Objectives

This study aimed to investigate the localization of cat spermatozoa and the site of sperm reservoir in the female genital tract at 30 min following natural mating.

Materials & Methods

Six cats were induced oestrus using 100 iu eCG im and allowed to mate once by the same male on day 3 of oestrus. The genital tract was removed at 30 min after mating and excised into 7 segments. The lumen of one side of each segment was flushed with 0.5 ml PBS, fixed in formalin and processed for routine histology. The contralateral side was fixed without prior flushing and processed for histology. The vagina was flushed after surgery. The sperm number in the vagina and each segment was evaluated. The genital segment was randomly selected from 3 out of 6 cats for histological examination for the sperm number in 20 of 5-µm sections for each segment.

Results

The mean total sperm number recovered by flushing was 4.5x10⁴, which were distributed throughout the female genital tract as follows: vagina, 75.7%; uterine body, 3.8%; caudal uterine horn, 5.7%; cranial uterine horn, 11.8%; uterotubal junction (UTJ), 1.6%; isthmus, 0.2%; ampulla, 0.1% and infundibulum, 1%. The histological finding showed the highest sperm number localized in the epithelial crypts of the UTJ. No significant difference of sperm number was found between flushed and non-flushed tissue sections (p<0.05).

Conclusion

At 30 min after mating, the majority of spermatozoa were found in the vagina in the cat. The sperm reservoir was established in the UTJ already at 30 min after mating. Only a few spermatozoa in the lumen were flushed while the majority was entrapped in the epithelial crypts.