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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.