File:Rugh 169.jpg

Stages in the metamorphosis of Rana pipiens

(Stage I) The oral sucker elevations have completely disappeared. Four rows of labial teeth are present, one pre-oral and three post-oral. Chromatophores have appeared and become numerous on the dorsal and lateral surfaces, and extend progressively ventrad. The limb bud is visible as a faintly circumscribed elevation in the groove between the base of the tail and the belly wall. The height of the elevation is less than half the diameter of the disk.

{Stage II) The height of the limb bud elevation (i.e., the length of the bud) is equal to half of its diameter. The first row of post-oral labial teeth is usually at the middle to form a pair of crescents. On the dorsal surface of the head the lateral line system is becoming conspicuous as pigment-free lines, especially in darkly pigmented individuals. The melanophore patches covering the gill region on either side usually meet in a narrow band ventral to the heart.

(Stage III) The length of the limb bud is equal to its diameter, and it continues to grow both in length and diameter at an approximately equal rate. This stage is relatively long in duration. (Stage IV) The length of the limb bud is equal to one and a half times its diameter.

(Stage V) The length of the limb bud is twice its diameter. The distal half of the bud is bent ventrad. There is no flattening of the tip. (Continued on facing page.)

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Reference

Rugh R. Book - The Frog Its Reproduction and Development. (1951) The Blakiston Company.

Cite this page: Hill, M.A. (2024, April 27) Embryology Rugh 169.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Rugh_169.jpg

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