Fruit fly pupae (probably Drosophila)

[rjlittlefield]

Given free choice, I would have preferred a different color background.

But this is what my wife handed to me, in the form of a tomato that had been sitting on our kitchen counter for too long.

So, relentless red is what you get!

Long ago I deliberately raised a bunch of similar things, but I don't recall ever looking very closely at the pupae.

So I was surprised when I put these things under a scope and saw such well developed spiracles at both ends.

In addition to the front end spiracles and tracheae, this view nicely shows the larval mouth hooks that appear to be retained inside the last larval skin that has turned into a puparium. It also shows two slightly different ages of pupae, illustrating what I gather is progressive condensation of the internal structures to form the strongly segmented body of the adult. (Google image search offers https://ars.els-cdn.com/content/image/3 ... 846884.jpg , with a link to https://www.sciencedirect.com/topics/ag ... upariation , where I have read only the abstract.) That white structure in the center of the lower pupa would move periodically, as we'll see later. Fortunately the movement did not degrade the stacked result very much.

Switching now to crossed-eye stereo...





Here is that movement I mentioned, animated from 10 successive frames in the stack.



Shot with Mitutoyo 5X NA 0.14 objective on Raynox DCR-250 tube lens, so about 3.1X, on Canon R7 (22.2 mm sensor width), step size 0.020 mm, 113 frames. Two electronic flashes through mylar tracing film.

--Rik

[rjlittlefield]

Following up with later stages...

Here are pupae almost ready for adults to emerge. Their normal posture is to be stuck to substrate on the ventral surface. I have flipped one on its side so we can see the developed wings. The long red line down the side of that one is just dried tomato juice, representing the boundary of where it was stuck to the tomato before I flipped it.



Adults, female first and then male. These images have different scales; in real life the male is noticeably smaller than the female.





Adult female with empty pupal cases and some fresh eggs.



These are the eggs, seen much closer up in crossed-eye stereo. I was surprised to learn that Drosophila eggs have long extensions called "dorsal appendages" or "respiratory filaments" that provide buoyancy and facilitate gas exchange when the eggs are laid in soupy stuff. Here they're mostly stuck to other eggs so they look like attachments of some sort, but a few of them are standing up in a more functional position. At the top of the image, there are a couple of empty collapsed shells for eggs that have already hatched.





--Rik

[MarkSturtevant]

A good series! All of this is very familiar to me, with my former life doing research on Drosophila development. Many, many hours at the dissecting microscope and microscope. Those were good times, though.

[JayMcClellan]

Wow, lots of interesting details on those stereo pairs. And I threw out some rotten tomatoes just yesterday; maybe I should retrieve them and take a closer look...

[Sym P. le]

Doh! Nikon Small World raises you by 1,000. Never mind, I still love your RL vignettes.