gemmule


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gemmule

 [jem´ūl]
1. a reproductive bud, the immediate product of gemmation.
2. any of the little spinelike processes on the dendrites of a nerve cell.

gem·mule

(jem'yūl),
1. A small bud that projects from the parent cell, and finally becomes detached, forming a cell of a new generation.
2. Synonym(s): dendritic spines
[L. gemmula, dim. of gemma, bud]

gemmule

/gem·mule/ (jem´ūl)
1. a reproductive bud; the immediate product of gemmation.
2. one of the many little spinelike processes on the dendrites of a neuron.

gemmule

(jĕm′yo͞ol)
n.
1. A small gemma or similar structure, especially a reproductive structure in certain sponges that remains dormant for some time and later develops into a new individual.
2. A hypothetical particle in the theory of pangenesis, postulated to be produced by cells and to be responsible for transmitting traits from parent to offspring.

gem′mu·lif′er·ous (jĕm′yo͞o-lĭf′ər-əs) adj.

gemmule

See gemma.

gem·mule

(jem'yūl)
1. A small bud that projects from the parent cell, and finally becomes detached, forming a cell of a new generation.
2. Synonym(s): dendritic spines.
[L. gemmula, dim. of gemma, bud]

gemmule

a bud formed in sponges as an internal group of cells that gives rise to a new sponge after overwintering (in freshwater forms) and the decay of the parent.

gemmule

1. a reproductive bud; the immediate product of gemmation.
2. any of the little spinelike processes on the dendrites of a nerve cell.
References in periodicals archive ?
Diapausing gemmules were collected from Stony Brook in South Hadley, Massachusetts, in late September of 1993 and maintained at 4 [degrees] C until early October when calorimetry was performed (storage for 2 weeks at 4 [degrees] C is insufficient time to break diapause).
Experiments were initiated by filtering vernalized gemmules from the 4 [degrees] C storage water and placing them into 20 [degrees] C stream water that was continuously bubbled with air.
The influence of antibiotics (50 mg/l each of penicillin and streptomycin) on the heat dissipation was evaluated by exposing gemmules for 5 h to perfusion with nitrogen-saturated medium and then switching to the same nitrogen-saturated medium containing antibiotics.
Indeed, the changes in the two carbohydrates - measured as micromoles per gram of fresh weight of gemmule tissue ([micro]mol/gfw) - balance one another very closely: sorbitol decreases by 32 [micro]mol/gfw (from an average control value of 36 [micro]mol/gfw to an average steady-state level of 4 [micro]mol/gfw), and glycogen increases by 33 [micro]mol/gfw (from an average control value of 29 [micro]gfw to an average steady-state value of 62 [micro]mol/gfw).
Using histological techniques, De Vos (1977) has shown that glycogen is present in the early stages of gemmule formation and later disappears.
This is also a wonderful example of what Karl Popper (1963) called "conjecture and refutation," an intellectual process whereby ideas related to the underlying principle (in this case the gemmules of pangenesis) are proposed and then subjected to experiment in an attempt to reject them.
Darwin suggested that the gemmules were physical entities and that, as such, other scientists could look for them or for their effects.
Hatching of freshwater sponge gemmules after low temperature exposure: Ephydatia mulleri (Porifera: Spongillidae).
The Neotropical materials conform all the characteristics proposed for the genus but show consistent larger size of spicules and gemmules besides different shape and size of the sponges when compared to the Ethiopian species.
navicella found in the stomach contents of the fish Hipostomus regania (armored catfish) and Megalancystrus aculetatus (pineapple catfish) also originated from the region at the head of the lake and consisted of pieces of skeleton with gemmules, indicating detachment from firm crusts settled on rocky substrates.
The most interesting aspect of pangenesis (as shown in Figure 1) is that if some environmental stimulus caused a change in a body part, either by injury or by use and/or disuse, the "new" gemmules produced by that part would be different from those that would originally have developed there.
For instance, by assuming that gemmules could lie dormant for generations, "reversion" (the sudden reappearance of old traits) is easily explained.