REFRIGERATED STORAGE AND CRYOPRESERVATION OF BLACK DRUM (POGONIAS-CROMIS) SPERMATOZOA

Procedures were developed for the collection, refrigerated storage and cryopreservation of black drum spermatozoa. Sperm samples were collec ted by removing and slicing the testis, and suspending the spermatozoa in Hanks' balanced salt solution (HBSS) at 200 mOsm/kg. Threshold act ivation (10%) of black drum spermatozoa occurred at 370 mOsm/kg, and c omplete activation occurred at 580 mOsm/kg in HBSS. Sperm cells activa ted in artificial seawater had higher motility than those activated in HBSS at osmolalities from 350 to 500 mOsm/kg. Spermatozoa stored at 4 degrees C in HBSS or artificial seawater at osmolalities from 202 to 290 mOsm/kg retained motility longer than did those stored at other os molalities. Dilution rate had no effect on sperm storage time at 4 deg rees C. Four chemicals were evaluated as cryoprotectants: dimethyl sul foxide (DMSO), n,n-dimethyl acetamide (DMA), methanol, and glycerol. G lycerol and DMA at concentrations of 10% significantly reduced motilit y within 52 min. Spermatozoa were cryopreserved at 3 freezing rates (- 27, -30, or -45 degrees C/min) in a nitrogen vapor shipping dewar or a computer-controlled freezer. Spermatozoa frozen using 10% DMSO had th e highest post-thaw motility at a freezing rate of -27 or -30 degrees C/min. Spermatozoa frozen using 5% glycerol, 5% DMSO, or 10% DMSO had the highest post-thaw motility at a freezing rate of -45 degrees C/min . (C) 1997 by Elsevier Science Inc.