SURVIVAL OF OVULATED OOCYTES OF THE EUROPEAN CATFISH (SILURUS-GLANIS)AFTER IN-VIVO AND IN-VITRO STORAGE OR EXPOSURE TO SALINE SOLUTIONS AND URINE

Survival of Silurus glanis ovulated oocytes (oval measured by the capa city of normal development i.e. percentage of normal and abnormal hatc hed larvae after in vivo and in vitro storage and exposure to sperm ac tivating or immobilizing solutions and urine was studied. In the case of ovulated oocytes left in the ovaries, total hatching and abnormal h atched larvae (in % of hatching) were respectively 74 and 8.2% immedia tely after ovulation, 77 and 8.6% after 2 h, 54 and 18% after 4 h, and 38 and 50% after 6 h of storage. Four and 6 h stay of ovulated oocyte s in ovaries resulted in a significant increase of abnormal hatched la rvae (p<0.01). For the ova stored in vitro, the capacity to undertake a full embryonic development after fertilization was not significantly changed either after 8.5 h at 19 degrees C or 3.5 h at 25 degrees C; there was no ova survival at all after 3.5 h storage at 8 degrees C, 1 2 h at 19 degrees C and 8.5 h at 25 degrees C. There was a significant increase of abnormal larvae after 3.5 h at 25 degrees C (74%, p<0.001 ) and after 8.5 h at 19 degrees C (37%, p<0.05). Exposure of non insem inated ova to water buffered to pH 7.0 (5 mM Tris-HCl) to sperm activa ting solution (17 or 41 mM NaCl, 5 mM Tris-HCl, pH 8.0) or to immobili zing solution (200 mM NaCl, 30 mM Tris-HCl, pH 7.0) resulted in a regu lar and rapid decrease of their capacity of development; this was 10% of normal hatched larvae within 4 min in water, and within 6-8 min in the NaCl solutions. A similar situation was observed after exposure to urine with a loss of embryonic development of 30% within 3 min. These results indicate that all steps of the whole procedure of gamete coll ection and artificial insemination should be carried out rapidly as so on as possible after ovulation.