The experiments were carried out on Protopterus aethiopicus in East Africa. They were: the injection of commercial adrenocorticotrophic hormone, hypophysectomy, administration of ACTH after hypophysectomy, artificially induced aestivation, and artificially induced ‘stress’.
The two elements of the lipid tissue show differing reactions to the experiments carried out. The large lipid cells appear to be under direct pituitary control: active secretion follows ACTH administration, hypophysectomy leads to a blocking of secretion. After ‘stress’ and hypophysectomy the small lipid cells develop sudanophil inclusions which are positive to the histochemical tests for steroids. This does not occur after ACTH administration.
The phagocytes of the endothelial system take part in the transfer of material within the peri-renal tissue; this is shown by their cytology after ACTH administration and ‘stress’. Evidence from these experiments indicates that the round pigment cells characteristic of the normal animal are syncytial structures formed by the fusion of phagocytic cells containing pigment and remains of large lipid cells.
The steroid tissue shows little change in these experiments other than a decrease in the amount of steroid material after ACTH, and a more intense staining of the mitochondria after hypophysectomy.
The number of eosinophil leucocytes increases as the result of ACTH administration.
The round cell nodules showed no detectable changes in these experiments.
Experimental alteration of the phenotype of animal cells in vivo
