November 08, 2004
Tonight's Blue Plate Special: Ascaris lumbricoides
We finally started into dissections in biology lab tonight. My own specimen was this rather stout, well-endowed female Ascaris lumbricoides, an intestinal parasite of humans:
I'd suspected that although our college's brand-new science center was state of the art in facilities, our gear would be knackered, so I brought my own gear (probes, pins, scalpels, various forceps, etc.) just in case. I was correct in my assessment: all the school-supplied gear was thrashed. One other guy in the lab, an Air Force PJ (USAF Pararescue) who's med-school bound, brought his own gear too; it was interesting to compare kits.
Since this specimen was pseudocoelomate in its body plan, there was no mesentary tissue to complicate the incision process. I was able to do really well with a #15T surgical blade: small enough, with a fine tip for starting an incision, but a sufficiently curved blade belly to continue incisions without nicking the viscera.
One gets the impression after laying this open and spreading its innards with a blunt probe that it is all uterus, wrapped in oviduct... two strands of Top Ramen cloaked in angel hair pasta. This thing is even more dedicated to reproduction than it is to feeding. Brrrrrr.
Posted by Russell Whitaker at November 8, 2004 11:23 PM | TrackBackSome educational wisdom from someone who had a test on intestinal helminths yesterday:
The life cycle of this worm is rather interesting: you ingest an egg then it hatches in your intestine and migrates through your body to your lungs, causing potentially lethal allergic reactions along the way. You cough it up, swallow it again then the worm grows up in your intestines and sucks out all your nutrients. It's the most common helminth infection in the WORLD probably because it's capable of laying up to 200,000 eggs per day and is transmitted through contaminated water.
random med student: I'd heard about this life cycle in lecture, but didn't pick up on the eggs/day number. Little wonder given the end-to-end reproductive tract. Thanks for the insight.
Posted by: Russell Whitaker on November 9, 2004 01:36 PM