File:Rugh 056.jpg

Surface changes of the Frog's Egg at the time of Fertilization

(A) Sperm contact, entrance generally in the animal hemisphere.

(B) Second polar body emerges, the sperm penetrates the cortex, and the surface pigment recedes toward the sperm entrance point forming the gray crescent. Lateral view.

(C) Dorsal view showing the sperm penetration path, centrally located polar bodies and egg nucleus, and (arrows) pigment recession to form the gray crescent.

(D) Rotation of the sperm head and middle piece 180° as it veers from the penetration path to the copulation path, in line with the egg nucleus.

(E) First division spindle forming at right angles to the copulation path. Since the copulation and penetration paths are not in the same plane, the cleavage furrow does not cut through the middle of the gray crescent.

(F) When the penetration and copulation paths are continuous and in essentially a straight line, the first cleavage furrow will bisect the gray crescent.

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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 28) Embryology Rugh 056.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Rugh_056.jpg

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