A solution of picroindigo carmine is used to visualize these cells on a “Christmas tree” stain. Swellings called hydroceles (“hydro-seals”) and hematoceles (“hemato-seals”) can interfere with the storage of these cells, which are found in a pouch of serous membrane called the tunica vaginalis. These cells initiate membrane fusion upon binding to (emphasize) another class of cells’ ZP3 receptors. An influx of calcium ions into these (-5[1])cells through the CatSper channel initiates capacitation. The anterior side of these cells contains an acidic vacuole called the acrosome that secretes hydrolytic enzymes to break down a different cell’s zona pellucida (“pel-LOO-sid-uh”). These haploid cells develop in the seminiferous tubules and are stored in the epididymis (“epi-DID-uh-miss”) before traveling through the (10[1])fallopian (-5[1])tubes. For 10 points, name these male gametes that fertilize (10[1])eggs. (10[1])■END■