Local action of thyroxin on amphibian metamorphosis. II. Development of the eyelids, nictitating membrane, cornea, and extrinsic ocular muscles in Rana pipiens larvae effected by thyroxin-cholesterol implants

1953 ◽  
Vol 122 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Jane Couffer Kaltenbach
Keyword(s):  
Rana Pipiens ◽  
Local Action ◽  
Nictitating Membrane ◽  
Amphibian Metamorphosis

Ultrastructure of the Intestinal Absorptive Cells of Fed and Fasted Tadpoles

1970 ◽  
Vol 28 ◽  
pp. 86-87
Author(s):  
Robert Giaquinta ◽  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Small Intestine ◽  
Fine Structure ◽  
Osmium Tetroxide ◽  
Rana Pipiens ◽  
Ultrastructural Changes ◽  
Amphibian Metamorphosis ◽  
Absorptive Cells ◽  
Food Absorption ◽  
Tissue Specimens

The ultrastructural changes that occur in the intestinal absorptive cells during amphibian metamorphosis have been reported (Bonneville, 1963). These changes accompany a change in diet (from an herbivorous to a carnivorous state) during metamorphosis. Little information is available, however, on the ultrastructural changes in the absorptive cells of amphibians in relation to the state of feeding. This report describes the differences in the fine structure of these cells in the tadpole stage of Rana pipiens during periods of food absorption and fasting.Rana pipiens at tadpole stages were fed an herbivorous diet, and after a period of 48 hr, the animal was dissected and segments of the small intestine were collected for electron microscopy. A second group of tadpoles was fasted for 7 days, and segments of the small intestine were collected. The tissue specimens were immersed in phosphate-buffered glutaraldehyde (3%) for 1 hr at 4C and postfixed with phosphate-buffered osmium tetroxide (2%) for 1 hr at 4C.

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