one of a group of cells that develop in the walls of the seminiferous tubules. Spermatogenic cells include spermatogonia, spermatocytes, and spermatidsâall of which are transitional forms between primary sexual cells and spermatozoa.
long-haul optics. Long-haul optics refers to the transmission of visible light signals over optical fiber cable for great distances, especially without or with minimal use of repeaters. Normally, repeaters are necessary at intervals in a length of fiber optic cable to keep the signal quality from deteriorating to the point of non-usability. In long-haul optical systems, the goal is to minimize the number of repeaters per unit distance, and ideally, to render repeaters unnecessary.
An earlier Cisco technology that enabled Ethernet to extend into buildings with older CAT 1, 2 or 3 twisted pair wires. Using Cisco Long Reach Ethernet (LRE) equipment, Ethernet could transmit up to 5,000 feet at 15 Mbits/sec. Long Reach Ethernet was similar to and was superseded by VDSL (see DSL). See Ethernet.