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1. an obstruction.
2. a partition between two fluid compartments in the body.
3. a covering used to prevent contact with body fluids.
alveolar-capillary barrier (alveolocapillary barrier) see under membrane.
blood-air barrier alveolocapillary membrane.
blood-aqueous barrier the physiologic mechanism that prevents exchange of materials between the chambers of the eye and the blood.
blood-brain barrier see blood-brain barrier.
blood-gas barrier alveolocapillary membrane.
blood-testis barrier a barrier separating the blood from the seminiferous tubules, consisting of special junctional complexes between adjacent Sertoli cells near the base of the seminiferous epithelium.
barrier methods contraceptive methods such as condoms and diaphragms in which a plastic or rubber barrier blocks passage of spermatozoa through the vagina or cervix. See discussion under contraception.
placental barrier the tissue layers of the placenta which regulate the exchange of substances between the fetal and maternal circulation.
an occluding barrier formed by Sertoli cells in the seminiferous tubules of the testis, which separates the more mature cells of spermatogenesis in the adlumenal compartment of the tubule from blood-derived products in the basal compartment.
an obstruction; a partition between two fluid compartments in the body.
the physiological mechanism that prevents exchange of materials between the chambers of the eye and the blood.
blood-brain barrier (BBB)
the barrier separating the blood from the brain parenchyma. See also blood-brain barrier.
differs from the blood-brain barrier anatomically, in that it consists of the epithelium of the choroid plexuses, but has similar permeabilities.
endothelium of the retinal capillaries and cells of the retinal pigment epithelium form a nonfenestrated barrier between choroidal tissue fluid and retinal tissue fluid.
suggested by the presence of plasma proteins of small molecular size and catabolic products of articular cartilage in synovial fluid.
a barrier separating the blood from the seminiferous tubules, consisting of special junctional complexes between adjacent Sertoli cells near the base of the seminiferous epithelium. It provides an extravascular environment which is also adluminal and permits selective nourishment of spermatozoa.
a rubber boot worn by horses to protect the hoof against trauma.
a nonwettable cream used on the skin of the hands and arms to protect against staining and odor absorption when handling offensive materials, e.g. delivery of an emphysematous fetus.
gastric mucosal barrier
the poorly defined mechanism that prevents back diffusion of hydrochloric acid from the stomach into the tissues of the stomach wall.
the protective properties of skin and its relative impenetrability by noxious substances as well as medicaments; usually considered a function of keratinized epithelial cells aided by surface lipids.
barrier teat dip
material which leaves a physical protective coat on the teat between milkings, used mostly to protect against infection for long periods, e.g. during the dry period. Most contain acrylic, latex or collodion.