Candace Tingen

Sex bias in trials and treatment must end

Gender inequalities in biomedical research are undermining patient care. In the first of three related pieces, Alison M. Kim, Candace M. Tingen and Teresa K. Woodruff call on journals, funding agencies and researchers to give women parity with men, in studies and in the clinic.

The primordial pool of follicles and nest breakdown in mammalian ovaries

The creation of the pool of follicles available for selection and ovulation is a multi-faceted, tightly regulated process that spans the period from embryonic development through to the first reproductive cycle of the organism. In mice, this development can occur in mere weeks, but in humans, it is sustained for years. Embryonic germ cell development involves the migration of primordial germs cells to the genital ridge, and the mitotic division of germ cell nuclei without complete cytokinesis to form a multi-nucleated syncytia, or germ cell nest. Through combined actions of germ cell apoptosis and somatic cell migration, the germ cell nuclei are packaged, with surrounding granulosa cells, into primordial follicles to form the initial follicle pool. Though often dismissed as quiescent and possibly uninteresting, this initial follicle pool is actually quite dynamic. In a very strictly controlled mechanism, a large portion of the initial primordial follicles formed is lost by atresia before cycling even begins. Remaining follicles can undergo alternate fates of continued dormancy or selection leading to follicular growth and differentiation. Together, the processes involved in the fate decisions of atresia, sustained dormancy, or activation carve out the follicle pool of puberty, the pool of available oocytes from which all future reproductive cycles of the female can choose. The formation of the initial and pubertal follicle pools can be predictably affected by exogenous treatment with hormones or molecules such as activin, demonstrating the ways the ovary controls the quality and quantity of germ cells maintained. Here, we review the biological processes involved in the formation of the initial follicle pool and the follicle pool of puberty, address the alternate models for regulating germ cell number and outline how the ovary quality-controls the germ cells produced.

Prepubertal Primordial Follicle Loss in Mice Is Not Due to Classical Apoptotic Pathways

Abstract More than half of the primordial follicles that are formed by Day 6 of postnatal life in the mouse will be eliminated from the ovary by the time of puberty. Apoptosis, a form of programmed cell death, is one mechanism by which these follicles could be actively lost. To investigate whether apoptosis is responsible for the loss of primordial follicles, follicular atresia was examined during the prepubertal period, when follicles die and are cleared from the ovary at an extremely high rate. Four hallmarks of classical apoptosis were measured in follicles present in prepubertal ovaries. The primordial follicle cohort was not positively associated with nuclear condensation or cell shrinkage, activation of caspase 3, cleavage of poly(ADP ribose) polymerase 1 (PARP1), or fragmentation of DNA. These data are consistent with a nonapoptotic pathway that is responsible for small follicle death.

A macrophage and theca cell-enriched stromal cell population influences growth and survival of immature murine follicles in vitro

Innovations in in vitro ovarian follicle culture have revolutionized the field of fertility preservation, but the successful culturing of isolated primary and small secondary follicles remains difficult. Herein, we describe a revised 3D culture system that uses a feeder layer of ovarian stromal cells to support early follicle development. This culture system allows significantly improved primary and early secondary follicle growth and survival. The stromal cells, consisting mostly of thecal cells and ovarian macrophages, recapitulate the in vivo conditions of these small follicles and increase the production of androgens and cytokines missing from stromal cell-free culture conditions. These results demonstrate that small follicles have a stage-specific reliance on the ovarian environment, and that growth and survival can be improved in vitro through a milieu created by pre-pubertal ovarian stromal cell co-culture.

An obscure rider obstructing science: the conflation of parthenotes with embryos in the Dickey-Wicker amendment.

In 1996 Congress passed the Dickey–Wicker Amendment (DWA) as part of an appropriations bill; it has been renewed every year since. The DWA bans federal funding for research using embryos and parthenotes. In this paper, we call for a public discussion on parthenote research and a questioning of its inclusion in the DWA. We begin by explaining what parthenotes are and why they are useful for research on reproduction, cancer, and stem cells. We then argue that the scientific difference between embryos and parthenotes translates into ethical differences, and claim that research on parthenotes is much less ethically problematic. Finally, we contextualize the original passage of the DWA to provide an explanation for why the two were possibly conflated in this law. We conclude by calling for a public discussion on reconsidering the DWA in its entirety, starting with the removal of parthenogenesis from this prohibition of National Institutes of Health (NIH) funding.

Politics and parthenotes

Broad restrictions on funding for human embryo research can stymie work that was unnecessarily precluded by a flawed U.S. law. On 23 August 2010, federal judge Royce Lamberth ruled that President Obamas 2009 executive order expanding federal funding of human embryonic stem cell (hESC) research violated a federal law, the Dickey-Wicker Amendment (DWA), which prevents the funding of research that destroys embryos (1). This congressional prohibition defines a human embryo as “any organism not protected as a human subject” that was “derived by fertilization, parthenogenesis, or any other means from one or more human gametes” (2). The situation is changing rapidly, with court decisions pending and the possibility of legislation that may, for example, exempt hESCs from DWA provisions (3). In danger of being overlooked is the wording about parthenogenesis, which threatens a separate, but potentially fruitful, area of research.

Human Ovarian Tissue Cortex Surrounding Benign and Malignant Lesions

Objective: To quantify the number of follicles in patients with ovarian pathologies, benign and malignant, in pregnant and nonpregnant states and to determine how the presence of ovarian masses and BRCA status affects follicular counts. Materials and Methods: Slides from 134 reproductive-aged women undergoing oophorectomy were examined using light microscopy by 3 independent counters blinded to the diagnosis. In all, 20 patients had cancer, 69 had benign conditions, and 35 patients were BRCA+ or had a strong family history of breast and/or ovarian cancer. In all, 10 women were either pregnant or immediately postpartum. Results: Patients undergoing risk-reducing surgery had significantly decreased follicle count compared to physiologic control. Patients with cancer had significantly decreased counts compared to all other groups. There were no differences within the benign cohort. Conclusions: When compared to benign masses, the cortex surrounding an ovarian malignancy has decreased follicle density. The stretch impact may minimize any impact on total follicle numbers. Furthermore, there may be a proliferation of ovarian stroma, with the same number of follicles spread over a larger surface area. This information is important when counseling women with ovarian masses regarding the use of ovarian tissue cryopreservation.

Practical Parthenote Policy and the Practice of Science

We wrote our article, “An Obscure Rider Obstructing Science: The Conflation of Parthenotes with Embryos in the Dickey-Wicker Amendment,” out of concern for the practical effects of the Dickey-Wicker Amendment (DWA) on the practice of science and to initiate a discussion towards removing parthenotes from the definition of an embryo in it (Rodriguez et al. 2011). We appreciate the beginnings of this discussion through the comments of the four reviewers. We will briefly address what we saw as some of their most important comments in turn. We agree with Strong (2011) that there are good reasons for requiring epistemic rationality when determining public policy and, in fact, one of our main goals in the essay was to highlight the importance of basing policies on empirically supported claims. As it currently stands, the DWA draws upon unsupported factual claims, resulting in 1) a diminished ability to promote the common good and 2) a restriction of the liberty of citizens. First, banning publicly funded research on parthenotes minimizes promotion of the common good by inhibiting the scientific discoveries and knowledge that could greatly benefit society. Second, the DWA restricts the liberty of publicly funded scientists, as well as others involved in this research and/or the liberty of those who could benefit from it. According to Kaebasche (2011), what makes embryos metaphysically different from parthenotes, and thus deserving of moral status, is not genetic uniqueness but rather a complete development program. This point raises interesting ethical questions about the moral status of parthenotes from other species that, unlike human parthenotes, do have a complete development program. In particular, it may lead some to classify human parthenotes as developmentally disabled forms of human life. We agree with Kaebasche that “the best characterization of the human parthenote is not as a deformed human individual, but rather as a biological entity with an ambiguous moral status” (29). In his commentary, DiSilvestro (2011) raises the important distinction between phase sortal—“a type of word

Conceiving ethical gamete and embryo research in a post-Dickey--Wicker USA

In a recent essay in Science, we advocated lifting restrictions on federal funding for research involving parthenogenesis, restrictions that have been placed by a rider, the Dickey--Wicker Amendment (DWA), to every budget for the US Department of Labor, Health, and Human Services, and Education since 1996. We concluded that contribution by calling for the reconsideration of the entire amendment and suggesting that it be removed from the budget. In this contribution, we outline how research using human parthenotes, embryos, stem cells, eggs, or sperm could be ethically funded if the DWA were to be rescinded in the USA. Copyright The Author 2012. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com, Oxford University Press.