Influence of selected extenders for liquid storage at 4ºC of breeding chinchilla (Chinchilla lanigera) semen on sperm DNA integrity. Folia Biologica (Kraków) 63: 279-287. The influence of two commercial and two laboratory oriented extenders on survival rate and DNA integrity of chinchilla (Chinchilla lanigera) sperm was determined during liquid storage. Semen was collected using an electroejaculator from 6 adult male chinchillas. Ejaculates (n=16) were diluted with extenders to obtain a concentration of 40×10 ! sperm/5 µl. After dilution the semen samples were stored at 4ºC. The percent motility, progressive motility, and morphology were assessed conventionally, whereas DNA integrity was evaluated by Single Cell Gel Electrophoresis (comet) assay at 0 (just after dilution), 24, 48 and 72 h. Conventional assessment of sperm quality showed that commercial extenders are characterized by the lowest sperm survival parameters out of the investigated extenders. In commercial extenders spermatozoa lost their capacity for progressive motility compared to laboratory extenders. After 24 h storage, from 21.67% to 30% of motile sperms were observed in commercial extender whereas total sperm motility was 63.33% (41.67% with progressive motility) in samples in which stallion semen extender was used. After 72 h storage, 10% of sperm were motile in stallion semen extender while no sperm movement was observed in tubes containing the commercial extender. Furthermore, a lower percentage of damaged spermatozoa in laboratory oriented extenders was demonstrated. It was also stated that along with the extended time of semen storage at 4ºC, commercial extenders lost their protective action. An analysis of DNA content in the heads of sperm cells and tail moment (TM) showed that the most useful extender for liquid preservation of chinchilla semen was the extender for stallions.

There is relatively little information about the karyotype structure of the chinchilla (Chinchilla lanigera Mol.), an endemic South American rodent with 2n = 64 chromosomes and "duplicate-type X chromosome". The species, endangered in nature, is a popular domesticated animal providing one of the most valuable furs in the world. In the present study, detailed karyotype analysis of the domestic chinchilla was performed using selected methods of differential chromosome staining (G-banding, C-banding, C-banding/DAPI, CMA 3 /DA/DAPI, Ag-NOR staining) as well as fluorescence in situ hybridization (FISH) with rDNA and telomeric (TTAGGG) n repetitive probes. The analysed specimens showed 59 metacentric and five submetacentric chromosomes. C-banding revealed mainly centromeric distribution of heterochromatin on the autosomes, interstitial and centromeric C-positive bands on the X chromosome and almost entirely heterochromatic nature of the Y chromosome. The average amount of heterochromatin in the haploid autosome set (31A) was 11.44%, whereas in the X chromosome 39.84%. Two active nucleolar organizer regions (NORs) and 45S rDNA repeats were located within one pair of big autosomes. In respect of morphology and G-banding patterns, the chinchilla chromosomes were arranged in homologous pairs and a G-banded karyotype was proposed. The obtained results could be the first step towards determination of the standard karyotype for the breeding chinchilla.

Sperm cells isolated from the tail of the epididymis and from the semen of the same individuals were analysed. The use of silver nitrate to stain sperm cells isolated from the tail of the epididymis made it possible to identify structures that were not visible in the sperm from semen. Silver nitrate very clearly distinguished the acrosomal and distal parts of the sperm head. Following silver nitrate staining, the sperm isolated from the tail of the epididymis were characterized by dark ‘collars’ in the distal part of the head. These ‘collars’ are not visible in the sperm cells isolated from semen. The results of the study indicate differences in the dimensions of sperm isolated from the tail of the epididymis and sperm in semen. Sperm isolated from the tail of the epididymis had smaller heads, despite their longer length, and had longer midpieces and tails than ejaculate sperm. Silver nitrate staining is a simple and fast technique. Silver nitrate makes it possible to identify the acrosome and post‐acrosomal region of the sperm head and to clearly identify the midpiece. Therefore, it can be successfully used to supplement routine techniques for evaluating sperm morphology or as an independent technique.

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Contents Sperm morphology and morphometry are considered parameters in fertility diagnosis. They are especially important in the case of species for which there is no standard with respect to morphometric sperm parameters. It is then crucial to apply the staining technique that has the least influence on the sperm structure and provides the most detailed image, so as to enable measurements. The aim of the research was to assess the morphometric parameters of rabbit sperm using silver nitrate staining. The staining process revealed a detailed image of the spermatozoon head and tail, thus enabling precise measurements. From these basic morphometric parameters, four additional shape indices characterizing the sperm head were calculated: ellipticity, elongation, roughness and regularity. These parameters more precisely characterize the shape of the sperm head. Silver nitrate staining can be used as an independent technique in assessment of sperm structure or to supplement routine diagnostics.