title: A stereological study on organelle distribution in human oocytes at prophase I.
abstract: The ultrastructural analysis of human oocytes at different maturation stages has only been descriptive. The aim of this study was to use a stereological approach to quantify the distribution of organelles in oocytes at prophase I (GV). Seven immature GV oocytes were processed for transmission electron microscopy and a classical manual stereological technique based on point-counting with an adequate stereological grid was used. The Kruskal-Wallis test and Mann-Whitney U-test with Bonferroni correction were used to compare the means of the relative volumes occupied by organelles in oocyte regions: cortex (C), subcortex (SC) and inner cytoplasm (IC). Here we first describe in GV oocytes very large vesicles of the smooth endoplasmic reticulum (SER), vesicles containing zona pellucida-like materials and coated vesicles. The most abundant organelles were the very large vesicles of the SER (6.9%), mitochondria (6.3%) and other SER vesicles (6.1%). Significant differences in organelle distribution were observed between ooplasm regions: cortical vesicles (C: 1.3% versus SC: 0.1%, IC: 0.1%, P = 0.001) and medium-sized vesicles containing zona pellucida-like materials (C: 0.2% versus SC: 0.02%, IC: 0%, P = 0.004) were mostly observed at the oocyte cortex, whereas mitochondria (C: 3.6% versus SC: 6.0%, IC: 7.2%, P = 0.005) were preferentially located in the subcortex and inner cytoplasm, and SER very large vesicles (IC: 10.1% versus C: 0.9%, SC: 1.67%, P = 0.001) in the oocyte inner cytoplasm. Further quantitative studies are needed in immature metaphase-I and mature metaphase-II oocytes, as well as analysis of correlations between ultrastructural and molecular data, to better understand human oocyte in vitro maturation.
authors.affiliation: Department of Microscopy,Laboratory of Cell Biology,Multidisciplinary Unit for Biomedical Research - UMIB,Institute of Biomedical Sciences Abel Salazar (ICBAS),University of Porto (UP),Rua Jorge Viterbo Ferreira,228,4050-313 Porto,Portugal.
authors.forename: Ana Sílvia
authors.initials: AS
authors.lastname: Pires-Luís
authors.affiliation: Department of Microscopy,Laboratory of Histology and Embryology,ICBAS-UP,Rua Jorge Viterbo Ferreira,228,4050-313 Porto,Portugal.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rocha
authors.affiliation: Department of Pathology and Cancer Biology and Epigenetics Group,Research Centre-LAB3,Portuguese Oncology Institute-Porto (IPO-P),Rua Dr. António Bernardino de Almeida,4200-072,PortoPortugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Bartosch
authors.affiliation: Department of Microscopy,Laboratory of Cell Biology,Multidisciplinary Unit for Biomedical Research - UMIB,Institute of Biomedical Sciences Abel Salazar (ICBAS),University of Porto (UP),Rua Jorge Viterbo Ferreira,228,4050-313 Porto,Portugal.
authors.forename: Elsa
authors.initials: E
authors.lastname: Oliveira
authors.affiliation: Centre for Reproductive Genetics Alberto Barros (CGR),Av. do Bessa,240,1º Dto. Frente,4100-012 Porto,Portugal.
authors.forename: Joaquina
authors.initials: J
authors.lastname: Silva
authors.affiliation: Centre for Reproductive Genetics Alberto Barros (CGR),Av. do Bessa,240,1º Dto. Frente,4100-012 Porto,Portugal.
authors.forename: Alberto
authors.initials: A
authors.lastname: Barros
authors.affiliation: Department of Microscopy,Laboratory of Cell Biology,Multidisciplinary Unit for Biomedical Research - UMIB,Institute of Biomedical Sciences Abel Salazar (ICBAS),University of Porto (UP),Rua Jorge Viterbo Ferreira,228,4050-313 Porto,Portugal.
authors.forename: Rosália
authors.initials: R
authors.lastname: Sá
authors.affiliation: Department of Microscopy,Laboratory of Cell Biology,Institute of Biomedical Sciences Abel Salazar (ICBAS),University of Porto (UP),Rua Jorge Viterbo Ferreira,228,4050-313 Porto,Portugal.
authors.forename: Mário
authors.initials: M
authors.lastname: Sousa
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D022162:Cytoplasmic Vesicles / Q000648:ultrastructure; D018871:Endoplasmic Reticulum, Smooth / Q000648:ultrastructure; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D049469:Meiotic Prophase I; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D008928:Mitochondria / Q000648:ultrastructure; D009865:Oocytes / Q000254:growth & development / Q000648:ultrastructure*; D015388:Organelles / Q000648:ultrastructure*; D015044:Zona Pellucida / Q000648:ultrastructure
keywords: Cell polarity; Human germinal vesicle oocytes; Organelle distribution; Stereology; Ultrastructure