1. The funnel-shaped opening of a nephridium (excretory tubule) in invertebrates, through which waste products enter the excretory system.
Usage: biology; zoology; technical term

Examples

• The nephrostome of the earthworm's nephridium collects coelomic fluid from the body cavity.
• In annelids, each nephrostome is lined with cilia that help move waste toward the excretory duct.
• The nephrostome serves as the initial filtering structure in the invertebrate excretory system.
• Under the microscope, the nephrostome appears as a delicate, ciliated funnel.
• Biologists study the nephrostome to understand how simple organisms regulate water and waste balance.