The Amazing Armadillo by Larry L. Smith

Author:Larry L. Smith
Language: eng
Format: epub
Publisher: University of Texas Press

ARMADILLOS IN MEDICAL RESEARCH

Since early in this century, the nine-banded armadillo has been the subject of medical and scientific research in such fields as cytology, reproductive physiology, and genetics. In 1909–1911, University of Texas zoologists Henry H. Newman and J. Thomas Patterson published three papers on heredity and embryology in the nine-banded armadillo. In pioneering research on the “limits of hereditary control,” Newman and Patterson concluded that variation in the number and shape of bands over the thoraco-lumbar region, the body’s so-called “armor shield” and “a protective structure of high efficiency in an otherwise defenseless animal,” was governed by chance. In these early publications, the Austin-based scientists referred to “an extensive curio industry, making a specialty of baskets shaped from the shells of armadillos,” and they scrutinized 1,768 individual animals for band abnormalities from “a large stock of basket-shells in the hands of various dealers.”47

Newman and Patterson also demonstrated the existence of specific polyembryony: that all sets of embryos were the product of the division of a single fertilized egg. Subsequent researchers have built on such studies. Some people have become interested in the ability of the female “pocket battleship” to delay the development of the embryo for up to twenty months, making the armadillo’s gestation period almost as long as an elephant’s!48 Other researchers have concentrated on the scientific and especially the potential medical value of having identical quadruplet mammals to work with. Siblings are of the same sex and genetically identical; however, individuals may show variations in heart or spleen size, or differences in acids and other body chemicals—differences that are greater than one might expect. Unfortunately, it has proved extremely difficult to establish a program of sustained breeding in captivity so that researchers can easily produce and test sets of animals under controlled conditions.49

Frank Weaker, professor of anatomy at the University of Texas Health Science Center in San Antonio, has tried to get armadillos to breed in captivity. Weaker usually captured his own animals, but occasionally purchased them from a commercial supply house. One winter Weaker needed animals, so he ordered them from a dealer in Florida. The supplier told him that the shipment would be delayed for several weeks—until the hard weather in Texas improved, as his stock came from the Texas Hill Country. It seems that animal supply houses throughout the South still rely on part-time hunters to supply armadillos, which are then shipped to other parts of the country. Texas remains a major source region for captive stock.50

An important use of armadillos in medical research is in studies of leprosy. Leprosy, or Hansen’s Disease (HD) as it is officially called, is an infection whose cause was first discovered by Norwegian scientist Gerhard A. Hansen in 1873. The tiny bacilli (rod-shaped bacteria) of Mycobacterium leprae affect the skin, peripheral nerves, and sometimes the respiratory tract, eye, muscles, and reproductive organs. People dread leprosy because of the deformities associated with it. It develops slowly, and the reasons for its spread are largely unknown. Leprosy is considered the least infectious of the contagious diseases known to affect humans.

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