Human corpus luteum: human chorionic gonadotropin receptors during ectopic pregnancy.

OBJECTIVE

To examine hCG receptor levels and binding kinetics in corpora lutea (CL) from tubal pregnancies.

DESIGN

Corpus luteum from tubal pregnancies, term normal pregnancies, and midluteal phase were obtained and compared for hCG binding.

SETTING

Department of Obstetrics and Gynecology, University Hospital.

INTERVENTIONS

Corpus luteum were obtained at elective cesarean section at term, tubal ligation, or surgery for ectopic pregnancy (EP).

MAIN OUTCOME MEASURES

Human chorionic gonadotropin receptor levels, dissociation and association constants using saturation binding assay, and Scatchard analysis.

RESULTS

Corpus luteum from late tubal pregnancies (> 7 weeks) and term intrauterine pregnancies had undetectable hCG binding. Corpus luteum from early tubal pregnancies (< 6 weeks) had significantly reduced hCG receptors with higher dissociation constants than from midluteal phase CL.

CONCLUSIONS

Significant reduction of hCG receptors with accelerated binding dissociation may be the basis of CL dysfunction in some EPs.