Phragmoplast

Phragmoplast and cell plate formation in a plant cell during cytokinesis . The cell plate begins to grow from the center to the cell wall . When a cell plate reaches it, cytokinesis occurs and the cell is divided into two daughter cells . After this, the cell plate by biochemical transformations becomes the cell wall of a new cell.

Phragmoplast (from the Greek. Φραγμος - septum and Greek. Πλαστος - fashioned, decorated ^[1] ) is the specific structure of a plant cell that forms during late cytokinesis . It is a system of short microtubules , microfilaments, and elements of the endoplasmic reticulum (EPR), collecting perpendicular to the plane of cell division in the anaphase and telophase of mitosis . A pectin cell plate is laid in the fragmoplast, which divides the mother cell in two ^[1] .

Initially, the fragmoplast has a cylindrical shape and is formed from a former fission spindle between two daughter nuclei , until a nuclear membrane is gathered around them again. The cell plate is first formed as a disk-like structure between the two halves of the fragmoplast. While new elements of the cell plate are added to its growing ends, the microtubules of the fragmoplast leave the center and move to the ends of the growing plate. So these two structures grow together until they reach the plasma membrane of the dividing cell. If a fragmosome was present in the cell, then the fragmoplast and cell plate will grow through the space previously occupied by the fragmosome. They will reach the cell wall of the dividing cell exactly in the places previously occupied by the preprophase tape .

Microtubules and actin filamentous fragmoplast filaments direct vesicles and cell wall material to the growing ends of the cell plate. Perhaps actin filaments also direct the fragmoplast to the position occupied by the former preprophase ribbon of the plant cell. While the cell plate grows, it captures segments of smooth EPR , which then provide a connection through plasmodesm between two daughter cells.

Phragmoplast can be observed only in higher plants (i.e. mosses and vascular plants ) and in some algae, in particular, from the harophyte department. Other algae during cytokinesis use another complex of microtubules - phycoplast ^{[2] [3]} .