Micropuncture Studies of Chloride Concentration and Osmotic Pressure in the Crayfish Antennal Gland*

Open Access
Publisher Website
Google Scholar
Abstract
1. Chloride concentration and freezing-point depression ( =osmotic pressure) have been measured on samples of urine obtained from various parts of the crayfish antennal gland by micropuncture. 2. The chloride concentration of the urine is significantly below that of the blood in all parts of the antennal gland, but a marked drop is not seen until the distal tubule is reached. 3. The urine becomes progressively hypo-osmotic to the blood in the labyrinth, distal tubule and bladder. In the coelomosac, it is iso-osmotic; possible reasons for this are discussed. 4. Chloride concentration and osmotic pressure are lower in urine taken from the nephropore than in urine taken from the distal tubule near the place where it joins the bladder. This suggests that the bladder is in part responsible for the production of hypotonic urine. 5. The results of the present study are discussed in relation to the theory that filtration (in the limited sense discussed by Riegel & Kirschner, 1960) is the mechanism by which primary urine is formed in the crayfish antennal gland.