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.
Heavy and tractor-trailer truck drivers transport goods from one location to another. Most tractor-trailer drivers are long-haul drivers and operate trucks with a gross vehicle weight (GVW) capacity of more than 26,000 pounds.These drivers deliver goods over intercity routes, sometimes spanning several states.eavy and tractor-trailer truck drivers transport goods from one location to another. Most tractor-trailer drivers are long-haul drivers and operate trucks with a gross vehicle weight (GVW) capacity of more than 26,000 pounds. These drivers deliver goods over intercity routes, sometimes spanning several states.