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Because of the great usefulness of estrogen receptor determinations in selecting therapy for breast cancer patients a number of histochemical and immunohistochemical methods for visualizing bound estrogen in cells and tissue sections have been proposed. We discuss all of these histochemical methods in the light of the known properties of the estrogen receptor and other estrogen binders, and we consider some criteria that must be met if such methods are to be considered valid for receptor. In spite of the great potential value of histochemical methods, we are forced to conclude that, in their present form, none of them are likely as yet to be detecting estrogen receptor.

Monoclonal antibodies against a 24,000 dalton intracellular estrogen-regulated protein in human breast cancer cells were used to study storage conditions and the effects of monoclonal antibody concentrations on immunohistochemical antigen localization. Both hybridoma supernatants and ascites fluid obtained from mice injected with hybridoma cells were used as sources of monoclonal antibodies; the monoclonal antibodies in the ascites fluid were concentrated and purified. Both antibody preparations were stored at 4, -20, or -70 degrees C and periodically tested for activity at these storage conditions. There was no difference in activity for the antibodies between storage at -20 and -70 degrees C. However, when highly diluted antibody was stored at 4 degrees C, the activity was lost within 2 weeks if carrier proteins were not added. These monoclonal antibodies were applied to immunohistochemical staining of different mouse and human tissues processed for routine paraffin sections, using the avidin-biotin-peroxidase procedure. A monoclonal antibody of unrelated specificity was used as control. When these antibodies were used at high concentrations, all the different tissues examined were immunostained. With reduction of the antibody concentration, an immunohistochemical dissection of the tissues was seen until specific immunostaining was reached. When even more highly diluted monoclonal antibody was used, heterogeneity in the staining pattern became very high. On the basis of these results, certain immunohistochemical criteria are proposed for the selection of the optimum concentration of monoclonal antibodies for specific antigen detection.

The antiestrogen tamoxifen, administered to newborn female rats, caused gross abnormalities in reproductive development. Vaginal opening was early, cycles were absent and at 4 months of age all ovaries and uteri were atrophic while oviducts showed severe squamous metaplasia with abscess formation. No overt malignancy was detected at this early age, but these results and similar findings with nafoxidine and clomiphene may suggest caution in the use of antiestrogens and similar compounds during possible pregnancy.

The autoregulation of testicular human chorionic gonadotropin (hCG) binding sites was studied in two strains of mice known to differ in their endocrine and reproductive characteristics (C57BL/10J and DBA/2J), and in their F1 progeny (B10D2F1). Basal hCG binding levels were higher in C57BL/10J than in DBA/2J mice, while B10D2F1 mice had intermediate levels. Twenty-four h after injection, hCG produced dose-related changes in hCG binding in C57BL/10J and B10D2F1 mice not observed in DBA/2J mice. However, 72 h after treatment with hCG there was a decrease in hCG binding in all the strains studied. These results suggest the participation of genetic factors in determining basal levels, dose-related changes and temporal response of testicular hCG binding sites to hCG administration. Androgen receptor levels were measured in the same strains of mice. DBA/2J mice had higher receptor levels in the kidney and coagulating gland, and lower levels in the hypothalamus and seminal vesicle when compred to C57BL/10J mice. B10D2F1 mice had androgen receptor levels similar to those measured in C57BL/10J mice in all tissues studied, with the exception of the coagulating gland, where levels were similar to those observed in DBA/ZJ mice. These observations may indicate the existence of several loci coding for androgen receptors, with only one being expressed per tissue

WHEN oestrogen molecules enter a target cell they are bound by specific receptors in the cytoplasm which then enter the nucleus carrying the hormone1. In the nucleus the hormone-receptor complexes bind to acceptor sites, where they presumably initiate the sequence of events comprising the hormone response.