ESTROGEN-INDUCED PEROXIDASE SECRETION FROM THE ENDOMETRIAL EPITHELIUM- A POSSIBLE FUNCTION FOR THE LUMINAL ENZYME

Estrogen induced peroxidase (EIP) activity revealed as a diaminobenzid ine-H2O2 product in electron micrographs is apparent within cisternae of the RER and in large dilated apical vesicles, of which only a few h ave been seen to open into the uterine lumen. EIP activity is infreque ntly present in the trans cisternae of the rather diminutive Golgi com plex in uterine epithelial cells from 12-72 h after treatment with est rogen. EIP activity is, however, prominent on the surface of microvill i of epithelial cells and as deposits in the lumen. Desalted uterine f luid (72 h) isolated by rotofor (Biorad) and analysed on isoelectric f ocusing gels that were stained with the diaminobenzidine-H2O2 reaction , reveal the existence of at least 6 peroxidase isoelectric variants w ith isoelectric points between pI 3.5 and pI 5.0. In similar preparati ons doubly-stained by diaminobenzidine-H2O2 and silver, peroxidase pos itive bands are enhanced, along with other isoelectric variants in the acidic pI range. In SDS-PAGE preparations, five prominent proteins ra nging from 29-115 kD are present in 72 h uterine fluid. Luminal EIP co ats the surface microvilli of the reproductive tract cells, and of via ble spermatozoa incubated in uterine fluid. Peroxidase coated bacteria appear to be in the process of decay, and enzyme activity is present on the surface of most spermatozoa. It is not yet determined if EIP ha s bactericidal, spermicidal or capacitation functions.