Endometrial proliferation is stimulated by oestradiol. The precise mechanism is poorly understood, but may be mediated by epidermal growth factor (EGF). The aim of the present study was to assess the effects of oestradiol and EGF on glandular and stromal proliferation in human endometrial cell cultures, and to determine the localization of EGF-like immunoreactivity (EGF-IR) using immunocytochemistry in normal and endometriotic tissue. Endometrium was obtained from women undergoing curettage or hysterectomy for benign disease, or laparoscopy for endometriosis. For tissue culture experiments, enriched glandular and stromal cells were prepared by digestion with collagenase and DNAase, and cultured for 4 days with oestradiol or EGF, both alone and in combination. Immunocytochemical studies were performed using sheep primary antibody against EGF, with binding visualized using the unlabelled antibody--enzyme method. In combination, oestradiol and EGF increased mean cell counts from 1.15 +/- 0.06 and 1.36 +/- 0.05 x 10(5)/ml to 1.68 +/- 0.1 (+46%) and 1.94 +/- 0.16 (+43%) x 10(5)/ml, in proliferative and secretory gland preparations respectively (n = 10, P less than 0.01). No effect was seen in stromal cell preparations; however the stimulation in gland preparations was further augmented after the addition of stromal-conditioned medium. EGF-IR was detected in endometrium from normal women, and in normal and ectopic endometrium from women with endometriosis. EGF-IR was seen in glands and stroma and was not related to the phase of the menstrual cycle. EGF may play a role in the oestrogen-stimulated proliferation of normal and endometriotic endometrium.
The presence of mRNA for epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) was demonstrated in small fragments of human endometrium and decidua by use of the technique of reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers. The presence of mRNA encoding EGF and TGF alpha has not been shown in human endometrium previously. Other studies using conventional techniques, such as Northern blot or in-situ hybridization, showed the presence in low copy number of EGF but not TGF alpha in murine endometrium. Messenger RNA for EGF was not present in peripheral leukocytes or platelets, suggesting an endometrial source for the message. Messenger RNA for TGF alpha was found in these blood components, thus preventing confirmation of the source of TGF alpha mRNA.
While this implant should have important clinical application where chronic treatment is indicated, further work is needed on design of long-term implants so that such preparations can be used when precise return to ovarian activity is required. A fall in inhibin secretion may contribute to the secondary rise in FSH by withdrawal of negative feedback but these events are not closely correlated.
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