In this article, through a theoretical-critical review of contributions from various authors, we ask about the sphere of action of research into disciplinary didactics. Based on reflections made by language and literature didactics and teacher training, we try to identify their priority lines of research. For that purpose, we present an empirical research carried out in the teacher training domain. This study focuses on the teaching and learning practices that are created using the guión conjetural and autorregistros in the training of language teachers at the University of Buenos Aires. Through an interpretative- hermeneutic analysis of the discourses of trainers and students, we identify the teaching processes and the construction of teaching knowledge that are developed using this device. The review of the different theoretical-epistemological postulates and the description of the research on the training devices, gives us elements that allow us to define the didactics as borderline disciplines whose epistemological flexibility allows them to resort to the contributions of other sciences, to appropriate them and to adapt them according to their interests. From this conception, the research activity of didactics tries to explain and understand the real teaching practices in formal (and non-formal) situations and the relationships that subjects build with the object of knowledge.