Date of Award

1982

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

Previous studies indicated that a permeability barrier between blood and the uterine lumen might exist in rats. The abilities of selected radiolabelled test substances to enter the uterine lumen were assessed by comparing radioactivity concentrations in fluid (secreted or instilled) recovered from the uterine lumen with those in serum, at fixed times after single intravenous injections of a test substance.;Initial experiments conducted in immature, ovariectomised, estradiol-treated rats revealed that a barrier to {lcub}('3)H{rcub}-sucrose, {lcub}('3)H{rcub}-inulin, and {lcub}('125)I{rcub}-bovine serum albumin exists between blood and the uterine lumen which impeded the entry of these substances into the uterine lumen. Further experiments showed that this barrier is characterised by exhibiting variable restrictiveness which is modulated by these hormones. The relative abilities of certain substances to cross this barrier were investigated. Direct comparisons between {lcub}('3)H{rcub}-mannitol, {lcub}('3)H{rcub}-sucrose, and {lcub}('3)H{rcub}-inulin indicated that {lcub}('3)H{rcub}-mannitol crossed the blood-uterine lumen barrier more readily that {lcub}('3)H{rcub}-sucrose or {lcub}('3)H{rcub}-inulin. Since these hydrophilic substances differ from each other primarily in molecular size, this observation suggested that this barrier is characterised by restricting selectively some substances according to molecular size. Similar comparisons revealed that {lcub}('14)C{rcub}-antipyrene and {lcub}('14)C{rcub}-barbital crossed this barrier without restriction, whereas {lcub}('3)H{rcub}-mannitol was highly impeded. Since these compounds differ from each other only slightly in molecular weight but greatly in lipid solubility, it was concluded that this barrier is characterised by restricting selectively some substances according to lipid solubility. Uterine tissue radioactivity concentrations were compared with those in serum in an attempt to ascertain the location of the blood-uterine lumen barrier. The interpretation given to the results obtained is that this barrier is located at or near the uterine epithelium and has an extracellular locus. Hence, this barrier is characterised by being able to isolate the uterine lumen from uterine extracellular fluid by virtue of its epithelial paracellular location.;The functional significance of blood-uterine lumen barrier is discussed in terms of the importance of the uterine luminal environment in reproduction.

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