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Title: Studies on the abdominal ganglia of the desert locust, Schistocerce gregaria (Forsal)
Author: Seabrook, W.
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1967
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The innervation of a pregenital abdominal segment and of the Genital and postsenital abdominal segments of Schistocerca gregaria is described in detail and compared with other orders of the Insecta. On the basis of innervation it is concluded that the Genital apparatus of the male is derived from the ninth abdominal segment, and that of the female from the eighth and ninth abdominal seaments. Histological studies of the anatomy are carried out on the seventh abdominal Ganglion and on the terminal Ganglionic mass. The organization of the commissures, longitudinal tracts and groups of neurocytes within the ganglia is described. The terminal ganglionic mass is shown to comprise the fused Ganglia of the eighth, ninth, tenth and cl.eventh abdominal segments and the effects of condensation on the component Ganglia arc discussed. Seventyfive neurone pathways are traced and described within the seventh abdominal Ganglion and one hundred and five within the terminal ganglionic mass. The abdominal Giant fibre system is investigated using histological and clectrophysiolosical techniques. The ventral connectives each contain four Giant fibres, unicellular in origin, which pass uninterrupted from the terminal ganglionic mass to the metathoracic ganglion. The Giant fibres are shown to synapse ipsilaterally and contralaterally with afferent neurones of the cereal nerve, and with afferent neurones of the ninth ventral nerve. Conduction velocities and. synaptic delays arc aeterminea. The absence of an evasion resonso upon cereal stimulation is related to the lack of functional synapses pith efferent neurones of the metathoracic lee nerve. Other functional pathways, elucidated by electroplAysiological observations, az'e described including; responses in the contralateral cereal nerve to cereal stimulation, and synchronized. efferent potentials in the genital nerves originating from within the terminal GanGlionic mass. In addition chemoreceptors are demonstrated on the cercus.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available