M echanical properties of the micro-environment are fundamental in orchestrating normal tissue function, disease progression, and organismal development. Studies of mechanotransduction in cultured cells on artificial substrates have revealed underlying principles, but the in vivo roles of mechanotransduction remain unclear. We recently reported that the Caenorhabditis elegans sperma-theca-a myoepithelial tube composed of a cell monolayer-may be mechano-sensitive. Live imaging with the genetically encoded calcium indicator GCaMP revealed that oocyte-induced stretching of the spermatheca resulted in calcium oscillations and constriction of the tube. FLN-1/filamin, a mechanosensitive cyto-skeletal scaffolding protein, is required to correctly trigger the calcium tran-sients. PLC-1/phospholipase C-epsilon and ITR-1/IP 3 receptor are required to produce the calcium transients, and may function downstream of filamin. In addition to providing important insights into the biology of C. elegans, our studies offer a novel and genetically tractable model for studying mechanotransduc-tion in a myoepithelial tissue. Overview of the C. elegans Spermatheca Anatomy and Function The spermatheca connects the oviduct with the uterus and serves as the site of sperm storage and fertilization. 1 A mono-layer of 24 myoepithelial cells surrounded by a basement membrane forms the sper-matheca. 2 The distal spermatheca is a