HISTOPHYSIOLOGY OF GILL AND KIDNEY OF CRAB OCYPODE ALBICANS

¹ Edward Martin Biological Laboratories, Swarthmore College, Swarthmore, Peunsylvania, and Bermuda Biological Station, St. George's West, Bermuda

1. The fine structure of the gill and kidney of Ocypode albicans was examined for evidence of participation in the transfer of water and the chloride ion.

2. The epithelium of the gill lamellae was found to have the characteristics of a secreting epithelium. No other cells associated with the gill structure had either the position or morphology to be considered important in this function. The athrocytes of the gill stem probably do not participate in salt-water regulation, but are concerned principally with the removal of poorly diffusible ions from the blood stream. No mechanism of such removal can be interpreted from the present study.

3. The cells of the renal tubule of the kidney were found to have the characteristic brush border and mitochondrial picture associated with actively secreting or reabsorbing epithelia. Silver deposition following the Leschke test gave evidence that these cells are involved in the excretion of chloride, and may possibly also act to reabsorb chloride from the urine. The athrocytes of the kidney end-sac, like those of the gill stem, probably do not function in salt or water regulation. Materials accumulated within these cells are lost to the body when the cells break away and float free in the urine.

4. Absorption of salt from the environmental medium is accomplished by an energy-using mechanism in the lamellar cells. This isa constant function and is associated with the carbonic anhydrase mechanism working in the excretion of carbon dioxide. Excretion of salt by the renal tubule is probably also a constant function, although no evidence as to its possible mechanism is available. Reabsorption of salt at this location is a possibility; the triggering mechanism is probably a falling chloride concentration in the blood.