title: Histochemical and morphological examination of proliferation and apoptosis in human first trimester villous trophoblast.
abstract: BACKGROUND
  Our present knowledge about trophoblast turnover in human first trimester placental villi based on multiparametric examination of proliferation and apoptosis is limited.
  
  
  METHODS
  Human villous placentae collected during 6, 7 and 8 weeks (n = 10/each group) of gestation were examined for trophoblast proliferation and apoptosis based on quantitative analyses of immunopositive Fas, tumor necrosis factor receptor 1 (TNFR1), cytokeratin 18 fragment (18f), number of proliferating cell nuclear antigen (PCNA), Ki67 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) positive nuclei, scores of mitotic and apoptotic indices and ultrastructural characteristics.
  
  
  RESULTS
  Mitotic index in cytotrophoblast higher (P < 0.05) at 6 week compared with 7 and 8 weeks of gestation showed significant (P < 0.05) negative correlation between its prevalence and gestational age. Syncytiotrophoblast exhibited higher number of TUNEL positive nuclei (P < 0.01), TUNEL positive apoptotic nuclei (P < 0.05) and apoptotic index (P < 0.05) compared with cytotrophoblast at same gestational age. Positive correlations found between cytokeratin 18f and apoptotic index (P < 0.01), Fas and apoptotic index (P < 0.01), TUNEL positive nuclei and apoptotic index (P < 0.05), cytokeratin 18f and Fas (P < 0.01), whereas cytokeratin 18f (P < 0.05) and Fas (P < 0.05) showed positive correlation only with TUNEL positive apoptotic nuclear data. Phalangeal intrusions of syncytiotrophoblast between transitional cytotrophoblasts showed apposed plasma membranes bearing thickened membrane leaflets, inter-membranous gaps enclosing membranous invaginations, liposome-like particles; patches of membrane seen to be dissolved resulting in cytoplasmic continuity typical of syncytial formation.
  
  
  CONCLUSIONS
  Cellular remodeling of first trimester villous placenta requires a complex homeodynamics involving proliferation in cytotrophoblast, development-associated syncytialization and apoptosis in syncytiotrophoblast.
authors.affiliation: Department of Physiology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Manisha
authors.initials: M
authors.lastname: Kar
authors.forename: Debabrata
authors.initials: D
authors.lastname: Ghosh
authors.forename: Jayasree
authors.initials: J
authors.lastname: Sengupta
mesh_terms: D017209:Apoptosis; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D053538:Keratin-18 / Q000096:biosynthesis; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008081:Liposomes / Q000737:chemistry; D008938:Mitosis; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000096:biosynthesis; D014327:Trophoblasts / Q000473:pathology* / Q000502:physiology*; D019014:fas Receptor / Q000096:biosynthesis
chemical_list: D053538:Keratin-18; D019394:Ki-67 Antigen; D008081:Liposomes; D018809:Proliferating Cell Nuclear Antigen; D047888:Receptors, Tumor Necrosis Factor, Type I; D019014:fas Receptor