Use of a Modified Rotating Cutting Needle for Testicular Biopsy in Cynomolgus Monkeys (Macaca fascicularis)

Testicular biopsy is an important and widely used approach in studies and clinical research. Testicular needle biopsy has been increasingly used to replace traditional open biopsy in recent years. In 1995, a modified rotating cutting needle was developed for testicular biopsy of infertile men. We report on the design of a modified rotating cutting needle and its use in testicular needle biopsies in cynomolgus monkeys (Macaca fascicularis) to establish its adequacy for use on these laboratory animals. The profile of the modified needle follows the original rotating cutting needle, but we have made 2 improvements: the outer diameter of the puncturing needle is now 50% larger (3.0-mm) to enable us to obtain adequate samples for research investigations, and the hub of each needle is extended for easy handling. The number of intact seminiferous tubules in a section obtained by use of the 3-mm modified needle from 10 cynomolgus monkeys was 52 ± 28 with a range of 27 to 118 in 10 samples. The quality of the samples was adequate for histopathologic interpretation. We also compared the sample quality obtained by use of modified needles of various diameters: 1.5, 2.0, and 3.0-mm. The 1.5-mm diameter modified needle did not allow us to obtain sufficient amounts of testicular tissue from the monkeys. Samples obtained by using the 2.0-mm diameter needle were adequate for histologic examination of seminiferous tubules, but interstitial tissues were not always preserved. In the large samples obtained by using the 3.0-mm diameter needle, the structures of seminiferous tubules and interstitial tissues were preserved. This study demonstrated that the 3.0-mm diameter modified rotating cutting needle is the best instrument for testicular needle biopsy in cynomolgus monkeys. It is useful for performing rapid, easy, less-invasive, reliable testicular biopsy when used on these laboratory animals.