Department of Theriogenology, Faculty of Veterinary Medicine, Assiut University, Assiut, 71526, Egypt.
Department of Cells and Tissues, Faculty of Veterinary Medicine, Assiut University, Assiut, 71526, Egypt.
Sci Rep. 2022 Jul 29;12(1):13003. doi: 10.1038/s41598-022-17037-x.
Fertility in birds is dependent on their ability to store adequate populations of viable sperm for extended durations in sperm storage tubules (SSTs). The exact mechanisms by which sperm enter, reside, and egress from the SSTs are still controversial. Sharkasi chicken sperm showed a high tendency to agglutinate, forming motile thread-like bundles comprising many cells. Since it is difficult to observe sperm motility and behavior inside the opaque oviduct, we employed a microfluidic device with a microchannel cross-section resembling close to that of sperm glands allowing for the study of sperm agglutination and motility behavior. This study discusses how sperm bundles are formed, how they move, and what role they may have in extending sperm residency inside the SSTs. We investigated sperm velocity and rheotaxis behavior when a fluid flow was generated inside a microfluidic channel by hydrostatic pressure (flow velocity = 33 µm/s). Spermatozoa tended to swim against the flow (positive rheotaxis) and sperm bundles had significantly lower velocity compared to lonesome sperm. Sperm bundles were observed to swim in a spiral-like motion and to grow in length and thickness as more lonesome sperm are recruited. Sperm bundles were observed approaching and adhering to the sidewalls of the microfluidic channels to avoid being swept with fluid flow velocity > 33 µm/s. Scanning and transmission electron microscopy revealed that sperm bundles were supported by a copious dense substance. The findings show the distinct motility of Sharkasi chicken sperm, as well as sperm's capacity to agglutinate and form motile bundles, which provides a better understanding of long-term sperm storage in the SSTs.
鸟类的生育能力取决于其在精子储存管（SST）中储存足够数量的存活精子以延长时间的能力。精子进入、驻留和离开 SST 的确切机制仍存在争议。沙氏鸡精子有很高的聚集倾向，形成由许多细胞组成的游动线状束。由于很难观察到不透明的输卵管内的精子运动和行为，我们使用了一种微流控装置，其微通道横截面类似于类似于精囊的形状，允许研究精子聚集和运动行为。本研究讨论了精子束的形成方式、运动方式以及它们在延长 SST 内精子驻留时间方面可能发挥的作用。我们研究了在微流控通道内通过静水压力产生流体流动时精子速度和趋流行为（流速= 33 µm/s）。精子倾向于逆流游动（正趋流），并且与单独的精子相比，精子束的速度明显较低。观察到精子束以螺旋状运动游动，并随着更多单独精子的招募而在长度和厚度上增加。观察到精子束向微流控通道的侧壁靠近并附着，以避免被流速大于 33 µm/s 的流体冲走。扫描和透射电子显微镜显示，精子束由丰富的致密物质支撑。研究结果表明沙氏鸡精子具有独特的运动能力，以及精子聚集和形成游动束的能力，这有助于更好地理解 SST 中精子的长期储存。
