which stop the sperm from binding to the zona pellucida and ultimately from fertilizing the ovum. Another vaccine that has been investigated is one against human chorionic gonadotropin (hCG). In phase I and early phase II human clinical trials, an experimental vaccine consisting of a dimer of β-hCG, with the tetanus toxoid (TT) as an adjuvant, produced antibodies against hCG in the small group of women immunized. The anti-hCG antibodies generated were capable of neutralizing the biological activity of hCG. Without active hCG, maintenance of the uterus in a condition receptive for implantation is not possible, thereby forestalling pregnancy. As only 80% of the women in the study had a level of circulating anti-hCG sufficient to prevent pregnancy, further development of this approach will be to enhance the immunogenicity of the vaccine, in order that it produces a reliable and consistent immune response in a higher proportion of women. Towards this goal, vaccine variations using a peptide of β-hCG that is uniquely specific to hCG, while absent in other hormones – luteinizing hormone (LH), follicle-stimulating hormone (FSH), and fhyroid-stimulating hormone (TSH) – are under investigation in animal models, for their possible enhancement of responses. Research Studying the female reproductive tract, especially in humans, allows for a better understanding of the immune system, including during pregnancy. However, studying the female reproductive tract has been a challenging area of research due to existing limitations in the in vitro and in vivo tools available. Ethical concerns is another contributing factor in hindering the study of reproductive immunology. Given such limitations, research in this field relies on stem cell culture and technological advancements by allowing scientists to conduct research on organoids instead of living human subjects. In 2018, a Review study concluded that organoids can be used to model organ development and disease. Other studies have concluded that with further technological advancements, it is possible to create a detailed 3D organoid model of the female reproductive tract which introduces a more efficient method to conduct research and collect data in the fields of drug discovery, basic research and essentially reproductive immunology. Single-cell technologies The maternal-fetal interface has the ability to protect against pathogens by providing reproductive immunity. Simultaneously, it is remodeling the tissues needed for placentation. This unique feature of the maternal-fetal interface suggests that the decidual immunome, or the immune function of the female reproductive tract, is not fully understood, yet. In order