Partectum

A partectum is a bulbous chamber on the inside of the valvocopula, found only in the genus Mastogloia. The plural is partecta. Partecta are usually arranged in a row on each side of the valvocopula, together forming the partectal ring.

The partecta secrete mucilage to the outside of the diatom cell through the partectal pores in the wall of the valvocopula. These pores are connected to the partecta by the partectal ducts.

Alternative Terms

chamber: A synonym for partectum.
locule: An alternate term for partectum, used in some of the older literature (Stoermer et al., 1964).

Citations

Round, F.E., Crawford, R.M. and Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
Stoermer, E.F., Pankratz, H.S. and Drum, R.W. (1964) The fine structure of Mastogloia grevillei Wm. Smith Protoplasma 59: 1-13

Partectum2 — Light micrographs of *Mastogloia smithii*. On the left, a high level of focus showing the valve face. On the right, a deeper level of focus revealing the valvocopula, with a row of partecta on each side.

Partectum — Light micrographs of the valvocopula of *M. pumila*. On the left, the entire valvocopula. On the right, several partecta, with one partectum marked by an arrow.