Morphology, morphometry, ultrastructure, and mitochondrial activity of jaguar (Panthera onca) sperm.

The jaguar is categorized as "Near Threatened". Conservation strategies, therefore, are needed which include use of reproductive biotechniques. For implementation of biotechnique use, the reproductive characteristics of the species must be understood, which is currently not the case. This study, therefore, aimed to describe the detailed morphology of jaguar sperm, and to evaluate the sperm mitochondrial activity. Five male adults were used. Slides stained with Rose Bengal were used for morphometric and morphological analyses. The length and the width of the sperm head were measured, as well as the length of the middle piece, the tail, and the total length. Scanning and transmission electron microscopy were used for ultrastructural analysis. Mitochondrial function was assessed using the marker 3,3'-diaminobenzidine (DAB). The results are expressed as means ± SEM. The most significant morphological abnormalities observed were head (9 ± 1.7%) and tail defects (12.5 ± 3.3%). The width and length of the head were 3.6 ± 0.03 μm and 4.9 ± 0.02 μm, respectively. The middle piece measured 9.7 ± 0.3 μm, the tail measured 54.5 ± 4.4 μm, and the total length of the sperm was 59.5 ± 0.1 μm. Electron-lucent regions and approximately 54 mitochondrial spirals in the middle piece were identified in the nucleus using electron microscopy. The greatest percentages of cells were classified as DAB I (46.6 ± 4.9%) and DAB II (38 ± 4.4%). The data provide detailed information on the sperm characteristics of jaguars and can support research on germplasm conservation for the species.