Stereological Studies on the Testis of Adult Male African Giant Rat (Cricetomys gambianus, Waterhouse)

The science of Stereology deals with a body of methods for the exploration of three-dimensional space, when only two-dimensional sections through solid bodies or projections on a surface are available. It provides practical techniques (model- or design-based techniques) for extracting quantitative information about a three-dimensional material from measurements made on two-dimensional planar sections of the material. African giant rat (AGR) is in general appearance, much like an extremely large rat. The tail however, is distinctive; it is long and robust with the proximal portion dark, like the body of the animal, while the terminal part is white. Cheek pouches are present hence the animal is sometimes referred to as the pouched rat. However, there is dearth of information regarding the animal's testis, hence the purpose of this study was to obtain morphometric information on some parameters of its testis. In this study, the testicular volume and weight, total number of seminiferous tubules and numerical density of seminiferous tubules, as well as volume fraction of interstitium and volume fraction of testicular capillaries were investigated. The results showed that the mean body weight and testes weight of the adult AGR was 848.14g and 0.95g respectively, with no significant correlation ( p<0.05) between these parameters (r = 0.62). The mean weight observed for the left and right testes were very similar (p<0.05), with a significant correlation (r=0.99). Similarly, the mean volume for the right and left testes, were very similar (p<0.05) and a positive significant correlation was observed (r = 0.97). The mean numerical density of seminiferous tubules of the left and right testes was -9-3 -9-3 approximately 6.54 x 10 µm and 6.06 x 10 µm respectively with a significant correlation (p<0.05) between the left and right testes (r = 0.88). The mean of the total number of seminiferous tubules of the left and right testes was approximately 55 and 49 respectively, with no significant correlation (p> 0.05) observed between the left and right testes (r = 0.36). A negative correlation with no statistical significance (p> 0.05) was observed for the mean fraction of interstitium of the left and right testes (r = -0.31). The results also showed a significant correlation (p< 0.05) for the mean fraction of capillaries of the left and right testes (r = 0.64). This study provides baseline data that could be used for further research on the testis of the AGR.

Key Words: African giant rat (Cricetomys gambianus, Waterhouse); Stereology; Testis