Univ Estadual Paulista (UNESP), FMVA, Faculty of Veterinary Medicine, Department of Clinics, Surgery and Animal Reproduction, Araçatuba, Brazil.
Acta Vet Scand. 2012 Jan 12;54(1):1. doi: 10.1186/1751-0147-54-1.
Proximal cytoplasmic droplets (PCDs), a remnant of germ cell cytoplasm, are common non-specific morphological defects in bovine semen. This study evaluated the effect of higher percentages of PCDs on the quality of frozen-thawed bovine semen, embryo production and early embryo development.
Three ejaculates from each of five (group 1: PCD ≤ 1%, control) and eight adult Bos indicus bulls (group 2: PCD ≥ 24%) were analysed. Semen samples were examined for: post-thaw motility, vigour of movement, concentration, sperm morphology, slow thermoresistance test (STT), membrane integrity, acrosome status, mitochondrial function using fluorescent probes association (FITC-PSA, PI and JC-1) and sperm chromatin integrity using acridine orange assay. Two bulls from group 2, with 28.5% and 48.5% PCD, respectively, and three bulls from the control group, each with 0% PCD, were selected for IVF (in vitro fertilisation).
Semen analyses revealed a significant correlation (P < 0.01) between increased rates of PCD and sperm quality traits. Nevertheless, no differences were observed in sperm motility and vigour either before or after the STT or in the percentage of intact acrosomes (analysed by differential interference contrast microscopy (DIC) after STT), but membrane integrity, acrosome status (evaluated with FITC-PSA staining method after thawing) and mitochondrial function were reduced, when compared with group 1 (P < 0.05). The higher incidence of PCD was positively correlated to chromatin damage, especially after three hours of incubation at 37°C. IVF showed similar results for bull C2 (group 1, control) and bull P2 (group 2, group with higher PCDs).
Higher PCD levels influenced spermatozoa quality traits. IVF and embryo development data showed that cleavage, blastocyst formation and blastocyst hatching may have been influenced by the interaction of morphology traits and individual bull effects.
近端胞质滴（PCD）是精细胞胞质的残余物，是牛精液中常见的非特异性形态缺陷。本研究评估了较高百分比的 PCD 对冷冻解冻牛精液质量、胚胎生产和早期胚胎发育的影响。
从五头（第 1 组：PCD≤1%，对照组）和八头成年印度野牛公牛（第 2 组：PCD≥24%）的每头公牛的三个精液样本中进行分析。精液样本进行了以下检查：解冻后活力、运动活力、浓度、精子形态、缓慢热阻试验（STT）、膜完整性、顶体状态、使用荧光探针结合（FITC-PSA、PI 和 JC-1）评估线粒体功能和使用吖啶橙试验评估精子染色质完整性。从第 2 组中选择了两个公牛，其 PCD 分别为 28.5%和 48.5%，以及从对照组中选择了三个公牛，每个公牛的 PCD 均为 0%，用于体外受精（IVF）。
精液分析显示，PCD 率的增加与精子质量特征之间存在显著相关性（P<0.01）。然而，在 STT 前后或在完整顶体的百分比（用 STT 后的相差干涉对比显微镜（DIC）分析）方面，精子活力和活力没有差异，但膜完整性、顶体状态（用解冻后的 FITC-PSA 染色方法评估）和线粒体功能降低，与第 1 组相比（P<0.05）。更高的 PCD 发生率与染色质损伤呈正相关，特别是在 37°C 孵育 3 小时后。IVF 对公牛 C2（第 1 组，对照组）和公牛 P2（第 2 组，PCD 较高组）的结果相似。
更高的 PCD 水平影响精子质量特征。IVF 和胚胎发育数据表明，卵裂、囊胚形成和囊胚孵化可能受到形态特征和个体公牛效应相互作用的影响。
