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  3. Two techniques have recently been developed to simplify research and reduce the number of nonhuman primates needed in studies of

Two techniques have recently been developed to simplify research and reduce the number of nonhuman primates needed in studies of

admin2010-05-14  66
问题    Two techniques have recently been developed to simplify research and reduce the number of nonhuman primates needed in studies of certain complex hormonal reactions. One technique involves the culturing of primate pituitary(垂体)cells and the cells of certain human tumors. In the other, animal oviduct (输卵管) tissue is transplanted under the skin of laboratory primates. Both culturing techniques complement existing methods of studying intact(完整的) animals.
   With an in vitro culturing technique, researchers are deciphering how biochemical agents regulate the secretion of prolactin(催乳激素), the pituitary hormone that promotes milk production. The cultured cells survive for as long as a month, and they do not require serum (血清), a commonly used culture ingredient that can influence cellular function and confound study results. One primate pituitary gland may yield enough cells for as many as 72 culture dishes, which otherwise would require as many animals.
   The other technique allows scientists to monitor cellular differentiation in the reproductive tracts of female monkeys.  While falling short of the long-sought goal of developing an in vitro model of the female reproductive system, the next-best alternative was achieved. The method involves transplanting oviduct tissue to an easily accessible site under the skin, where the grafted cells behave exactly as if they were in their normal environment. In about 80 percent of the grafts, blood vessels in surrounding abdominal skin grow into and begin nourishing the oviduct tissue. Otherwise, the tissue is largely isolated, walled off by the surrounding skin. A cyst(囊胞) forms that shrinks and swells in tandem(一前一后的串联) with stages of the menstrual cycle. With about 80 percent of the grafts reestablishing themselves in the new site, a single monkey may bear as many as 20 miniature oviducts that are easily accessible for study.  Because samples are removed with a simple procedure requiring only local anesthesia, scientists can track changes in oviduct cells over short intervals. In contrast, repeated analysis of cellular changes within the oviduct itself would require abdominal surgery every time a sample was taken a procedure that the animals could not tolerate.
   Scientists are using the grafting technique to study Chlamydia (衣原体)infections, a leading cause of infertility among women. By infecting oviduct tissues transplanted into the abdominal skin of rhesus (罗猴)monkeys, researchers hope to determine how the bacteria cause pelvic inflammatory disease and lesions(损害)that obstruct the oviduct. Such research could eventually lead to the development of antibodies to the infectious agent and a strategy for producing a Chlamydia vaccine.
According to the passage, Chlamydia causes infertility in women by ______.
选项 A、causing tissue changes which block the oviduct
B、shrinking and swelling tissues in conjunction with the menstrual cycle
C、allowing skin tissue to encyst reproductive tissue
D、necessitating abdominal surgery to remove damaged tissue
答案A
解析 这也是一道细节题。文中的最后一段论述了题目的内容，这里作者讲了the infection causes lesions which obstruct the oviduct。这在A选项中得到了很好的总结。B与C都是错的。它们的内容在文中是提到了，但它们都是答非所问。它们讲到了如何进行研究却没有提及妇女患不育症的原因。D可能是仅次于A的最好答案。它讲到了tissue damage，但文中并没有谈及切除损害组织手术的必要性。或许我们可以推想这是一种合适的医疗手段，但这种手段并未在文中特别提及。
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