Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, C060

Oral Communications

The calcium signaling network in murine testis

J. A. Fischoeder1, N. Uesaka1, D. Fleck1, M. Spehr1

1. Chemosensation, Institute for Biology II, Aachen, Germany.

The physiological principles underlying spermatogenesis, a crucial step in male fertility, are still largely unexplored. Seminiferous tubules represent the functional units of the testis and orchestrate male germ cell maturation1. In a sequence of tightly coordinated events, germ cells develop from immature spermatogonia to spermatozoa2. Here, we investigate physiological signaling events in different testicular cell types using live-cell imaging. A novel intact in situ preparation of seminiferous tubule sections allows detailed analysis of spontaneous activity in Sertoli cells, putative peritubular cells, and germ cells at different developmental stages. Employing genetically engineered mice that conditionally express a genetically encoded Ca2+ indicator (GCaMP6f) in a cell type-specific manner allows investigation of both Sertoli and germ cell-specific Ca2+ signaling patterns. Sertoli cells generate slow, low-frequency signals. Putative peritubular cells exhibit tonic activity at higher frequencies. Finally, germ cells either display long-lasting Ca2+ signals that occur at low frequencies, or they show transient high frequency signals. Independent of cell type, signal shape is both modulated by extracellular Ca2+ and dependent on intracellular Ca2+ stores. Strikingly, we record some spontaneous Ca2+ signals in each testicular cell type that display intrinsic periodicity. Moreover, cross-correlation analyses indicate testicular networks that appear to coordinate ensemble activity.

Where applicable, experiments conform with Society ethical requirements