The aquatic carnivorous plant Aldrovanda vesiculosa (Droseraceae) exhibits altered developmental stages in male gametophyte.

Aldrovanda vesiculosa (Droseraceae) is a rare aquatic carnivorous plant, distributed in Europe, Asia, Africa, and Australia. Aldrovanda populations can flower prolifically under favourable conditions, but seed set is very limited. We studied the structure of Aldrovanda pollen collected from flowers in different developmental stages (opened and non-opened anthers) from both European and Australian populations to elucidate pollination traits and the basis of poor seed set on the basis of microscopic observation of pollen and anther structure. Microscopic analyses of Aldrovanda pollen showed that this plant has pollen arranged in tetrads like other species in the Droseraceae family. In hydrated pollen, cytoplasmic protrusions originate from pores located along the equatorial wall of monads, and can develop into pollen tubes. Interestingly, pollen development from microspores occurs in open anthers, suggesting a delay of the developmental stages. In addition, pollen development displays altered sperm cell formation and precocious pollen germination. Precocious germination may characterize recalcitrant pollen, which naturally do not undergo dehydration before anthesis and remain partially hydrated, particularly in aquatic and wetland plants. These alterations of male gametophyte development could affect fertilization processes, and be the reason for the low reproductive capability of Aldrovanda observed both in the field and in cultures. Generally, reduced pollen longevity and very quick germination are considered an adaptation to aquatic or wet environments.

Effect of submucosal injection of dexamethasone on postoperative discomfort after third molar surgery: a prospective study.

PURPOSE: The purpose of this study was to evaluate the effect of submucosal administration of dexamethasone sodium phosphate on discomfort after mandibular third molar surgery. PATIENTS AND METHODS: Sixty-one consecutive patients requiring surgical removal of a single mandibular impacted third molar under local anesthesia were randomly placed into 3 groups. After the onset of local anesthesia, the experimental groups received dexamethasone at 2 different doses (4 or 8 mg) as submucosal injection, and the control group received no drug. Standardized surgical and analgesic protocols were followed. Maximum interincisal distance and facial contours were measured at baseline and at postsurgery days 2 and 7. Pain was objectively measured by counting the number of analgesic tablets required. The patients' perception of the severity of symptoms was assessed with a follow-up questionnaire (PoSSe scale). RESULTS: On the second postoperative day, facial edema showed a statistically significant reduction in both dexamethasone 4-mg and dexamethasone 8-mg groups compared with the control group, but no statistically significant differences were observed between the 2 dosage regimens of dexamethasone. By contrast, there was no statistically significant difference between all groups when postoperative swelling was evaluated at day 7 (P > .50). The treatment group had a limited and nonsignificant effect on pain and trismus when compared with the control group at the 2 times of evaluation. CONCLUSIONS: Parenteral use of dexamethasone 4 mg, given as an intraoral injection at the time of surgery, is effective in the prevention of postoperative edema. Increasing the dose to 8 mg provides no further benefit.