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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 133 (1972), S. 147-162 
    ISSN: 1432-0878
    Keywords: Lymph node (dog) ; Reticulum ; Pulp ; Ultraarchitecture ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The perfused large mesenteric lymph node of the dog was observed under the scanning electron microscope. The lymph sinus contains reticulum cells which mostly are two-dimensionally formed stellate plates oriented in a uniform direction. Large round macrophages are loosely fixed by the reticulum cell processes. No intermediate type between both cells has been observed. Macrophages having a few long tentacle-like projections are densely covered by clubbed cytoplasmic processes. Smaller round cells, probably plasma cells and lymphocytes also remained in the sinus. The pulp of the node is built up by reticulum cells, much smaller than those in the sinus, and by densely packed round cells including a few macrophages. The trabeculae and the reticulum of the nodal parenchyme form a continuous structure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 48 (2000), S. 276-284 
    ISSN: 1432-0762
    Keywords: Key words Attini ; CAP-PCR DNA fingerprinting ; Polyandry ; Polyethism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The mating frequency of queens was estimated for eight attine ant species, Myrmicocrypta ednaella, Apterostigma mayri, Cyphomyrmex costatus, C. rimosus (four lower attines), Trachymyrmex isthmicus, Serico-myrmex amabalis, Acromyrmex octospinosus and Atta colombica (four higher attines), and correlated to colony size, worker polyethism, and sex ratio. Mating frequency was calculated from within-colony relatedness estimated by CAP-PCR DNA fingerprinting. Most queens of lower attines and T. isthmicus mated with only one male, while those of the three higher attines mated with multiple males. Mating frequency was positively correlated with colony size. Polyethism among workers was dependent on worker age in lower attines but on body size in higher attines, suggesting some correlation between mating frequency (i.e., within-colony gene diversity) and caste complexity. The sex ratio was biased toward females in species where the mating frequency equaled one, but toward males in species where the mating frequency was greater than two. Changing in nest site from ground surface to deep underground may have facilitated the evolution of large colony size in Attini, and this may have resulted in the evolution of polyandry (a queen mates with multiple males). With the evolution of polyandry in higher attines, Atta and Acromyrmex in particular have generated high genetic diversity within their colonies and complex social structures.
    Type of Medium: Electronic Resource
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