Asymmetrical size and functionality of the pampas deer (Ozotoceros bezoarticus) testes: Right testis is bigger but left testis is more efficient in spermatogenesis

Abstract

Information about gonadal asymmetries in ruminants is very scarce. In this work, we performed three complementary studies to compare characteristics of both testes: (i) weight and size of offspring and adult dead males; (ii) the tissue:fluid relationship determined by ultrasound scanning; and (iii) the spermatogenic status using fine needle aspiration cytology. The right testis was heavier than the left one in both offspring and adult animals and had greater width and volume in adult males than the left one. The ultrasound pixel intensity was similar in both testes. The right testis tended to have more spermatogonia (p = .06) and had a greater percentage of early spermatids (p = .004) than the left testis. On the other hand, the left testis had a greater percentage of spermatozoa (p = .05). The left testis had a greater spermatozoa/spermatogonia ratio (p = .02) and tended to have more spermatozoa/Sertoli cells ratio (p = .07). The spermatogenic index tended to be greater in the left than in the right testis (p = .06). Overall, we concluded that the right testis of pampas deer males is bigger but according to the cytology, it seems to be less spermatogenically effective than the left one, but these differences are not explained by different tissue:fluid ratio in each testis. Although differences were greater in adults than in offspring, asymmetry was observed even in just born offspring.

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn

“…Testicular volume was the sum of the volume of both testicles, which was calculated assuming an ellipsoid shape [(4/3) π.(lenght/2).(width/2). (depth/2)] (Pérez et al, 2013;Ungerfeld et al, 2017). Also, the gonado-somatic index (GSI: testicular volume/body weight, cm 3 /kg) was calculated.…”

Macroscopic Anatomy of the Stifle Joint in the Pampa’s Deer (Ozotoceros bezoarticus-Linnaeus, 1758)

“…Most anatomical studies related to pampas deer have focused on their reproductive organs [9][10][11][12], digestive system [13][14][15], and cardiovascular system [16][17][18][19][20]. There are still many organs to be investigated, especially in the locomotor apparatus, where there is an absence of descriptions.…”

Testicular Morphological and Ultrasonographic Characterization of Male Gray Brocket Deers (Mazama gouazoubira) in Different Reproductive Status

“…Although Mazama gouazoubira is globally classified as of "least concern" by the International Union for Conservation of Nature, its populations are decreasing due to the extension of human communities [10]. Assisted reproduction programs are important tools for species conservation [36], thus improved diagnostic techniques may help with male selection, increasing conservation programs efficiency [46].…”

“…Also, the Doppler technique detected blood flow changes in testicular artery in different seasons [27], and in males with fertility disorders [29,34]. Yet, few studies have investigated male deer reproductive system [23,46].…”