[The ultrastructure of bull sperm membranes prepared by freeze etching]

Intramembraneous particles represent protein components of the membrane. It is assumed that their number and distribution are in correlation with the level of the metabolic activity of membranes. In the cytoplasmic membrane in the postacrosomal region (PF) near the posterior ring the particles are arranged in form of palisade rows. In the remaining membranes of the head, irregularly distributed particles were observed. Their number at individual places varied. Their size was not equal either. The areas without particles were also found out. The particles in the cytoplasmic membrane of the flagellum (PF) formed clusters and they had circumferential orientation in the direction of mitochondria. At the place of the annulus the number of particles increased. The distribution of particles was irregular in the cytoplasmic membrane of the main section.