Search results
Results from the WOW.Com Content Network
Oscar Hertwig first achieved artificial parthenogenesis in frogs in 1911, using eggs fertilized by irradiated sperm. [1] The radiation destroyed the DNA within the sperm, but nearly normal embryos were still produced. Gunther Hertwig repeated this experiment in 1924, using crosses between different frogs. [1]
The first frog egg extract was reported in 1983 by Lohka and Masui. [1] This pioneering work used eggs of the Northern leopard frog Rana pipiens to prepare an extract. Later, the same procedure was applied to eggs of Xenopus laevis, becoming popular for studying cell cycle progression and cell cycle-dependent cellular events. [2]
This frog has been observed between 10 and 865 meters above sea level, near rocky-bottomed streams. The frog has been observed in secondary forest, so scientists infer that it may tolerate some habitat disturbance. [1] The female frog lays eggs in leaf litter. After the eggs hatch, the male frog carries the tadpoles streams. [1]
The nearly 400 northern leopard frogs were collected as eggs by the Washington State Department of Fish and Wildlife and raised from tadpoles by Northwest Trek Wildlife Park and Oregon zoo staff ...
Closed ecological systems or contained ecological systems (CES) are ecosystems that do not rely on matter exchange with any part outside the system. The term is most often used to describe small, man-made ecosystems. Such systems can potentially serve as a life-support system or space habitats. [1]
After mating, females release up to 500 eggs during spawning [7] in still waters. [citation needed] The water holding frog's eggs are not held together by a frothy mass so they may attach in clumps to surrounding vegetation or spread in a thin film on the surface, [7] thus ensuring adequate oxygen in warm waters suffering from oxygen depletion ...
The crawfish frog, endangered in the Hoosier State, is back following an effort led by the Indiana Department of Natural Resources and Angel Mounds. History of crawfish frogs at Angel Mounds
Reptile eggs, bird eggs, and monotreme eggs are laid out of water and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell.