24 October 2007

Another successful dissection

trochoidea dissection
Scale is in millimeters.

Trochoidea pyramidata is a hygromiid land snail (family Hygromiidae) widespread in southern Europe, including Turkey. Their shells can grow up to about 11 mm in diameter. One preserved specimen I had was 6.4 mm in diameter. I needed to know for a manuscript I am writing if the snails that small had fully developed genitalia. So, a good portion of last nite was spent dissecting it.

Despite the usual achy back that I got from sitting over the microscope for several hours, it was a good dissection. I was able to remove almost the entire set of the reproductive organs of the snail. Here they are pinned down and labelled. The faint scale along the right hand side is in millimeters.

trochoidea genitala


Now compare it with Germain's 1930 drawing from Faune de France, vol. 21, Mollusques Terrestres et Fluviatiles. Every part Germain's specimen had was also present in my specimen except the most proximate part, the gonad, which I didn't remove. I even had an extra muscle, presumably a retractor (no, it is not the vas deferens), attached to the bursa copulatrix that Germain didn't illustrate. The penis and the epiphallus of my specimen appear to be fully developed. The only difference is that the mucus glands (gm in Germain's drawing) are much smaller in my specimen. Does that mean that my specimen was not fully developed to reproduce yet?

GermainTpyramidata


Incidentally, I will discuss this project on Saturday at the OVUM meeting.

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