Specific glycoconjugates are present at the oolemma of the fertilization site in the egg of Discoglossus pictus (Anurans) and bind spermatozoa in an in vitro assay.

In the egg of the anuran Discoglossus pictus, the site of fertilization is restricted to the central portion of an animal hemisphere indentation (the dimple). Previous studies showed that the acrosome reaction of D. pictus sperm is triggered in the jelly, and yet sperm arrive at the dimple surface with the plasma membrane at an early stage of vesiculation.

A novel protein cross-reacting with antibodies against spectrin is localised in the nucleoli of amphibian oocytes.

Cytoskeletal proteins such as actin and myosin are important constituents of the nucleoplasm. Spectrin is an actin binding protein typically related to plasma membrane; recently, it has been found that it is widespread and forms distinct membrane protein domains in such organelles as the Golgi. In this paper, the large germinal vesicle of amphibian oocytes was chosen as a particularly suitable system to investigate the presence and location of spectrin in the nucleus.

Sperm-egg interaction in the painted frog (Discoglossus pictus): an ultrastructural study.

The ultrastructure of sperm changes and penetration in the egg was studied in the anuran Discoglossus pictus, whose sperm have an acrosome cap with a typical tip, the apical rod. The first stage of the sperm apical rod and acrosome reaction (AR) consists in vesiculation between the plasma membrane and the outer acrosome membrane. The two components of the acrosome cap are released in sequence.