Impact of Peer-Assisted Learning in Histology and Embryology of a Medical Course: A Mixed-Methods Study

Background: Peer-assisted learning (PAL) is used in medical education. Its impact in basic medical sciences remains unexplored, namely considering the perspectives of all the populations involved: students, undergraduate teaching assistants (UTAs), and faculty members. We evaluated the educational impact of a PAL programme in Histology and Embryology in a medical course at the Faculty of Medicine of the University of Porto (FMUP). Methods: A cross-sectional convergent mixed-methods study was conducted in the Histology and Embryology course. Tailored online questionnaires comprising Likert-type items and open-ended questions were replied to by students attending theoretical–practical classes with UTAs, the UTAs, and the professors. Internal consistency was assessed using Cronbach’s alpha. Students’ theoretical–practical examination scores were compared between classes with and without UTAs using the Mann–Whitney U test, and effect size (r) was calculated to estimate the magnitude of differences observed. Results: Students (n = 190) reported highly positive perceptions regarding the creation of a more approachable learning environment, clarification of doubts, and identification of histological structures and strongly recommended the extension of UTAs to other courses of the medical school. UTAs (n = 17) described gains in disciplinary understanding, broader perspectives on the medical curriculum, communication and public-speaking skills, teamwork, leadership, self-confidence, and interest in academic careers. Professors (n = 6) valued PAL for improving individual support, facilitating time management, and contributing to UTA training, while highlighting the need for structured pedagogical preparation. Students attending classes with UTAs achieved significantly higher theoretical–practical examination scores (p = 0.04; effect size r = 0.12). Conclusions: PAL was perceived as highly beneficial by all groups involved in the project, enhancing the learning environment, supporting knowledge consolidation, and developing pedagogical and interpersonal skills. A grade analysis indicated that PAL was associated with improved academic performance. These findings reinforce the value of integrating PAL initiatives into preclinical medical education while highlighting the importance of sustained tutor preparation and supervision.