Aspects of the Macroscopic Testicular and Epididymal Morphology in the Greater Rhea, Rhea Americana (Linneaus-1758) Birds

The purpose of this research was to study the macroscopic testicular and epididymal morphology of the greater rhea. The testicles of 54 greater rhea bred in captivity were utilized. The samples were collected November 2005 (n=14), December 2006 (n=20) and May 2007 (n=20). During commercial slaughter, the testicles and epididymides were collected and their following morphometric parameters were immediately measured: length, width, thickness, circumference, volume, weight of the parenchyma and the tunica albuginea, also aspects such as shape, cavity implantation, relationship with other organs and vascularization. The testicles presented cylindrical shape, with a thin, dense and transparent tunica albuginea, and the vascularization was accomplished by the testicular artery that ramifies from the cranial rectal artery. In the samples from December 2006 and May 2007, the media from the macroscopic measures of the right testicles were volume 58.7 and 14.7ml, length 9.87 and 3.5cm, width 2.4 and 0.6cm, thickness 2.4 and 0.5cm, circumference 8.0 and 2.3cm, parenchyma weight 27.6 and 6.1g and tunica albuginea weight 1.0 and 0.3g, P<0.05, respectively. The epididymides, the media from macroscopic measures December 2006 and May 2007 were volume 7.7 and 3.0ml, length 5.8 and 1.3cm, width 0.7 and 0.3cm, thickness 0.6 and 0.3cm, circumference 2.5 and 1.2cm, tissue weight 6.4 and 2.8g and capsule weight 0.4 and 0.1g, P<0.05, respectively. Some measures from the right testicle and epididymis were superior to measures taken from the left ones (P<0.05), but these were not characterizing asymmetry. The morphometric parameters observed during November 2005 remained on an intermediate situation (P<0.05); however, they were quantitatively closer to the means of December 2006, which may characterize it as a potential transition period between repose and sexual activity. Morphologically, the testicles and epididymides of greater rhea have common points with other researched birds; however, differences were observed. The testicles and epididymides of the Rhea americana are influenced by the environment, presenting reproductive activity season (November-December) during late spring, early summer and sexual repose season (May) during autumn-winter. The morphometric testicular and epididymal measurements were introduced. The morphometric parameters of testicles and epididymides exhibited differences between winter and spring-summer that could be established like sexual activity season.