Evaluation of the Morphometry of Sperm from the Epididymides of Dogs Using Different Staining Methods

SIMPLE SUMMARY: Sperm morphometry is an important indicator of the quality of the spermatozoon and its effectiveness in fertilizing the egg. The morphological analysis of sperm collected from dog epididymis may be helpful in the diagnosis of reproductive disorders, valuable for breeding. There are no studies evaluating the morphometry of sperm in individual parts of the epididymal duct in dogs. For this reason, a study was carried out to evaluate the morphometry of sperm from the epididymides of dogs (caput, corpus, cauda) subjected to routine castration. This assessment was performed with the use of four staining methods (DiffQuick (DQ), SpermBlue (SB), eosin-nigrosin (EN) and eosin-gentian (EG)), popular in the assessment of sperm morphology and morphometry. The morphometric dimensions of sperm vary according to the segment of the epididymal duct, from which the cells are collected. Sperm taken from cauda of the epididymides had the smallest dimensions. These were sperm cells with smaller head dimensions (length, area, perimeter) and shorter length of the tail and the sperm total length than the sperm collected from corpus and caput. The study is especially important because it provides a more complete picture of the morphometry of sperm collected from the epididymides of dogs. Knowledge of the sperm morphometric dimensions can be helpful in developing semen preservation methods and assisted reproduction techniques. The combined use of multiple sperm staining techniques enables a more precise evaluation of male reproductive cells. These methods are appropriate for the evaluation of sperm structure, and the possibility of using all four methods enables a full characterization of sperm collected from the caput, corpus and cauda of the epididymides of dogs. ABSTRACT: Evaluation of sperm morphometry is an important criterion in the diagnosis of a male animal’s suitability for breeding. The aim of the study was to evaluate the morphometry of sperm from the epididymides of dogs subjected to routine castration using various staining methods. The study was carried out on semen collected from ten healthy dogs. Gonads were obtained from each dog during routine castration at a veterinary surgery. Then, the epididymides (caput, corpus, cauda) were isolated from the gonads, semen was collected from them and microscope slides were prepared. The slides for evaluation of sperm morphometry were prepared by four methods: DiffQuik, SpermBlue, eosin-nigrosin and eosin-gentian. A total of 2400 sperm were analyzed (240 sperm from the dog). The sperm collected from the caput and corpus of the epididymis were found to have larger heads and tails than those collected from the cauda of the epididymis. The staining method was shown to affect the morphometry of sperm taken from the epididymides of dogs. The staining methods differentiate the dimensions of the head of sperm in different parts of the epididymis but do not affect the length of the sperm tail. The occurrence of differences in the head dimensions of sperm may be linked to the use of different fixatives and chemical reagents in the staining procedure. Sperm stained by the EN method had the smallest head and tail dimensions. The greatest head area was noted in the sperm stained by the EG method. In the slides stained by the SB method, the sperm heads were relatively long but narrow. The methods used are suitable for the evaluation of sperm structure, and the possibility of using all four methods enables a full characterization of sperm collected from the caput, corpus and cauda of the epididymides of dogs.