More Lousy Muscles --- Human head louse

Cactusdave · Post by **Cactusdave** » Tue Oct 18, 2011 1:01 pm

Subtitle: Why I can't wash that louse right out'a my hair?

I took these images a while back when I first discovered stitching as a means of covering a large subject at reasonably high magnification, and before I had discovered the even more seductive delights of stacking first and then stitching. About 70 images were used in each stitch. I would like to revisit the subject with stack and stitch to squeeze some more detail out, but these will have to do for now.

The subject was a slide of the human head louse Pediculus humanus capitis by L C Clarke which dates from the 1920s. The preservation of the muscles is very good, and the slide label recommends polarisation as the method of choice for examining the slide. More information on the natural history of the head louse and its interesting relationship to the body louse here: http://en.wikipedia.org/wiki/Head_louse

The microscope was a Nikon Diaphot equipped with a LWD 0.55 Phase/DIC condenser and X10 0.25 Plan DIC objective. The camera used was a Canon 40D and images were stitched with Microsoft Image Composite Editor.

Three sets of images were obtained, conventional 'grey' DIC, full extinction 'darkfield' DIC and false colour DIC obtained by adjusting the 1/4 wave plate (De Senarmont compensator).

Conventional DIC

An 82 megapixel zoomable version is here. http://photosynth.net/view.aspx?cid=cf9 ... ecbee6d0a3

A couple of crops to illustrate detail.

'Darkfield' DIC

Big version here: http://photosynth.net/view.aspx?cid=117 ... 6564be5d62

False Colour DIC

Big version here: http://photosynth.net/view.aspx?cid=2bf ... 9e14866905

I'm not normally a fan of false colour DIC, but it does show up the muscles nicely here. The starburst of muscles radiating from the centre of the thorax is interesting. I can't find much on the anatomy of the head louse but I guess these prominent muscles are important in keeping the louse's tenacious grip on the hair, as are the claws.

Mitch640 · Post by **Mitch640** » Wed Oct 19, 2011 5:52 am

I am constantly amazed at the detail still available in a near hundred year old mount. These are all great, but for me, #4 gets the prize for the detail still left in the trachea. Simply amazing.

Cactusdave · Post by **Cactusdave** » Wed Oct 19, 2011 9:03 am

Thanks Mitch. Yes the preservation of the trachea is striking. I really should work over this slide again with stacking and stitching, and maybe even do a section at least, with a X25 objective, because there is a lot more detail to resolve.

RogelioMoreno · Post by **RogelioMoreno** » Wed Oct 19, 2011 4:58 pm

Very nice!

How did you do the darkfield DIC, with the polarizer and analyzer at crossed position?

Rogelio

Cactusdave · Post by **Cactusdave** » Thu Oct 20, 2011 12:22 am

Thanks Rogelio. I did the 'darkfield' DIC exactly as you suggest, by adjusting the De Senarmont compensator and rotatable analyser to give maximum extinction.

Wim van Egmond · Post by **Wim van Egmond** » Thu Oct 20, 2011 4:18 am

Beautiful results and those central muscles show what the this organism is designed to do. To cling as fast to its host as it can.

Wim

Pau · Post by **Pau** » Thu Oct 20, 2011 8:53 am

Dave, excellent images from a venerable high quality slide. Lots of work for an outstanding result.

Wim van Egmond wrote:...what the this organism is designed to do.

Not a photographic topic , but I would like to read adapted in place of designed, because it's a much more adequate term in Biology

Cactusdave · Post by **Cactusdave** » Thu Oct 20, 2011 12:27 pm

Thanks Wim and Pau. I have a couple more slides of lice which have well preserved musculature. I have them lined up to work on in the near future, but in the meanwhile I have some nice fleas I took a while back to keep up the itchy theme.

I'll post them shortly.