More than 20 years ago, two Harvard University medical researchers, Joseph and Charles Vacanti, led a team that successfully grew a human-ear-shaped piece of cartilage on the back of a lab mouse. The experiment used an ear-shaped mold filled with cartilage cells from a cow. The “ear” was first placed into an incubator, and once it began to grow, it was transplanted into the body of a nude mouse (a species of laboratory mouse with a genetic mutation that causes a degraded or absent thymus organ, inhibiting the animals’ immune system and ability to reject foreign tissues).

“Earmouse” or the Vacanti mouse, as the animal has become known, continued to grow the piece of tissue out of its back until it resembled the size and shape of a human ear. The team published their research in Plastic and Reconstructive Surgery in 1997. The experiment was designed to test the viability of growing tissues for later transplant to human patients. And just last year, human children in China suffering from a genetic defect called microtia, which prevents the external ear from growing properly, received new ears grown with their own cells—a similar process to growing the “ear” on earmouse.

The mouse with a human ear on its back may have been one of the more bizarre and visually unsettling experiments carried out on a rodent, but mice have been used for scientific experiments since around 1902, when a quirky and enterprising breeder named Abbie E. C. Lathrop recognized the animals' potential for genetic research. The first use of rats in experiments started even earlier, with records dating back to the 1850s. Scientists purchased their subjects from professional breeders known as “rat fanciers” who prized the creatures as pets for their unique coats and personalities. For decades, lab rats and mice have been used to make great scientific and medical advances, from cancer drugs and HIV antiretrovirals to the yearly flu vaccine.

Lab mice—most often of the species Mus musculus, or house mouse—are biomedical swiss army knives, with genomes that are easily manipulated for genetic studies. The physiology of the human body, however, is more closely mimicked in Rattus norvegicus, or the Norway rat, and its various strains. Rats are also easily trainable and perfectly suited for psychological experiments, especially considering their neural networks so closely resemble our own . […]

“They [rats and mice] reproduce quickly, they are social, they are adaptable, and they are omnivores, so they’ll eat pretty much anything,” says Manuel Berdoy, a zoologist from Oxford University. Additionally, the rodents’ diminutive size allows relatively easy storage in labs, and their shared evolutionary roots with humans mean the species’ genomes overlap overwhelmingly. […]

Studies with rodents address everything from neurology and psychology to drugs and disease. Researchers have implanted electronics into mice brains to control their movements, repeatedly tested the addictive properties of cocaine on mice, administered electric shocks to rodents as a negative stimulus, implanted human brains in mice skulls, and sent mice and rats scurrying through endless labyrinths of tests. NASA even keeps lab mice aboard the International Space Station for experiments in microgravity.

(Disponível em: www.thesmithsonianmag.com)

Assinale V (verdadeiro) ou F (falso) para as alternativas.

Ratos são mais apropriados para experimentos psicológicos e suas redes neurais são semelhantes às do homem.