Objective This study is to reveal the changes of cellular structure, composition and function of secondary vascular tissue in Pinus massoniana during development.

MethodsThe change of morphology, structure, lignin and cellulose in the vascular tissue of P. massoniana were studied by histochemical analysis and cell segregation.

ResultsThe vascular cambium gradually enriched cellulose when it differentiated into new phloem and xylem. During the development of phloem, the sieve cells were deformed and lignified, and the proportion of cellulose in phloem decreased. During the development of xylem tracheids from early wood to late wood, the diameter of striated pores decreased, the number of striated pores decreased, the lignification degree of secondary wall increased, the cell lumen area decreased, the proportion of cellulose content decreased, and the choroidal and radial walls thickened.

Conclusion The cellular composition and structure of secondary vascular tissues change regularly with development. The intracellular and intercellular transport capacity of xylem cells decrease, while the mechanical strength increases. The secondary phloem loses its ability to transport and its mechanical strength increases.