This past week I learned how to prepare specimens for scanning electron microscopy (SEM). This process requires the fixatives glutaraldahyde and osmium tetroxide, the latter of which is extremely volatile and toxic ( it can cause temporary blindness if not used under the fume hood). A myriad of other steps are required, which are largely intended to gradually remove the water from the sample. Eventually, the specimens are placed into a critical point dryer, a machine that dries the sample using the instantaneous evaporation of liquid carbon dioxide. After this, the specimens are placed in a sputter coater, a machine that coats the samples with a thin layer of gold. This metallic coat creates a surface by which electrons, emitted by a "gun", can be reflected off and be detected by the SEM. In addition to all the prep work, I also operated the SEM itself. The microscope is surprisingly easy to use, especially considering how powerful it is.
|Fig 1: A lateral view of a 10 hour old M. alaskensis larva|
|Fig 2: An anterior/posterior view of a 10 hour old M. alaskensis larva|
Figures 3 and 4 both display relatively well-developed cilia. Note, however, that in figure 3 the cilia are largely restricted to the equatorial region, along the margin of the specimen. Conversely, the larva of figure 4 clearly possesses cilia near its center.
|Fig 6: A posterior view of a M. alaskensis pilidium|
Note the dense, "furry" patches of cilia that run along the edge of the specimen in figure 5. These are the ciliary bands. Also note the apical tuft at the anterior end of the pilidium, another densely ciliated patch. Figure 6 show the interior side of the lappets (the "ear flaps"). The mouth of the pilidium is located in between these lappets.
Very commendable post. The topic seems like interesting to read..it gives me a lot of ideas and point of view specially on cell formations. Glad you have shared this.. :)ReplyDelete