El conocimiento didáctico del contenido en el profesor de matemáticas: ？una cuestión ignorada?

named by lee shulman as the missing paradigm, pedagogical content knowledge (pck) has shown a formidable development in recent years as a didactical research field. despite that, since now, it has not been considered important enough in order to be a domain of knowledge included in the courses of teachers' instruction nor as an object of research in mathematics education at mexico. in this paper, it is shown, firstly, how pck has arisen, its meaning, its foundation and its theoretical nature. secondly, the elements of pck are described, pointing out at their relevance and implications as an object of study and as a conceptual framework for teachers training. thirdly, the research done is revised from an international point of view, and field of mathematics education in mexico is included with the result of the inexistence of this type of research, so the paper concludes the necessity of studying the knowledge of mathematics teachers from this type of research, with conceptual frameworks that allow us to understand how mathematical meanings are built, how they are transformed and represented in the teaching practice.