Abstract
The sieve areas inWelwitschia are essentially similar to those of coniferous sieve cells, consisting of groups of plasmalemma-lined pores, which are joined in the middle of the wall by a median cavity. The median cavity contains membranes which apparently are connected with aggregates of endoplasmic reticulum bordering the sieve areas. The median cavity is formed through union of smaller median enlargements, the median nodules, each initially associated with a plasmodesma, during perforation of the young sieve area. Callose platelets are not associated with developing pores. All fully-developed pores were lined with callose. The sieve cells are connected with only one other cell type, the albuminous cell. On the sieve-cell side of the wall these connections are similar to sievearea pores, on the albuminous-cell side to plasmodesmata. These connections are also characterized by median enlargements.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.