quality. We actually do have some excellent SEMs, and adding low quality SEMs to Wikipedia isn't going to be a magnet for better quality ones. This image is not of publishable quality. It has charging artifacts due to poor coating, the specimen was not properly fixed, the image was shot at probably the wrong working distance, and it's not in focus anywhere. So, how is it that we have to accept an out of focus micrograph, just because we don't have many? Did you even bother to look at the one I linked to? That's what a micrograph of leaf epidermal cells should look like. --Blechnic (talk) 02:36, 23 June 2008 (UTC)[reply]
  - The one you linked to is a very small image, probably created at a very different magnification level. This image is far more valuable for the encyclopedia than the one you link to. It's one thing to create a nice crop section, and another to create a high-resolution image than encompasses many interesting features. The focus is also actually very good throughout, I thought...it's comparable to the SEM pollen FP we have (which comes from the same Dartmouth collection). It may no longer represent the cutting edge in SEM (I wouldn't know), but I think it's the best or one of the best of the leaf images on the Dartmouth site and, on a basic aesthetic and informative level, meets the FP criteria. (Some of the images of other leaf types have somewhat plumper features, so I'm not convinced that the "dessication" isn't in part a difference between the kind of leaf here and the one in your link.)--ragesoss (talk) 11:09, 23 June 2008 (UTC)[reply]
    - Blechnic has offered a very detailed technical criticism, and unless someone with comparable technical knowledge can refute it, we should not accept the image. I don't think an image should be accepted on the grounds that it looks cool and laymen won't be able to identify its flaws. As a layman myself, I would want any scientific image I see to accurately reflect the subject and to be of the same quality scientists would use in the lab. Fletcher (talk) 14:19, 23 June 2008 (UTC)[reply]
      - On the other hand, this image is hosted by the Dartmouth electron microscopy facility and was created by a scientist who created at least one other SEM image that we decided (and I don't think anyone has disputed) meets our FP criteria. I wouldn't characterize Blechnic's comments as detailed technical criticism; it seems more like speculation (possibly well-informed) about the technical features of the image. In any case, we accept flawed images all the time when, as a whole, they meet the FP criterion. We certainly don't require normal photography to meet the highest possible technical standards, just high technical standards. The idea that there is one way that a micrograph of leaf epidermal cells should look like seems very fishy to me as well, considering the wide range of possible methods for preparing samples, which scientists use variously for different purposes. The Dartmouth facility is showing off these images...why would we assume that these are not "of the same quality scientists would use in the lab?" I think we have strong evidence of just the opposite.--ragesoss (talk) 15:23, 23 June 2008 (UTC)[reply]
        It's not speculation, I've worked as a biological electron microscopist, and the classes I took to get the work, for Papa's information, don't say that cells are dessicated and ugly, they teach you methods to minimize the dessication and change. It's not "detailed technical criticism" because most of you don't have the background for the detailed technical criticism, but I would be glad to go into all the details. It's simply a very bad micrograph. The one of pollen is in another league, an excellent, well-done SEM of pollen. I have no idea why Dartmouth is showing off these rather bad micrographs, but I would be glad to e-mail the facility director and discuss the quality of this micrograph with him/her, or ask at the microscopy list serve for details from other microscopists just why Dartmouth displays these, or what they'd think if Wikipedia put one on their main page. This is a really crappy micrograph, and no one at Dartmouth is going to say its equivalent quality to the pollen one.
        
        The point is not to offer up the other image as an alternative FPC, but to show how cells can look, and how a micrograph can and should look. This Dartmouth one is t-ball in comparison to it and to the pollen one's major league ball park. --Blechnic (talk) 15:51, 23 June 2008 (UTC)[reply]
        
        PS, Yes, it could be a less plumped up species in generally, or it could have been gathered poorly, rather than the issue during sample preparation, none of this removes the dirt, the charging (not too bad, but bad enough to require photoshop), or the poor depth of field. Also, look at the upper right: plump, unwrinkled cells. This is how I can tell what they were supposed to look like, because they look like that in part of the image. --Blechnic (talk) 16:14, 23 June 2008 (UTC)[reply]
        What do you think of the other Nicotiana images at [2]? To my eye the stomata do appear less "wrinkled" (indicative of not being dessicated?) than in this FP candidate. And the FP candidate does seem out of focus in places (two trichomes emerging from the left side). I agree there appears to be some debris on the cells, more noticeable when you zoom in. What is 'charging'? Fletcher (talk) 16:23, 23 June 2008 (UTC)[reply]
        Charging is a build up of electrons on the surface due to an inability for the excess electrons to go to ground due to a poorly done conductive coating. It gives big blank white spots on the micrograph. Almost all biological samples will have some charging, particularly if they have as much topography as this, because of the difficulties of coating all the nooks and crannies, even though the specimen coaters are designed to spin at an angle to get most areas. I will look at the other leaves later on. --Blechnic (talk) 16:26, 23 June 2008 (UTC)[reply]

Not promoted MER-C 03:24, 29 June 2008 (UTC)[reply]