Quality of canine spermatozoa retrieved by percutaneous epididymal sperm aspiration

A comparative study of canine epididymal sperm collection techniques and cryopreservation

Introduction

An optimized collection method and freezing protocol for preservation of epididymal spermatozoa remains a topic of interest to many scientists. The current study focused on the collection and preservation of canine epididymal spermatozoa. During the process of collection of canine epididymal spermatozoa, blood content can occur, which may affect sperm cryopreservation in a negative way. Here, we compared first two epididymal sperm collection techniques [epididymal mincing (EM) and single incision epididymal sperm aspiration (SESA)]; and next we tried to solve the issue of blood content using an erythrocyte lysis buffer (ELB).

Methods

Hence spermatozoa were collected after weighing the epididymides, either by EM or SESA, and sperm quality assessed prior to and post freezing (concentration, total sperm output (TSO), motility, viability and morphology). Next, new sperm samples were collected from eight epididymides by EM and subjected either to a standard freezing protocol or to an ELB treatment freezing protocol. Post-thaw sperm parameters (concentration, TSO, motility, viability and morphology), including intracellular reactive oxygen species (ROS) and lipid peroxidation were assessed. The correlation between the weight of the epididymis and the TSO was evaluated based on the collection technique, and differences in sperm parameters were detected both within different collection techniques and between different pre-freezing treatment protocols.

Results

There was a very strong correlation between the weight of the epididymis and the TSO for the EM technique (p  =  0.002, R2 =  0.6), along with an increased sperm motility with EM compared to SESA (median 80%, inter-quartile range (IQR) 88-65 and median 67.5%, IQR 72.5-52.5, respectively; (p  =  0.002). Post-thaw samples subjected to ELB treatment freezing protocol had lower motility and higher intracellular ROS compared to the standard freezing protocol (motility: median 56.25%, IQR 60-48.75 and median 70%, IQR 72.5-63, respectively; p   =  0.01; ROS: median 78.5%, IQR 81.25-75.5 and median 70%, IQR 70.5-68.75, respectively; (p  =  0.04).

Discussion

The results indicated that EM is a better technique to harvest epididymal spermatozoa despite the presence of some blood content. Furthermore, the ELB treatment should not be implemented to remove those red blood cells prior to cryopreservation of epididymal spermatozoa in dogs.

Influence of the Addition of Zinc Oxide Nanoparticles to Cryopreservation Medium for Dog Epididymal Spermatozoa

The purpose of this study was to assess the effect of different concentrations of zinc oxide nanoparticles (ZnONPs) introduced to an extender for frozen-thawed epididymal dog spermatozoa. Epididymides from 22 castrated dogs were minced and cultured in a Tris buffer. The recovered spermatozoa were diluted in Tris-Citric acid-Fructose (TCF) extender with different concentrations of ZnONPs (100 and 200 µg/mL) and control (0.0 µg/mL). Diluted samples were equilibrated at 5 °C for 2 hours before being packed in 0.25 mL straws and stored in liquid nitrogen (-196 °C). After thawing at 37°C for 30 seconds, sperm motility, viability, membrane integrity, acrosome integrity, DNA integrity, and lipid peroxidation by malondialdehyde (MDA) concentration were all measured. The results were presented as mean ± SEM. Adding 100 and 200 µg/mL ZnONPs to the cryopreservation medium significantly (P < .05) improved motility and membrane integrity compared to the control. Viability and acrosome integrity were considerably (P < .05) better at 100 µg/mL ZnONPs than at 200 µg/mL ZnONPs and the control. MDA concentration was significantly (P < .05) decreased at 100 µg/mL ZnONPs compared to 200 µg/mL ZnONPs and the control. When 100 µg/mL ZnONPs were compared to 200 µg/mL ZnONPs and the control, the percentage of DNA damage was significantly (P < .05) reduced. Consequently, adding 100 µg/mL ZnONPs to TCF extender resulted in a significant increase in the proportion of motility, viability, membrane-intact, and acrosome-intact dog epididymal sperm, as well as the preservation of DNA integrity and the prevention of lipid peroxidation at the membrane level.

The effects of epididymal sperm recovery methods on fresh and frozen-thawed sperm characteristics in dogs

The cauda epididymis holds a collectible source of fertile spermatozoa in cases of obstructive azoospermia, sudden death, and after elective or emergency castration. The current study was conducted to compare three different epidydimal sperm collection methods (Percutaneous epididymal sperm aspiration (PESA), microsurgical epididymal sperm aspiration (MESA), and retrograde epididymal wash (EW)) in the dog. Fifteen large-breed adult dogs were applied for comparing the PESA (left testicles) with MESA (right testicles) techniques, while five dogs were used for evaluation of MESA (left testicles) versus EW (right testicles). The recovered sperm cells from MESA and EW were subjected to cryopreservation. Total sperm recovery, level of blood contamination, and sperm quality markers (viability, morphology, plasma and acrosome membrane integrity, DNA fragmentation, and metabolic activity) were evaluated for fresh and frozen-thawed spermatozoa. We showed that the collection of epididymal sperm cells through the PESA method resulted in lower total sperm recovery and significantly reduced fresh sperm kinematic and quality measures. While, both MESA and EW procedures resulted in a high number of intact epididymal spermatozoa with appropriate cryo-tolerance potential. In conclusion, EW and MESA methods provide high-quality epidydimal spermatozoa with high cryopreservation potential in domestic dogs.

Canine and Feline Epididymal Semen-A Plentiful Source of Gametes

Simple Summary

The epididymis is a source of fertile spermatozoa. For some males, preserving spermatozoa that are stored in the epididymis might be an ultimate attempt for gamete preservation. The quality of epididymal semen is different from ejaculated semen in various animal species. Although assisted reproductive technologies (ART) have been introduced in cats as a tool to preserve valuable genetics of endangered wild felids, epididymal semen cryopreservation is still suboptimal in dogs. Therefore, in this paper, we carried out a review to list the morphological changes of spermatozoa during epididymal transit alongside with the potential that holds in the epididymal semen in dogs and cats. We believe that better comprehension of epididymal semen collection method, quality and freezability may aid in optimizing cryopreservation and enhance different applications of ART.

Abstract

Canine and feline epididymal semen provide an additional source of gametes to preserve the genetics of valuable breeding dogs and tomcats, especially for those that fail to ejaculate, need castration as a therapy or die unexpectedly. Moreover, since it is quite common to perform castration of non-breeding dogs and cats, the development of a gene bank of epididymal semen collected after castration would greatly contribute to increase the genetic diversity in dogs and cats. Collection and cryopreservation of epididymal semen necessitates a full understanding of the function of the epididymis and of the characteristics of epididymal spermatozoa as opposed to ejaculated semen. During collection of epididymal semen, specific factors may have a negative effect on epididymal semen quality and freezability. Accordingly, the elimination of these triggers could enhance epididymal semen freezability and consequently positively influence post-thaw semen quality and outcome for different ARTs.

Urethral catheterization after pharmacological induction for semen collection in dog

The α-adrenergic agents are known to influence erection and ejaculation, and ejaculatory reflex is a primarily α-adrenergically mediated event. This paper aims to describe the urethral catheterization technique after pharmacological induction for semen collection in domestic dogs. For dose determination, semen collection was performed using increasing doses of dexmedetomidine (5 μg/kg, n = 2; 10 μg/kg, n = 2 and 15 μg/kg, n = 2) associated to 3 mg/kg ketamine in six animals. Once the dose was established, additional semen collection using association of 15 μg/kg dexmedetomidine and 3 mg/kg ketamine was carried out in eight dogs. After the procedure, sperm volume (0.092 ± 0.03 mL), total motility (58.33 ± 8.7%), vigor (1.89 ± 0.309), sperm concentration (1186.67 ± 304.667 × 10⁶ sperm/mL), sperm plasma membrane integrity (83.22 ± 4.82%), acrosomal integrity (73 ± 6.187%) and normal sperm morphology (53.22 ± 5.6%) were assessed. Thus, this study demonstrates that urethral catheterization after pharmacological ejaculation using dexmedetomidine-ketamine association can be performed in dogs and it may be possible to obtain good semen quality, despite urine contamination.

Canine spermatozoa-What do we know about their morphology and physiology? An overview

Spermatozoa are unique cells because of their morphological and physiological characteristics. They are produced during the process called spermatogenesis. Spermatogenesis consists of three phases: spermatocytogenesis, spermiogenesis and spermiation, during which spermatozoa undergo several changes. Spermatogenesis takes place within the seminiferous tubules containing two types of cells-the germ cells and the Sertoli cells-that alongside the Leydig cells, which play an important role when it comes to normal fertility. Everything is regulated by the hypothalamic-pituitary-gonadal axis and specific hormones due to multi-hormonal feedback systems. Spermatozoa possess morphological and physiological features, which are sometimes completely different from what is observed in various somatic cells. What is more, canine spermatozoa have specific characteristics making them special compared to the spermatozoa of other mammalian species. The metabolic energy production, which is crucial for the appropriate functioning of spermatozoa, can be fuelled by different metabolic pathways utilizing different chemical substrates. Inseparable from the oxidative phosphorylation process is the production of reactive oxygen species, which are both essential and toxic to spermatozoa. Furthermore, epididymis is a very important structure, responsible for the transport and maturation of spermatozoa, which are then stored in the last segment of epididymis-the epididymal cauda. Moreover, the retrieval of spermatozoa from the epididymides is crucial for the development of assisted reproduction techniques and sperm cryopreservation methods. The information gained from the research on domestic dogs might be transferred to their wild relatives, especially those species categorized as endangered.

Localization of MIF-II on mammalian spermatozoa: A study revealing its structure, function and motility inhibitory pathway

Motility of spermatozoa is a crucial factor for determining semen quality. Here we report motility inhibitory factor (MIF-II) from goat epididymal plasma, revealing its structure, function, localization and motility inhibitory pathway. Structural characterization with MALDI revealed novelty of this protein while circular dichroism data confirmed its alpha helical nature. Higher dilutions of MIF-II antibody increased cauda sperm motility and induced immature/immotile caput sperm motility as tested microscopically. Higher number of sperm cells and lower dilutions of antibody induced agglutination in cauda sperm showing surface localization. Indirect immuno-fluorescence showed MIF-II localization throughout the caput sperm surface which relocated more towards acrosomal region with maturation. ELISA assay revealed gradual increase and decrease in concentration of MIF-II in epididymal plasma and plasma membrane respectively from caput to cauda. Signaling cascade that leads to sperm motility inhibition elevates nitric oxide levels through cAMP dependent pathway. MIF-II treatment doesn't alter sperm surface morphology. Expression pattern of MIF-II during epididymal maturation goes hand-in-hand with gaining motility potential as well as dormancy of spermatozoa before ejaculation. Both MIF-II and its antibody inhibit fertilization in-vitro thus expected to open new gateway for future male infertility and contraceptive development research.

Canine epididymal spermatozoa: A hidden treasure with great potential

The hidden treasure represented by epididymal spermatozoa has great potential in the current reproductive technologies in dogs. In case of azoospermia or when a donor male accidentally dies or undergoes orchiectomy, the retrieval of epididymal spermatozoa opens new possibilities to generate progeny. Spermatozoa can be collected by different techniques from ex vivo or in vivo testicles and can be cryopreserved for a future use. Freeze tolerance of canine epididymal spermatozoa seems lower than that of ejaculated spermatozoa; however, puppies were born after artificial insemination with frozen epididymal semen, other than with fresh and chilled. Even though several aspects need to be further investigated, advances have been recently made in the use of epididymal spermatozoa in assisted reproduction in dogs.

Cryopreservation of canine epididymal sperm using ACP-106c and TRIS

The objective was to cryopreserve sperm recovered from the canine epididymal cauda immediately after an orchiectomy. The sperm was stored for 12h at 4 °C using ACP-106c and TRIS as extenders. Sixty adult male dogs were used. The testis-epididymis complex (TEC) was removed, immersed in 0.9% saline and transported to the laboratory. The 60 TEC were divided into groups according to the 4 °C cooling time (0 h or 12 h) and according to the extender used for sperm recovery (ACP-106c or TRIS), forming 4 experimental groups: G0h-ACP, G12h-ACP, G0h-TRIS and G12h-TRIS. The sperm were recovered from the epididymal cauda using the retrograde flow technique. Next, 1.0 mL of ACP-106c or 1.0 mL of TRIS (preheated to 37 °C for 5 min) was added to the sperm of each epididymis. One week later, the sperm was thawed at 37 °C for 1 min, and its morphology, functionality and total and progressive sperm motilities were analyzed. Other parameters were obtained by Computer Assisted Semen Analysis (CASA). The data were submitted to multivariate analysis of variance (MANOVA) (P<0.05). The total motility values were 52.17 ± 1.78 and 49.8 ± 1.93 for groups G0h-ACP and G12h-ACP and 50.7 ± 2.06 and 43.90 ± 2.51 for groups G0h-TRIS and G12h-TRIS, respectively. A decrease in total sperm motility was observed after 12h of cooling for both extenders (P<0.05). ACP-106c can be used as an extender for freezing canine epididymal sperm, and the freezing procedure must be performed immediately after sperm recovery.