Surfaces of Mammalian Spermatozoa as Revealed in Platinum Replicas

Abstract

Modification of available techniques for making platinum replicas of spermatozoa made it possible to visualize configurations of mitochondria, the outer surface of acrosomal membranes, the post-acrosomal region of sperm heads, and the exterior face of fibrous sheaths. Spermatozoa taken from the cauda epididymis of several mammalian species were treated 5 to 15 min with hypotonic (0.25 strength) Hank's BSS or 0.1% Triton X-100 in saline. After 1 hr. fixation in 3% collidine-buffered glutaraldehyde, spermatozoa were pelleted by slow speed centrifugation, and resuspended in water. Spermatozoa were then pelleted, resuspended in 0.5 ml of water, and allowed to settle onto a coverslip, pretreated by immersion in a 2 mg/ml solution of poly-L-lysine for 30 min and brief washing in water. Coverslips with attached sperm were dehydrated through graded alcohols to acetone and subjected to critical-point drying Replicas were made with an Edwards 306 coater by shadowing at 40° with platinum and 90° with carbon.