Caracterización espermática de semen eyaculado por estimulación eléctrica del Tapir amazónico (Tapirus terrestris)

Abstract

The Amazonian Tapir (Tapirus terrestris), a threatened species in Ecuador, should be included in genetic resource management programs through the implementation of cryogenic banks. Hence, semen collection techniques, sperm quality and kinematics, and their cellular structure are primordial to the optimization of cryopreservation. The objective of this research was to characterize the sperm quality of the Amazonian Tapir as a base model for implementing a cryogenic bank. For this purpose, three semen ejaculates were collected from an 8-year-old Amazonian tapir of 250 kg housed in captivity conditions at the Yurak Allpa Zoo-Refuge. Firstly, the testicles and sexual glands were evaluated by ultrasound to verify their integrity before ejaculation. Subsequently, the range of electrical stimuli after transrectal ultrasound-guided massage of the accessory sex glands (TUMASG) to provoke ejaculation was evaluated. Sperm kinematics and morphometry, plasma and acrosomal membranes integrity, and morphological abnormalities were assessed using a CASA-SCA® system, PI/PNA-FITC double fluorescent test, and SpermBlue® stain, respectively. The results showed testicles and their epididymides and the bulbourethral glands and seminal vesicles showed normal echogenicity on ultrasonography. In addition, the TUMASG technique plus 14 ± 3 electrical stimuli (3 – 6 v) were necessary to provoke an electroejaculation, with previous sedation. Nevertheless, sperm quality was undesirable because only one of the three ejaculates produced minimal movement (total motility: 4.06%) and plasma and acrosomal membrane integrity (5%). The average morphological integrity was 68.1 ± 6.23%, presenting 17.7 ± 4.78% of distal cytoplasmic droplets. The average dimensions of the heads were: length: 6.6 ± 0.77 µm, width: 2.7 ± 0.27 µm, area: 17.6 ± 0.97 µm2 , and perimeter: 14.4 ± 0. 70 µm; and a mid-piece area of 12.7 ± 5.34 µm2 . In conclusion, the TUMASG technique plus electrical stimulation is adequate to obtain semen ejaculates of tapir with previous sedation however, the sperm quality of the donor male was undesirable and poor quality and is not recommended for cryopreservation. Finally, cell morphometry allowed us to know the dimensions of the head and mid-piece that will serve as a reference to continue with cryopreservation studies in this species.