Detailed histological studies of the brains of 23 species of Lepidoptora reveal a remarkable uniformity in the disposition, multiplicity of neurosecretery cells, and in the number of most types of cells. The recognition of A-, B-, C- and D-calls is based upon tho paraldehyde fuchsin staining technique. These maajor categories are further divided, to give a total of 10 types of cells. In all species neuresecretery cells are confined to medial and lateral groups of the pars intercerebralis. with the exception of medial B-cells, all of the neurosocretery cells that occur in the adult become differentiated during the second larval instar. The cycles of secretion and increases in volume of the cytoplasm are estimated in 6 types Of cells and correlated with physiological processes. In adults, activity Of the neurosecretory cells was studied in the short-living saturniid moth, Philosamia cynthia ricini, and compared with the comparatively long-living noctuid, Trip-haena pronuba. Circadian cycles of secretion in the medial Al-and A2-cells are correlated with diuresis and flight activity respectively. A detailed histochemical analysis provides evidence in support of the assumption that inclusions in the various types of neuresecretery cells differ in chemical composition. It is suggested that the inclusions of A- and C-cells are glyoproteins and that the B-cell inclusions are proteins. There is histochemical evidence that A2-cells also contain 5-hydroxytryptamine. Factors affecting activity were analysed, using an actograph designed to record the insects in flight. An endogenous flight rhythm was demonstrated in nocturnal moths. Thu effect of ablating neuresocretery cells and areas of the brain was studied, and a hypothesis of hormonal control of flight activity is put forward. The role of 5-hydroxytryptamine in the initiation and maintenance of the circation flight rhythm is discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:623046 |
| Date | January 1968 |
| Creators | Hinks, Christopher Frederick |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/15875 |
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