Use of computerized image analysis in the morphometric characterization of giant panda (Ailuropoda melanoleuca) spermatozoa obtained from the epididymis 4 hours postmortem

Abstract

AbstractThe reproductive tract of Chu‐Lin, a giant panda that had died at Madrid Zoo, was removed. Four hours postmortem the epididymides was cut with a blade, and the spermatozoa were collected and immersed in a freezing medium. The sample was kept under refrigeration at 5°C. After 4 hr the sperm suspension was aspirated into 0.25‐mL straws, which were held for 7 min in nitrogen vapors before they were plunged into liquid nitrogen. To characterize sperm population and distribution, a morphometric study of the triple‐stained smears of the thawed semen sample was undertaken with the aid of computerized image analysis. Spermatozoa with intact acrosomes were selected and assessed using an immersion lens (1,000×) and bright‐field illumination. The software made it possible to take six basic linear measurements of each spermatozoon: maximum head width (HW), base of the head (BH), maximum head length (HL), midpiece length (ML), midpiece width (MW), and terminal piece length (TL). The system was connected to a data base from which derived parameters could be calculated: head form factor (HL/HW), total flagellum length (TFL), total sperm length (TSL), and the proportion of each of the sections in relation to the whole. The results of the morphometric study did not demonstrate the existence of sperm subpopulations, as the measurements of the 100 spermatozoa analyzed were relatively homogeneous with regard to their distribution for each of the parameters considered. The sperm head of the giant panda displayed a relatively rounded morphology, and the HL/HW was 1.24±0.03. Mean head length was 5.05±0.08 µ, and mean head width was 4.07±0.08 µ. The mean total length of the giant panda spermatozoon was 49.26±0.67 µ. Zoo Biol 22:355–364, 2003. © 2003 Wiley‐Liss, Inc.