Pölynrakenne

Pölynrakenne refers to the structure and composition of pollen grains, which are reproductive cells produced by male reproductive organs of flowering plants. Pollen grains are typically microscopic, ranging from 10 to 100 micrometers in diameter, and are composed of several distinct parts. The outer layer of the pollen grain is the exine, which is often covered in spines or other structures that aid in its dispersal. The exine is composed of sporopollenin, a highly resistant and durable substance that protects the pollen grain during its journey from the plant to the stigma of another flower.

Inside the exine is the intine, a thin layer of cellulose that surrounds the pollen grain's contents. The contents of the pollen grain are composed of two vegetative cells and two generative cells. The vegetative cells are responsible for the growth of the pollen tube, which delivers the sperm cells to the female gametophyte within the ovule. The generative cells fuse to form two sperm cells, which are necessary for fertilization.

Pölynrakenne plays a crucial role in plant reproduction, as it facilitates the transfer of genetic material from the male reproductive organ to the female reproductive organ. The structure and composition of pollen grains vary among different plant species, reflecting the diverse adaptations and strategies employed by plants to ensure successful reproduction.