lactiferous duct

Examples of lactiferous duct in the following topics:

• Mammary Glands

  • These alveoli join to form groups known as lobules, and each lobule has a lactiferous duct that drains into openings in the nipple.
  • All the milk-secreting tissue leading to a single lactiferous duct is called a simple mammary gland; a complex mammary gland is all the simple mammary glands serving one nipple.
  • Lactiferous duct development occurs in females in response to circulating hormones, first during pre- and postnatal stages and later during puberty.
  • When the lactiferous duct tree is almost ready, alveoli are differentiated from luminal epithelial cells and added at the end of each branch.
  • However, a functional lactiferous duct tree can be reformed when a female is pregnant again.

• Lymph Trunks and Ducts

  • Lymphatic trunks then drain lymph fluid into the lymph ducts, the final part of the lymphatic system.
  • Two lymph ducts receive lymph from the lymph trunks.
  • The thoracic duct drains into to the left subclavian vein while the right duct drains into the right subclavian vein, both at the junction between the respective vein and the jugular vein.
  • The lymph ducts each have internal valves at their junction with the subclavian vein.
  • These function similarly to other lymphatic valves and prevent venous blood from flowing into the lymph duct.

• Associated Organs

  • These eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct.
  • The cystic duct, from the gallbladder, joins with the common hepatic duct to form the common bile duct.
  • The common bile duct and the pancreatic duct enter the duodenum together.
  • The gallbladder is connected to the main bile duct through the cystic duct, which in turn connects to the duodenum.
  • The liver and gallbladder are connected via the cystic duct, the liver and pancreas are connected via the pancreatic duct, and all three enter the duodenum at the common bile duct,

• Testes Ducts

  • Testes ducts, which include the seminiferous tubules and vas deferens, are involved in the creation or transportation of sperm.
  • The efferent ducts connect the rete testis with the initial section of the epididymis.
  • In humans and other large mammals, there are approximately 15-20 efferent ducts which occupy nearly one-third of the head of the epididymis.
  • Two ducts connect the left and right epididymis to the ejaculatory ducts in order to move sperm.
  • A modern procedure that does not include cutting the ducts involves injecting an obstructive material into the ductus to block the flow of sperm.

• Embryological and Fetal Events

  • The reproductive organs are developed from the Wolffian ducts in males and the Mullerian ducts in females.
  • These embryonic structures are the Wolffian and Müllerian ducts, also known as mesonephric and paramesonephric ducts, respectively.
  • The Wolffian duct remains as the duct in males, and the Müllerian as that of the female.
  • Shortly after the formation of the Wolffian ducts a second pair of ducts is developed; these are the Müllerian ducts.
  • In the male the Müllerian ducts atrophy, but in the female the Müllerian ducts persist and undergo further development.

• Pancreatic Juice

  • Pancreatic secretion consists of an aqueous bicarbonate component from the duct cells and an enzymatic component from the acinar cells.
  • A variety of factors cause a high pressure within pancreatic ducts.
  • Pancreatic duct rupture and pancreatic juice leakage cause pancreatic self-digestion.
  • A schematic diagram that shows pancreatic acini and the ducts where fluid is created and released.

• Anatomy of the Gallbladder

  • The neck tapers and connects to the biliary tree via the cystic duct, which then joins the common hepatic duct to become the common bile duct.
  • The muscularis is a layer of smooth muscular tissue that helps the gallbladder contract and squirt its bile into the bile duct.

• Development of Hearing and Balance

  • The utricular division of the auditory vesicle also responds to angular acceleration, as do the endolymphatic sac and duct that connect the saccule and utricle.
  • The vestibular wall will separate the cochlear duct from the perilymphatic scala vestibuli, a cavity inside the cochlea.
  • The basilar membrane separates the cochlear duct from the scala tympani, a cavity within the cochlear labyrinth.
  • The lateral wall of the cochlear duct is formed by the spiral ligament and the stria vascularis, which produces the endolymph.
  • The hair cells develop from the lateral and medial ridges of the cochlear duct, which together with the tectorial membrane make up the organ of Corti.

• Accessory Sex Glands

  • The excretory duct of the seminal gland opens into the vas deferens as it enters the prostate gland.
  • Acidic ejaculate (pH <7.2) may be associated with ejaculatory duct obstruction.
  • Each lobule opens into a duct that joins with the ducts of other lobules to form a single excretory duct.
  • This duct is approximately 2.5 cm long and opens into the urethra at the base of the penis.
  • Prostate with seminal vesicles and seminal ducts, viewed from the front and above, including the urethra, seminal vesicle, vas deferens, ampulla, ejaculatory duct, and isthmus.

• Glandular Epithelia

  • An exocrine gland is distinguished by the fact that it excretes its essential product by way of a duct to some environment external to itself, be it either inside the body or on a surface of the body.
  • It secretes its essential product without the use of a duct directly into the bloodstream or else by diffusion into its surrounding tissue (paracrine signaling) where it often affects only target cells near the release site.
  • The exocrine glands secrete their products into a duct that then delivers the product to the lumen of an organ or onto the free surface of the epithelium.