tubuli

Tubulus (plural tubuli) is a Latin term widely used in anatomy to describe a narrow, tube-like structure. In histology, many organs contain tubuli as functional units responsible for transport, secretion, or collection of fluids. The term is used across organ systems, and specific names usually modify tubulus to indicate location or function.

In the kidney, the nephron includes several tubular segments: the proximal tubule, the loop of Henle, the distal tubule, and the collecting duct. These tubuli process filtrate produced by the glomerulus, reabsorbing water, ions, and nutrients and secreting waste, under hormonal control. The proximal tubule has abundant microvilli to maximize reabsorption; the collecting duct concentrates urine in response to antidiuretic hormone.

In the male reproductive system, the seminiferous tubules within the testes are coiled ducts where sperm are produced; they drain into tubuli recti and the rete testis.

Tubuli are also found in many exocrine glands and other organs as components of ducts or secretory units, illustrating the general function of forming a tube that conduits fluids.

Etymology and usage: tubulus means a small tube; tubuli is the plural form used in anatomical nomenclature, often in combination with organ names (for example, tubuli renales, tubuli seminiferi).