Abstract: The gutta-containing structure in the cortex of a stem of Eucommia ulmoides is a filamentous, secretory cell. Observation of thin sections revealed that when the procambium of a stem differentiated into the earliest sieve elenents of protophloem, the initials cells appeared as daughter cells originated from a longitudinally equational or unequational divisions, or from the terminal cell formed by several transverse divisions of some cortical ground meristematic cells. Before the ceils of the cortical ground'meristem ceased to divide, the initial cells, in an arbitrary position of origin, develops continuously. These initial cells were able to be distinguished from the surrounding cells by their large length/width ratio, the presence of elliptical nuclei and dense cytoplasm, etc. Later, both ends of the initial cells extended rapidly through intrusive growth, forming the very long, thin and filamentous unicell with two dilated terminations. During development, the gutta particles were gradually synthesized and accumulated in the cytoplasm, where as the organelles degenerated progressively. In the muture gutta-containing cell, the cell cavity was filled with gutta particles, the nucleus as well as other organelles was disintegrated leaving an intact fibrous cell wall.

Key words: Eucommia ulmoides Oliv., Gutta-containing cell, Initiation, Development