Animal Reproduction (AR)
Animal Reproduction (AR)
Original Article

Head morphometry and chromatin instability in normal boar spermatozoa and in spermatozoa with cytoplasmic droplets

Thais Schwarz Gaggini, Lays Oliveira Rocha, Elisson Terêncio Souza, Fernanda Marcondes de Rezende, Robson Carlos Antunes, Marcelo Emílio Beletti

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In boar studs, morphological analyses are used to evaluate sperm quality and thereby categorize ejaculates as either approved or rejected. Normally, morphological characteristics correlate with chromatin disorders, but studies to date have only considered the average of abnormalities; cells were not segregated as normal or abnormal. The aim of this study was to assess whether the presence of cytoplasmic droplets was associated with morphometric characteristics and chromatin instability of spermatozoa heads. Morphological analyses were performed on semen from 11 boars using phase contrast microscopy (200 cells per sample). Normal cells were differentiated from those with cytoplasmic droplets and both types were evaluated separately. Photomicrographs were acquired of normal spermatozoa (Group NOR, N = 1,207) as well as spermatozoa with proximal and distal cytoplasmic droplets (Group DROP, N = 725). Sperm-head morphometry and chromatin structure were evaluated using the toluidine blue technique. Spermatozoa heads in the DROP group were longer (8.37 ± 0.60 × 8.31 ± 0.53; P = 0.025), narrower (4.16 ± 0.21 × 4.19 ± 0.19; P = 0.03), and more symmetric on the sides (0.973 ± 0.012 × 0.971 ± 0.011; P = 0.007) than were spermatozoa heads of the NOR group. The DROP group also had a greater average ellipticity (0.335 ± 0.034 × 0.329 ± 0.031; P = 0.0004), a greater percentage of decondensed chromatin (2.71 ± 3.87 × 2.28 ± 1.38; P < 0.0008), and a greater chromatin heterogeneity (4.66 ± 1.40 × 4.40 ± 1.42; P < 0.0001). A greater frequency of semen collection results in a shorter period of cell maturation and this probably affected the degree of chromatin condensation and the cytoplasmic droplet migration, with concomitant effect on the head morphometry measurements. In conclusion, compared with normal spermatozoa, those with cytoplasmic droplets show altered morphometric characteristics, such as longer and narrower spermatozoa heads. They likewise have greater chromatin instability, resulting in a higher percentage of decondensed chromatin and more heterogeneous chromatin.


decondensed chromatin, cytoplasmic droplet, boar semen, morphology, morphometry.


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