It is a great pleasure to write in strong support of Valentina Lorenzi for the BSDB Beddington Medal. As Valentina’s PhD supervisor at the Wellcome Sanger Institute, I have had the privilege of mentoring her for over five years. During this time, she has distinguished herself as an exceptional early-career scientist, combining intellectual independence, technical innovation, and deep biological insight, and has made contributions that have already had a significant impact across reproductive developmental biology, immunology, and organoid modelling. Given the depth, originality, and impact of her achievements, she stands among the very best young researchers worldwide.

Through two co-first author publications on human gonadal and reproductive tract development, Valentina resolved previously uncharacterised differentiation trajectories that give rise to sexually dimorphic reproductive organs from an initially shared set of embryonic precursor structures. She also identified candidate molecular programmes guiding early fate specification, sex-specific differentiation, and tissue remodelling during gestation. Her work is characterised by a rare ability to integrate core developmental biology principles directly into computational modelling, embedding knowledge from model organisms and general rules of tissue patterning to interpret sparse and heterogeneous human data in the absence of existing reference atlases.

Valentina’s early work in my laboratory, beginning at the Master’s level, focused on human gonadal development and resulted in a co-first author publication.  In this study, she delineated the hierarchical organization of stem and progenitor cells in the gonads, demonstrating that while core cell states are conserved between humans and mice, many defining molecular markers are species-specific. The observation that cell states appear to evolve at a slower pace than gene expression has implications for our understanding of reproductive disorders such as Differences in Sex Development, where diagnostic frameworks are largely derived from mouse genetics. In this context, Valentina’s atlas provides a valuable source of candidate human-specific markers. In addition, she identified previously unrecognised macrophage populations in the human fetal testes, including a TREM2-positive population with a likely yolk-sac origin and immunoregulatory features. This work has been widely adopted by the community (cited nearly 300 times) and has informed the interpretation of genetic studies of differences in sex development.

Building on this foundational work, Valentina undertook an exceptionally ambitious PhD project: to characterise the development of the entire human reproductive tract across prenatal development, at a time when no cell-resolved reference existed for any of these tissues. This required the integration of data from rare and precious human fetal samples spanning multiple organs, developmental stages, and sexes, each with substantial morphological variability. Through a deeply biologically informed computational framework, Valentina successfully combined single-cell transcriptomics, chromatin accessibility profiling, and spatial genomics to generate the first comprehensive, spatially continuous atlas of Müllerian and Wolffian duct, urogenital sinus and genital tubercle development in humans. The resulting paper represents a major conceptual advance in developmental biology. Valentina’s analyses uncovered putative novel regulators of Müllerian duct emergence and regression, and refined our understanding of HOX-based mesenchymal patterning of the Müllerian and Wolffian ducts. Indeed, she showed unexpected thoracic HOX activity in the rostral mesenchyme of the fallopian tubes and epididymis, challenging canonical view of reproductive tract axial regionalisation. Moreover, this work shed light previously unreported heterogeneity within the epithelium of the fetal fallopian tube and epididymis, revealing that

transcriptional domains associated with sperm capacitation and sperm maturation are established much earlier in development than previously assumed. In the case of the fallopian tube, early regional epithelial identity has direct relevance to current models of high-grade serous ovarian cancer, which implicate the fallopian tube fimbrial epithelium as the cell-of-origin. Finally, Valentina predicted the potential effects of drugs and endocrine disruptors on Müllerian and Wolffian duct development in utero, and her predictions were validated using fetal reproductive organoids.

In addition to her first-author work, Valentina has made substantial contributions to a range of collaborative projects within and beyond my laboratory. She has leveraged her work on human gonadal development to support the Surani laboratory in benchmarking in vitro germline models against her single-cell and spatial atlases. Moreover, Valentina has provided computational and analytical expertise to collaborative studies of the human endometrium and in vitro macrophage development where her input has shaped both experimental design and biological interpretation of complex datasets.

During her PhD, Valentina was also selected to attend the Frontiers in Reproduction course at the Marine Biology Laboratory in Woods Hole, USA to complement her computational expertise with hands-on exposure to classical and modern experimental approaches in reproductive biology. This decision reflects her intellectual maturity and her commitment to developing into a fully rounded, independent scientist.

Beyond her exceptional research accomplishments, Valentina is an outstanding communicator. She has presented her work at several international conferences, demonstrating not only her technical expertise but also her remarkable ability to explain complex scientific concepts in a clear, engaging, and accessible manner. Her presentations are consistently well-received, showcasing her talent for delivering clear, compelling and impactful scientific narratives.

Valentina’s dedication to translating research into real-world impact is equally remarkable. As former president of the Cambridge Femtech Society, she has demonstrated visionary leadership in fostering a community of students and alumni committed to advancing women’s health through technology. Moreover, in her last year of PhD training, Valentina founded and led the creation of the illustrated gynaecological health awareness zine Pelvic Matters (https://ventolab.org/pelvicmatters-outreach/). Pelvic Matters has been distributed across institutes in Cambridge to improve health literacy and reduce stigma. Her initiatives in this space exemplify her drive to ensure that her research benefits society at large.

On a personal level, Valentina is a highly valued member of our team. Her kindness, reliability, and collaborative spirit make her a pleasure to work with, fostering a positive and productive environment. Her enthusiasm and strong interpersonal skills foster harmonious collaborations, further amplifying the impact of her technical expertise.

In summary, Valentina’s doctoral work represents a rare combination of conceptual originality, technical innovation, and biological insight. Her research has already reshaped our understanding of human reproductive tract development, and I am confident that she will continue to make field-defining contributions in the years to come and is therefore an exceptional candidate for the BSDB Beddington Medal.

Roser Vento-Tormo

It is a huge pleasure to nominate Professor Helen Skaer for the BSDB Waddington medal. She is a tireless advocate for our community, and has been teaching, inspiring and supporting developmental biologists for over 50 years. Throughout her career, Helen has been fascinated with understanding how cells are organised/organise themselves to produce physiologically functional organs. Her work unravelling the coordination between diverse cellular behaviours such as cell division, specification, differentiation and migration during morphogenesis has made major contributions to our understanding of organogenesis. Given her outstanding research, inspirational teaching, and her wide regard in the community, we believe she embodies the values the Waddington Medal aims to promote. We are confident that she will give a phenomenal Waddington lecture, that will serve to inspire the whole community.

Helen was one of the very first developmental biologists to tackle the relationship between form and function. During her PhD, Helen focused on understanding how excitable cells are resilient to environmental fluctuations in osmotic and ionic potential, giving her a grounding in cellular physiology. She then moved her focus to epithelial tissues – initially probing the relationship between their structure and their specific physiological attributes. During this phase of her work, she demonstrated that in invertebrates, which lack tight junctions, septate junctions can restrict paracellular flow and so contribute to epithelial tightness. She also pioneered technical developments in the low temperature preservation of material for freeze-fracture, leading to the vitrification of biological samples for electron microscopy.

Through this work, Helen became interested in the cellular activities that underlie the development of epithelial tissues; she set out to understand how intrinsic patterns of gene expression integrate with external signals to define specific cell behaviours. She decided to use the Malpighian (renal) tubules of Drosophila as a model tissue – realising that this system would enable her to combine cellular, genetic and molecular approaches with definable physiological readouts. This choice proved inspired: over the years she has dissected out the distinct cellular and molecular behaviours underlying the development of an epithelial tissue into a physiologically functional organ – pioneering ‘multi-scale’ developmental cell biology long before it became trendy!

Helen’s innovation and determination shine through in both her research and teaching successes. A standout example is from the late 80’s, when Helen demonstrated that the large cells at the tip of the developing renal tubules are mitogenically active, by dissecting open Drosophila embryos and ablating these single cells manually. As students, we loved to hear about Helen ablating renal tubule tip cells by sucking them up finely pulled capillary tubes – it inspired us to think outside the box and believe that anything was possible if you put your mind to it. Using genetic approaches, she then demonstrated that these cells are selected in the tubules by a combination of intrinsic factors and intercellular signalling; through the activity of the proneural transcription factors, whose patterns of expression are regulated by Wnt signalling and by Delta/Notch-mediated lateral inhibition. This was one of the early demonstrations that specific cell lineages outside the nervous system are specified by the refinement of proneural gene expression by lateral inhibition.

Over the years, the work of Helen and her lab has shed light on the regulation of features common to the architecture and function of all epithelia. Many of their findings have contributed to our understanding of vertebrate organogenesis, through their demonstration of conservation in regulatory pathways and networks, in their roles during nephrogenesis and more broadly in the development of tubular epithelia.

Helen has always combined research with an impressive range of teaching and outreach activities. Teaching undergraduate courses in Cambridge, Oxford and Sheffield continuously since 1968, Helen designed and ran courses in developmental biology at all three institutions, including the first interdepartmental course in Oxford across the Biological Sciences/Medicine departments. She has trained over 50 summer vacation and final year students in her lab, many of whom have gone on to do PhDs and some of whom are now University academics teaching developmental/cell biology themselves (e.g. Tanya Whitfield, Keith Brennan, Peter Baumann). Finally, Helen plays a key role in promoting developmental biology in India, giving many talks to college students, and participating in both formal and informal collaborations in the NCBS in Bangalore. She has been a panel member for the India Alliance since its inception – a collaboration between the WT and Indian Department of Biotechnology, supporting and advising scientists across the community.

• Nicolas Tapon
• Kyra Campbell
• Tanya Whitfield
• David Strutt
• Marysia Placzek