title: Breast histomorphometry of rats treated with estrogen and/or progestogen.
abstract: OBJECTIVE
  To evaluate the breast histomorphometric changes in rats treated with estrogen and/or progestogen for a short period of time.
  
  
  METHODS
  Forty oophorectomized rats were divided into four groups: GC, vehicle; GE, treated with estradiol benzoate (37.6 mg/animal); GP, treated with medroxyprogesterone acetate (11.2 mg/animal) and GEP, treated with estradiol benzoate (37.6 mg/animal) plus medroxyprogesterone acetate (11.28 mg/animal). In GE group, estradiol was administered subcutaneously for seven days; in GEP group, estradiol was administered once in a day for the first seven days and the progestogen over the next 23 days both subcutaneously. Twenty-four hours after the last hormone administration, the animals were killed upon deep anesthesia and the first inguinal breasts were removed, fixed in 10% formaldehyde and processed to be included in paraffin, with the sections being stained by hematoxylin-eosin. Morphology and the area occupied by mammary parenchyma were assessed, with the data undergoing analysis of variance followed by the Kruskal-Wallis test (p < 0.05).
  
  
  RESULTS
  The control group breasts were found atrophic and, in GE and GEP group animals, typical alveoli with secretion inside are present; in progestogen-treated animals (GP), alveoli formed by large cells occupying almost the entire alveolar lumen are noted. Morphometric analysis showed a larger mammary parenchyma area in hormone-treated animals (GE = GP > GEP > GC; p < 0.05).
  
  
  CONCLUSIONS
  Estradiol and progestogen had a proliferative effect on mammary parenchyma. However, prior estradiol administration changes the progestogen action on rat mammary tissue.
authors.affiliation: Department of Gynecology, UNIFESP and Department of Obstetrics and Gynecology, FMUSP – São Paulo, SP, Brazil.
authors.forename: Sueli Maria Preda Dos Santos
authors.initials: SM
authors.lastname: Torres
authors.forename: Ricardo Santos
authors.initials: RS
authors.lastname: Simões
authors.forename: Maria Cândida Pinheiro
authors.initials: MC
authors.lastname: Baracat
authors.forename: Regina Célia Teixeira
authors.initials: RC
authors.lastname: Gomes
authors.forename: José Maria
authors.initials: JM
authors.lastname: Soares Júnior
authors.forename: Adriana Aparecida Ferraz
authors.initials: AA
authors.lastname: Carbonel
authors.forename: Edmund Chada
authors.initials: EC
authors.lastname: Baracat
mesh_terms: D000818:Animals; D000075202:Contraindications; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D005260:Female; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000473:pathology; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology*; D010052:Ovariectomy; D011372:Progestins / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011372:Progestins; C074283:estradiol 3-benzoate; D004958:Estradiol; D017258:Medroxyprogesterone Acetate