When I was in college, I was employed in a work-study job as frog-feeder. Actually, I started as a salamander-feeder, but when the funding ran out I switched. Talk about transferable skills! Anyhow, in both jobs I had the highly-intellectual task of wiggling small slices of liver in front of amphibian mouths. The frogs were actually oriental fire belly toads (Bombina orientalis). Note: There really is no taxonomic distinction between toads and frogs; they're all anurans. If you want to compare the two, here and here are a couple links to get you started. The toad colony was the project of Mark Ellinger, the Southern Illinois University Zoology Department Embryology Professor. I loved frogs and toads long before I went to college, but my experience there enhanced my love of all things anuran. I really don't remember why Dr. Ellinger kept fire bellies rather than the much more common frog studied in developmental biology, the african clawed frog (Xenopus), but I'm glad he did, fire-bellies are a whole lot prettier.
Okay, here's a story for you. One of the fun things about fire belly toads is that you can induce them to breed by injecting a small amount of human chorionic gonadotropin (HCG) into the dorsal lymph sac. Biosupply companies, I was told, acquire HCG extracted from the urine of pregnant women. I guess there is enough similarity between human HCG and some frog molecular equivalent to allow a cross-species effect. By morning, after injecting both the male and female, they were mounting and laying eggs. Kewl. Then we could watch the embryonic development on a dissecting microscope. It was fascinating to watch the fissures form in the dividing embryo, the invagination of the cells, and the eventual development of the tadpole. I recall explaining this process to a couple of friends of mine. They seemed surprisingly interested in the HCG. "You can get this stuff?" one asked. "Well, yeah, we stock it in the lab," I responded. Then it struck me what he was getting at, "NO! You can't have any! And it wouldn't work on humans anyhow!" Sheesh. Some people. (Actually, HCG is used clinically as an ovulation inducer, but that's a far cry from expecting "results" from slipping it into someone's drink.)
By the by, let me digress here with a rant about the HCG diet program that some nefarious medicos are still using to swindle people out of their cash. The HCG diet was championed by Albert T. W. Simeons who published a book in 1954 entitled "Pounds and Inches." The rationale behind HCG and weight loss is that HCG signals the hypothalamus to move nutrition to the developing embryo. Thus, when it is injected, or sometimes administered orally, in conjunction with a 500 calorie a day diet, the recipient loses weight. Five humdred calories a day! Who wouldn't lose weight! There are even homeopathic concoctions of HCG. Which means that they take something that doesn't work--and dilute it until it isn't even there. Quack! Quack! Quack! ('scuse me, I would say I have a frog in my throat, but that would be an insult to frogs.) The FDA is onto these scammers. If you want more info, check here.
Okay, enough about that, back to frogs. It really is much more impressive in person, but I found a couple of time-lapse vids of frog development and one very amusing one about some "true facts." Enjoy.
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Fire Belly Frogs. Awesomely beautiful (And they know it.)