A freeze-fracture study on epididymal and ejaculate spermatozoa of the monkey (Macaca fascicularis).

Spermatozoa from four epididymal regions and from the ejaculate of the monkey, Macaca fascicularis, always present the same particle organization for a given sample. The plasmalemma contains homogeneously distributed, 7-8 nm size, PF-face, particles throughout the head, midpiece and principal piece. A unique, particle arrangement occurs in the plasmalemmal, PF-face in spermatozoa from the proximal levels of the body of the epididymis only. Square arrays of 4-6 nm size, PF-face plasmalemmal particles occur in this region of the epididymis at the peripheral edge of the spermatozoon acrosomal region only. Throughout other regions of the epididymis the plasmalemma contains only the homogeneously distributed, 7-8 nm size, PF-face particles. Ejaculate spermatozoa exhibit a similar particle organization to that of spermatozoa found in the distal portions of the epididymis. However, ejaculate spermatozoa of one animal from the eight used in this study exhibited a series of 7-8 nm size, linearly arranged, plasmalemmal, PF-face particles situated just proximal to the striated ring. This array of particles continued further rostral on the lateral aspect than on the flattened medial aspect of the spermatozoon. Spermatozoa from the tail of the epididymis and from ejaculates of the other seven animals lacked such specialization. The above data is discussed in terms of the population of particles generally, the significance of the presence of linearly arranged particles proximal to the striated ring, and the possible significance of the square arrays of particles present transiently in one region of the epididymis only. A correlation is made between these square arrays and similarly arrayed particles found in rat and boar epididymal spermatozoa.