1,721,024 research outputs found
Establishment of ovarian reserve : a quantitative morphometric study of the developing human ovary
No full textOBJECTIVE: To assess directly the dynamics of the formation of the ovarian reserve in the normal human ovary by evaluating the total number of follicles in developing ovaries when folliculogenesis occurs. DESIGN: Histomorphometry-based follicle counts in complete serial tissue sections. SETTING: Functional Anatomy Research Center, University of Milano. PATIENT(S): Thirteen fetuses, neonates, and one 8-month-old infant. INTERVENTION(S): Fifteen ovaries were completely cut, obtaining serial sections. Ovarian volume, volume fractions, density and total number of follicles per ovary were calculated using quantitative morphometric methods. MAIN OUTCOME MEASURE(S): Age-related dynamics of the establishment of ovarian reserve in human developing ovary at the end of the organogenesis. RESULT(S): The ovarian reserve (100,000 follicles at 15 weeks of postconceptional age) increased progressively to 680,000 follicles at 34 weeks. At 8 months of postnatal age the pool was still about 680,000 primordial follicles. CONCLUSION(S): The consistence of the primordial follicle pool during organogenesis shows an exponential increase until month 8 of prenatal life and it is subsequently maintained without modifications at least until month 8 of postnatal life
A new gene encodes a putative GTP-binding protein, escapes X-inactivation and has related sequences on Y chromosome
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Position of follicles in normal human ovary during definitive histogenesis
No full textBackground: Follicular growth in the mammalian ovary follows a geographically determined pattern, but no exhaustive data about their spatial localization in the cortex of human ovary exists. Aim: The aim of this study is to assess the spatial position of the follicles during human ovarian definitive histogenesis using morphometric methods. Subjects: Ovaries removed from four fetuses, five newborns and one 8-month-old child with 46,XX karyotype was used. Outcome measures: The position of the different follicle categories (primordial, primary, secondary and antral) was estimated as percentage distance of the centroid of the follicle from the cortico-medullary boundary. Results: In normal ovaries, during definitive histogenesis, the primordial follicles progressively occupy more peripheral parts of the cortex (on average, 41% of cortical length at 20 weeks of fetal development, 53% at birth, 68% at 8 postnatal months). Primary follicles were crowded in the inner part of the cortex (newborn: 30-40% of cortical length; 8 months: 52% of cortical length). Secondary and antral follicles were sampled in all neonatal specimens and in the 8-month old specimen; they were grouped next to the cortico-medullary boundary. Conclusions: Ovarian development corresponded to a migration of the maximum crowding of follicles from a position next to the medulla towards a more peripheral location. The control of the primordial follicle assembly, recruitment and development are coordinated by locally produced paracrine factors. The action of these factors seems to follow a negative gradient from the cortex toward the medulla
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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