Yay, anonymous donor and The Edge of Glass!
(I'm going to have to change this slide, now that PZ has staked out Comic Sans as the "crank font"...
I need to re-do it for another reason, as well--Schutte did not discuss keratinization, a change in the cells' biochemical composition which lends a golden color to the cells. Durrant , by contrast, uses the color change associated with keratin as a marker for ovulation in the panda:
A second chromic shift was consistently observed 2 days prior to ovulation when keratinized (orange) cells replaced acidophils as the majority of vaginal cells.
So here's a wonderful example of modeling physiological processes across species: Schutte details the reproductive cycle of the dog, Durrant adapts that information and applies it to the panda, and then Durrant's group and ours uses that panda information to study other species of bear.)
Anyway, this is a presentation slide that I adapted (animated, colored) from Schutte 1967 [2,3,4] for a talk on using informatics to aid in the reproduction of endangered species at the 2004 American Veterinary Medical Association conference:
What you are seeing, as you read left to right, is the change over time in the shape and color of the vaginal epithelial cells, collected by swabbing the animal. Shape changes (from more round to more irregular and from a high nucleus-to-cell size ratio to a much lower one, approaching or reaching zero in some cases), and color changes between pink/red (acidophilic) and blue (basophilic) can be seen as the cycle progresses. Although the hormone level peaks and the white and red blood cells (leukocytes and erythrocytes) are shown as well, we'll ignore those for the moment to concentrate on the changes in the colored cells in the middle of the diagram.
With a break in between, the cycle resumes at the left, and the whole process is repeated over and over again through the animal's reproductive life.
The important take-away points from this slide are the irregular borders and small nuclei of the aging cell, and the colors blue and pink (depicted above), and golden (which is also significant in pandas, but which Schutte did not address in dogs in his work).
So keeping those factors in mind, you can see why I was practically dumbstruck when I walked into a glass art studio in Fremont (a Seattle neighborhood) and noticed the piece by James Curtis titled "Little Bang":
I mean, it's all there! Large, irregular cell borders, tiny nuclei, and pink (cranberry), blue (teal), and golden color. Even the rack on which it is mounted looks like a graph over time of a cycle. I swear, if I had commissioned the artist to render mature vaginal epithelial cells in glass, he could not have carried it out more faithfully.
A huge shout-out to James and his assistant Tara for patiently working with me while I arranged financing and donation of the work to our sun bear reproductive project for auction at a later date. If you're looking for glass art, I would recommend The Edge of Glass in Seattle unconditionally for their quality, their vision, and their customer service.
And to our anonymous donor, who prefers to remain behind the scenes to put the work at the forefront, our deepest gratitude and appreciation for your help for the bears. We will keep you posted on the progress of the project.
UPDATE: I forgot, before I published this post, to mention that James told me he probably will not use the teal again, or if he does, it won't be very often--it is simply so hard to work with that it's not practical. So the bears and I did indeed get very lucky to get in there before someone else bought the piece, and we would never had known about it. I thank Mr. thalarctos for deciding to surprise me with a drop-in visit there; it worked out so much more beautifully than I could have predicted.
 Durrant B, Czekala N, Olson M, Anderson A, Amodeo D, Campos-Morales R, Gual-Sill F, Ramos-Garza J. Papanicolaou staining of exfoliated vaginal epithelial cells facilitates the prediction of ovulation in the giant panda. Theriogenology. 2002 Apr 15;57(7):1855-64.
 Schutte AP. Canine vaginal cytology. I. Technique and cytological morphology. J Small Anim Pract. 1967 Jun;8(6):301-6. No
 Schutte AP. Canine vaginal cytology. II. Cyclic changes. J Small Anim Pract. 1967 Jun;8(6):307-11.
 Schutte AP. Canine vaginal cytology. III. Compilation and evaluation of cellular indices. J Small Anim Pract. 1967 Jun;8(6):313-7.