DIMENSIONS AND ULTRASTRUCTURE OF TOADFISH GILLS

¹ Research Unit for Comparative Animal Respiration, The University, Bristol BS8 1UG, England
² Department of Zoology, Duke University, Durham, North Carolina 27706

1. This analysis of the measurement from the gills of about 60 toadfish using log/log transformation has shown that the gill area and its constituent parts increases with body weight as follows:

Total area (mm²) = 560.7 W^0.79 Total filament length(mm) = 302.1 W^0.485 Secondary lamellae/mm on one side of filament = 15.99 W^-0.075 Average bilateral area of a secondary lamella (mm²) = 0.06 W^0.372

2. A comparison with the corresponding data for other fish, particularly tunas, shows differences in the values of these relationships and confirms the general conclusion that the gills of more sluggish fish have a smaller number of larger secondary lamellae and relatively wider spaces through which the water flows.

3. An electron microscope study of the toadfish secondary lamella has shown the same basic structure as in other teleost fish but the collagen layer of the basement membrane is especially thick. Also noticeable are distinct lymphoid spaces between the two epithelial layers and the presence of stages in the development of cells concerned with the protection of these layers. The water/blood barrier therefore comprises the following layers in certain regions: (1) outer epithelial layer, (2) lymphoid spaces, (3) inner epithelial layer, (4) basal lamina, composed of outer clear and inner fine fibrous layers, (5) collagen layer, (6) pillar cell flange.

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