What are the morphology and division modes of spindle primitive cells and ray primitive cells?

(1) Spindle-shaped primitive cells are spindle-shaped in shape, and the number of cambium primitive cells increases due to proliferation and division. There are three main ways of splitting:

① Radial vertical division, that is, a spindle-shaped primitive cell divides vertically or nearly vertically into two cells, and the tangential growth of daughter cells broadens the section;

(2) Transverse and vertical division, that is, one side of spindle-shaped primitive cells divides into new cells, and its growth also widens the section;

(3) Quasi-transverse division, that is, spindle-shaped primitive cells divide obliquely and vertically, which is almost similar to transverse division. The two daughter cells are oblique and the tips are staggered. The upper part extends downward and the lower part extends upward, forming longitudinal invasive growth. As a result, the two daughter cells are juxtaposed.

(2) The proliferation and division of ray primitive cells are multiplied by the transformation of spindle primitive cells, which are cuboid in shape and usually have the following forms:

① Spindle-shaped primitive cells divide horizontally, that is, a part of them divide vertically among primitive cells to form ray primitive cells;

(2) A ray primitive cell was transversely divided near the top of spindle primitive cell;

③ Half spindle primitive cells split into single ray primitive cells;

④ Spindle primitive cells differentiated into single ray primitive cells;

⑤ Spindle primitive cells decreased and gradually shortened, forming ray primitive cells.

A ray primitive unit can be subdivided into a row of ray primitive units, and a single row of ray primitive units can be vertically divided into two rows, thus forming multiple rows; Double rows and columns of ray basic units can also be combined into wider ray basic units.