FLAGELLAR STRUCTURE IN NORMAL HUMAN SPERMATOZOA AND IN SPERMATOZOA THAT LACK DYNEIN ARMS

Human sperm flagella were analyzed by electron microscopy and computer averaging in order to characterize normal flagella and to detect diff erences between normal and mutated spermatozoa. The A-tubules of norma l spermatozoa were seen to have 13 protofilaments and a lumen containi ng a 'pentagon' and a 'sickte'. The incomplete B-tubule was seen to ha ve 10 protofilaments with an angular separation such that a complete c ircle would have 16 protofilaments. A thin '11th filament' is located at the inner border between A- and B-tubules and, in the centriole, al so between B- and C-tubules. The tail end piece has 18 microtubules of a conventional appearance. We conclude that the 9 axonemal doublets s plit distally into 2 microtubules and that normal microtubules with 13 protofilaments can grow from the incomplete B-tubules. The cell membr ane in the end piece has a glycocalyx with regular periodicity. Sperma tozoa from a man suffering from the immotile-cilia syndrome was also a nalyzed. His sperm flagella were seen to be abnormal in that the dynei n arms are lacking, and, in that the sickle is incomplete. In other re spects his immotile spermatozoa were normal; spokes and central projec tions have the same appearance as in normal spermatozoa.