Pollen cells. Sperm cells of Pinophyta and Gnetophyta are without flagella, and are carried by the pollen tube, while those of Cycadophyta and Ginkgophyta have many flagella. When placed on the stigma of a flowering plant, under favorable circumstances, a pollen grain puts forth a pollen tube, which grows down the tissue of the style to the ovary, and makes its way along the placenta, guided by projections or hairs, to the micropyle of an ovule. The nucleus of the tube cell has meanwhile passed into the tube, as does also the generative nucleus, which divides (if it hasn't already) to
Chemical Agent Resistant Coating Chemical Agent Resistant Coating Chemical Agent Resistant Coating is a paint commonly applied to military vehicles to provide protection against chemical and biological weapons. The surface of the paint is engineered to be easily decontaminated after exposure to chemical warfare and biological warfare agents. The paint is also resistant to damage and removal by decontaminating solutions. Two-component systems (e.g. epoxy or polyester-based) are often employed. This coating is described in MIL-DTL-53072E. As of 2018, the U.S. Army Research Laboratory (ARL) led research and development activity for CARC and was the approving authority of CARC products for the Department of Defense