The role of calcium ions (Ca²⁺) as the universal signal for egg activation has been acknowledged for nearly a century, with subsequent research unveiling the necessity of Ca²⁺oscillations for egg activation in mammals. However, understanding the precise triggering pathway(s) behind the prolonged and protracted Ca²⁺ responses during mammalian fertilization posed a challenge due to limited methods to investigate these events and knowledge of the mechanisms involved. Pivotal breakthroughs came with the discovery of fluorescent dyes to monitor ion changes and that injecting sperm extracts into eggs replicated fertilization-induced oscillations and egg activation. The culminating demonstration of this process was the birth of offspring through Intra Cytoplasmic Sperm Injection (ICSI) without previous interaction of the gametes. This milestone was molecularly underpinned by the identification of sperm-specific PLCζ, whose injection in the form of mRNA, induced Ca²⁺ oscillations identical to those observed during fertilization. Interestingly, infertile patients with repeated ICSI failure exhibited the absence of PLCζ expression or point mutations on the sequence of PLCζ, suggesting that PLCζ represented the main, and possibly sole Ca²⁺-active factor in mammalian sperm. However, this notion was challenged by the observation that Plcζ-null males initiated subdued Ca²⁺ oscillations and displayed subfertility, indicating the existence of an additional factor(s) in mouse sperm triggering sufficient Ca²⁺ responses to support embryo development. Yet, its identity and involvement during fertilization with wild-type sperm remain unknown. Our contribution here is to identify the remaining Ca²⁺ active component(s) in sperm that could function as a “backup mechanism” of egg activation. This contribution is significant because it is a necessary step in our goal to identify all the sperm molecules that induce the Ca²⁺ signal required for embryo development. TRPM7 is expressed ubiquitously across cell types and tissues, and exhibits diverse subcellular localization, including the plasma membrane, cytoplasm, and nucleus, suggesting multifunctionality. Numerous studies have highlighted the essential role of TRPM7 in numerous cell types and organs, including a vital role in pre-implantation embryo development, where its absence causes embryonic death. Significantly, its molecular mechanism in embryogenesis remains unknown. Additionally, despite its fundamental role in fertility, the expression and localization of TRPM7 in gametes and embryos have not been fully elucidated. Our contribution seeks to precisely identify the expression, localization, and molecular mechanism of TRPM7 in embryo development, a crucial step in understanding the function of this essential channel regulating divalent cation homeostasis during embryogenesis. Overall, this contribution holds significant implications for perfecting parthenogenetic methods to address egg activation failure, enhancing embryo development, identifying new indicators of male and female fertility, and exploring potential contraception targets. This study helped in understanding the molecules and regulatory mechanisms initiating embryo development in these species and advances our knowledge substantially.