Andraszek, K. and Smalec, E. 2011. The use of silver nitrate for the identification of spermatozoon structure in selected mammals. Can. J. Anim. Sci. 91: 239Á246. The spermatozoon is one of the most diversified cell types, and the chromatin of the haploid spermatozoon genome is essentially different from that of the somatic cell as regards its chemical composition, structure and function. Although the structure of spermatozoon chromatin has crucial importance for fertilization and embryo development, standard staining techniques are still predominantly used for identifying semen quality and the assessment of spermatozoa is most often limited to detecting irregularities in their morphological structure. The aim of the present research was to evaluate the usefulness of silver nitrate staining for assessing spermatozoon morphology and identifying spermatozoon structure. Spermatozoa isolated from testes and semen were examined. Silver nitrate staining made it possible to identify many significant details of the morphological structure of the spermatozoon and could be successfully employed in sperm morphology assessments.Key words: Spermatozoa, testicle, spermatogenesis Andraszek, K. et Smalec, E. 2011. Utilisation du nitrate d'argent pour e´tudier la structure des spermatozoı¨des chez certains mammife`res. Can. J. Anim. Sci. 91: 239Á246. Le spermatozoı¨de est l'une des cellules les plus diversifie´es qui soient et la chromatine du spermatozoı¨de haploı¨de diffe`re essentiellement de celle de la cellule somatique pour ce qui est de sa composition chimique, de sa structure et de sa fonction. Bien que la structure de la chromatine dans le spermatozoı¨de joue un roˆle capital dans la fe´condation et le de´veloppement de l'embryon, les techniques de coloration usuelles servent encore principalement a`identifier la qualite´du sperme et l'e´valuation des spermatozoı¨des se limite souvent a`la de´tection des anomalies morphologiques. Les chercheurs voulaient e´tablir l'utilite´de la coloration au nitrate d'argent pour e´tudier la morphologie et pre´ciser la structure des spermatozoı¨des. Ils ont examine´des spermatozoı¨des isole´s des testicules et du sperme. La coloration au nitrate d'argent permet d'identifier de nombreux de´tails morphologiques importants dans la structure des spermatozoı¨des et on pourrait s'en servir pour e´valuer la morphologie du sperme.

The SCE test is often used as a sensitive and reliable technique in the biomonitoring of genotoxicity of mutagenic and carcinogenic agents. This study analysed the frequency of sister chromatid exchange in domestic horse chromosomes depending on the habitat and age of the analysed horses. The chromosome preparations were obtained from an in vitro culture of peripheral blood lymphocytes stained using the FPG technique. Both the habitat and the age significantly influence SCE frequency. A higher SCE incidence was observed in horses that lived in a large urban agglomeration than in those from the country. Also, a higher SCE incidence was identified in the group of horses above 6 years of age in comparison with the younger ones. Additionally, the frequency of SCEs in the first, second and third chromosomes and the X sex chromosome were analysed in detail. More exposed to the effect of environmental pollutants, the horses from the urban environment developed more double and triple SCEs in comparison with the village horses. The urban horses also developed quadruple SCEs, in addition to the less frequent exchanges.

In studies of chromosome instability, the sister chromatid exchange (SCE) test is a particularly sensitive cytogenetic assay for detecting DNA damage. SCE tests of chromosome instability were performed in the group of 6 horse breeds (Pure-bred Arabian, Malapolski horse, Polish noble half-bred, Polish cold-blooded, Hucul and Polish Konik). The chromosome preparations were obtained from our in vitro culture of peripheral blood lymphocytes stained using the FPG technique. The mean number of SCEs/cell in the analysed population of horses was 5.14±1.44. The mean frequency of SCEs in the 6 analysed horse breeds varied depending on the breed. Statistically significant differences were observed between the horse breeds (P<0.01).No statistically significant differences in the number of SCEs per cell were found between the males and females (5.10±1.34 and 5.20±1.52, respectively). The horses were also assessed for the number of SCEs/cell in relation to the age of the animals. The differences between the age groups were statistically significant (P<0.01).

Abstract. The Polish White Improved goat karyotype consists of 29 pairs of acrocentric autosomes, a large acrocentric X chromosome and a metacentric Y chromosome which is the smallest in the karyotype. Staining of chromosomes with AgNO,sub>3 solution has revealed active nucleolar organizer regions (NOR) in terminal parts of q arms of pair 2, 3, 4, 5, and 28 chromosomes. Out of the total of 100 analysed cells 736 active NORs have been found, on average 7.4±0.2 per cell. Active NORs were most frequently observed in pair 2, and 3 chromosomes, most rarely on pair 5 chromosomes. In all the analysed cells 141, satellite associations (SA) were observed, on average 1.4±0.2 per cell. SAs most often occurred in cells with seven active NORs, and least often in cells with three or four nucleolar organizer regions. Most frequently in SAs the presence of pair 2, 3 and 28 chromosomes was observed. On meiotic chromosomes staining with AgNO3 solution revealed two nucleoli stained with different intensity. Both nucleoli in the cell were of similar size.

Cytogenetic tests are highly reliable, sensitive indicators of the early effects of genomic instability. Their results provide information on the organism’s susceptibility to exogenous and endogenous factors and are measures of the degree of repair of DNA damage. Our study assessed spontaneously occurring damage in following four breeds of sheep: Polish Heath, Polish Lowland (Zelazna variety), Polish Blackhead, and Berrichon du Cher. Instability was identified using the following three different tests: a sister chromatid exchange (SCE) assay, identification of fragile sites, and the comet assay. The distribution of instabilities varied depending on the breed. The mean frequency of SCEs was 5.13 ± 1.58, whereas that of fragile sites was 3.30 ± 1.24. The mean level of DNA damage (% head DNA) was 96.52 ± 6.59. The most damage to genetic material was observed in the Berrichon du Cher sheep, and the least in the Polish Heath sheep. The tests used are reliable biomarkers of genome stability in animal breeds, as well as in individuals within breeds.