Morphology, morphometry and chromatin distribution in llama sperm nuclei

The objectives of this study were as follows: (i) to describe and evaluate the frequencies of different morphologies of llama sperm nuclei, (ii) to determine morphometric values of nuclear parameters, (iii) to describe and estimate the frequencies of different classes of chromatin distribution and (iv) to measure haploid DNA content and analyse its nuclear distribution. The study was performed using ejaculates collected from seven males, and sperm nuclei were stained with the Feulgen reaction. Normal morphology ranged from 78.36% to 93.92%, and abnormalities included short, small, large, pyriform, narrow, micro and round nuclei. Important differences in nuclei considered normal were found between some males. The following average values were obtained for each sperm nuclear morphometric parameter analysed: area 11.64 μm² , perimeter 13.16 μm, length 5.12 μm, width 2.81 μm, ellipticity 1.85 and form 0.83. Differences between males were significant for all the parameters (p < .01). Light microscope observations and cytophotometric determinations allowed discriminating between three classes of chromatin distribution: homogeneous, diffuse and showing a clear band. Significant differences between males were found for the frequencies of the three classes (p < .01). Cluster analysis methods were used to estimate the resemblance between males according to the characteristics of their sperm nuclei. A great intermale variability was found for morphological, morphometric and chromatin distribution data. These parameters would have low dependence between them.