title: Menstrual-like breakdown and apoptosis in human endometrial explants.
abstract: BACKGROUND
  Apoptosis occurs in late secretory and menstrual human endometrium and is thought to play an important role in endometrial physiology. Menstrual-like breakdown has been observed in vitro in endometrial explants. The purpose of this study was to assess the role of apoptosis in menstrual-like breakdown in human endometrial explants.
  
  
  METHODS
  Human endometrial tissue was obtained during the mid-secretory phase and cultured with or without estrogen and progesterone. The occurrence of breakdown was assessed by histology. Apoptosis was determined by gel electrophoresis for the detection of DNA fragmentation and by immunohistochemistry using the M30 CytoDEATH and anti-cleaved caspase-3 (CASP3) antibodies for the detection of caspase activity. Expression of BCL2 and BAX was quantified using real-time PCR analysis.
  
  
  RESULTS
  Apoptosis occurred in human endometrial explants at all time-points studied. Cleaved CASP3 and M30 antigen expression increased in all explants, suggesting the involvement of CASP3 in the apoptosis. Low BCL2:BAX ratios were observed in all samples when compared with pre-culture controls. Estradiol and progesterone supplementation of the culture media reduced or eliminated menstrual-like breakdown but did not affect the degree of apoptosis observed.
  
  
  CONCLUSIONS
  The apoptosis observed in endometrium during the late secretory phase and menstrual phase does not appear to be mechanistically related to the tissue breakdown but rather may be involved in the impending remodelling that occurs in the endometrium in the transition from secretory to proliferative phase following the menses.
authors.affiliation: Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: A
authors.initials: A
authors.lastname: Li
authors.forename: J C
authors.initials: JC
authors.lastname: Felix
authors.forename: J
authors.initials: J
authors.lastname: Hao
authors.forename: P
authors.initials: P
authors.lastname: Minoo
authors.forename: J K
authors.initials: JK
authors.lastname: Jain
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000276:immunology / Q000378:metabolism; D053938:DNA Fragmentation; D004717:Endometrium / Q000473:pathology* / Q000502:physiology; D004789:Enzyme Activation; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology*; D008598:Menstruation / Q000502:physiology; D009924:Organ Culture Techniques; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases