<P> In the human digestive system, mucus is used as a lubricant for materials that must pass over membranes, e.g., food passing down the esophagus . Mucus is extremely important in the intestinal tract . It forms an essential layer in the colon and in the small intestine that helps reduce intestinal inflammation by decreasing bacterial interaction with intestinal epithelial cells . A layer of mucus along the inner walls of the stomach is vital to protect the cell linings of that organ from the highly acidic environment within it . Mucus is not digested in the intestinal tract . Mucus is also secreted from glands within the rectum due to stimulation of the mucous membrane within . </P> <P> In the human female reproductive system, cervical mucus prevents infection and provides lubrication during sexual intercourse . The consistency of cervical mucus varies depending on the stage of a woman's menstrual cycle . At ovulation cervical mucus is clear, runny, and conducive to sperm; post-ovulation, mucus becomes thicker and is more likely to block sperm . Several Fertility Awareness methods rely on observation of cervical mucus, as one of three primary fertility signs, to identify a woman's fertile time at the mid-point of the cycle . Awareness of the woman's fertile time allows a couple to time intercourse to improve the odds of pregnancy . It is also proposed as a method to avoid pregnancy . </P> <P> Mucus is able to absorb water or dehydrate through pH variations . The swelling capacity of mucus stems from the bottlebrush structure of mucin within which hydrophilic segments provide a large surface area for water absorption . Moreover, the tunability of swelling effect is controlled by polyelectrolyte effect . </P> <P> Polymers with charged molecules are called polyelectrolytes . Mucins, a kind of polyelectrolyte proteoglycans, are the main component of mucus, which provides the polyelectrolyte effect in mucus . The process of inducing this effect comprises two steps: attraction of counter-ions and water compensation . When exposed in physiological ionic solution, the charged groups in the polyelectrolytes attract counter-ions with opposite charges, thereby leading to a solute concentration gradient . An osmotic pressure is introduced to equalize the concentration of solute throughout the system by driving water to flow from the low concentration areas to the high concentration areas . In short, the influx and outflux of water within mucus, managed by the polyelectrolyte effect, contribute to mucus' tunable swelling capacity . </P>

Which type of tissue will likely contain mucous glands