Germ cells of the mammalian female: A limited or renewable resource?†.

In many non-mammalian organisms, a population of germ-line stem cells supports continuing production of gametes during post-natal life, and germ-line stem cells are also present and functional in male mammals. Traditionally, however, they have been thought not to exist in female mammals, who instead generate all their germ cells during fetal life. Over the last several years, this dogma has been challenged by several reports, while being supported by others. We describe and compare these conflicting studies with the aim of understanding how they came to opposing conclusions. We first consider studies that, by examining marker-gene expression, the fate of genetically marked cells, and consequences of depleting the oocyte population, addressed whether ovaries of post-natal females contain oogonial stem cells that give rise to new oocytes. We next discuss whether ovaries contain cells that, even if inactive under physiological conditions, nonetheless possess oogonial stem cell properties that can be revealed through cell culture. We then examine studies of whether cells harvested after long-term culture of cells obtained from ovaries can, following transplantation into ovaries of recipient females, give rise to oocytes and offspring. Finally, we note studies where somatic cells have been re-programmed to acquire a female germ-cell fate. We conclude that the weight of evidence strongly supports the traditional interpretation that germ-line stem cells do not exist post-natally in female mammals. However, the ability to generate germ cells from somatic cells in vitro establishes a method to generate new gametes from cells of post-natal mammalian females.

Are Screening Tools for Identifying Human Trafficking Victims in Health Care Settings Validated? A Scoping Review.

OBJECTIVE: Although many screening tools, resources, and programs for identifying victims of human trafficking exist, consensus is lacking on which tools are most useful, which have been validated, and whether they are effective. The objectives of this study were to determine what tools exist to identify or screen for victims of human trafficking in health care settings and whether these tools have been validated. METHOD: We conducted a scoping review of the literature on human trafficking identification in health care settings following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) protocol for scoping reviews. We searched the MEDLINE, PsycInfo, Embase, and Scopus databases without language or date limitations. Two independent reviewers screened each citation. We included human research studies in English with populations of all ages, all genders, all geographic locations, and using quantitative and/or qualitative research methods. We excluded studies that were not conducted in a health care setting, review articles, and meta-analyses. We summarized additional screening tools available online and identified through hand-searching. RESULTS: Database searches yielded 8730 studies, of which 4806 remained after removing duplicates. We excluded 4720 articles based on title/abstract review, we reviewed 85 full-text studies for eligibility, and we included 8 articles. Hand-searching revealed 9 additional screening tools not found in the literature. Through our search for validated screening tools, only 6 had been studied for validation in health care settings. CONCLUSIONS: Few studies have evaluated screening tools for identifying victims of human trafficking in health care settings. The absence of a gold standard for human trafficking screening and lack of consensus on the definition of human trafficking make screening tool validation difficult. Further research is required for the development of safe, effective approaches to patient screening.