Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany.
Research Training Group 2416 MultiSenses - MultiScales, RWTH Aachen University, Aachen, Germany.
Elife. 2021 Jan 27;10:e62885. doi: 10.7554/eLife.62885.
Spermatogenesis, the complex process of male germ cell proliferation, differentiation, and maturation, is the basis of male fertility. In the seminiferous tubules of the testes, spermatozoa are constantly generated from spermatogonial stem cells through a stereotyped sequence of mitotic and meiotic divisions. The basic physiological principles, however, that control both maturation and luminal transport of the still immotile spermatozoa within the seminiferous tubules remain poorly, if at all, defined. Here, we show that coordinated contractions of smooth muscle-like testicular peritubular cells provide the propulsive force for luminal sperm transport toward the rete testis. Using a mouse model for in vivo imaging, we describe and quantify spontaneous tubular contractions and show a causal relationship between peritubular Ca waves and peristaltic transport. Moreover, we identify P2 receptor-dependent purinergic signaling pathways as physiological triggers of tubular contractions both in vitro and in vivo. When challenged with extracellular ATP, transport of luminal content inside the seminiferous tubules displays stage-dependent directionality. We thus suggest that paracrine purinergic signaling coordinates peristaltic recurrent contractions of the mouse seminiferous tubules to propel immotile spermatozoa to the rete testis.
精子发生是男性生殖细胞增殖、分化和成熟的复杂过程,是男性生育能力的基础。在睾丸的生精小管中,精子通过有丝分裂和减数分裂的一系列定型分裂,由精原干细胞不断产生。然而,控制精子在生精小管内成熟和管腔运输的基本生理原理,如果有的话,也定义得很差。在这里,我们表明,平滑肌样的睾丸小管周围细胞的协调收缩为管腔精子向睾丸网的运输提供了推进力。使用体内成像的小鼠模型,我们描述并量化了自发的管状收缩,并显示了小管周围 Ca 波和蠕动运输之间的因果关系。此外,我们还确定了 P2 受体依赖性嘌呤能信号通路作为体外和体内管状收缩的生理触发因素。当受到细胞外 ATP 的挑战时,生精小管内管腔内容物的运输显示出与阶段相关的方向性。因此,我们认为旁分泌嘌呤能信号协调小鼠生精小管的蠕动复发性收缩,以推动不动精子到达睾丸网。