The Function of the Basal Filaments in the Parietal Layer of Bowman's Capsule
A number of cell types in the nephron have been known for some time to contain basally located filaments demonstrable by a variety of both light and electron microscopic techniques.]t has been proposed that these filaments may provide a contractile mechanism which would have implications for the control of renal function. One site in which these filaments have been observed is in the parietal layer of Bowman's capsule. The present study was designed to see if contraction of this layer of cells could be demonstrated and if so whether the basal filaments appeared to play a role in the process. Renal cortical tissue was fixed both in vivo and in vitro in the presence and absence of histamine, adrenaline, and acetylcholine and examined by conventional electron microscopic techniques. Basal folding of the cell membrane was observed particularly in the adrenaline-treated tissue and was interpreted as reflecting a conformational change in the cell such as might be expected with contraction. The relationship of this folding, however, to the arrangement of the basal filaments was such as to suggest that contraction of the filaments was not responsible for the folding observed. Alternative roles for the fibrils either as a structural framework or as a component in an attachment mechanism of the cells to the underlying basement membrane were therefore proposed.