Longitudinal sections through (a) emu and (b) rhea spermatids. Note the prominence of the projections in the area immediately below the acrosome-nuclear shoulder in (a), but also at the base of the nucleus in (b) (encircled). (c) Oblique section of an emu spermatid demonstrating the typical lattice pattern (block arrow) formed by the projections. The nuclear chromatin (N) is in the form of coarse granules, indicating an earlier stage of spermatid development than that illustrated in (a) and (b). A series of cytoplasmic densities is apparent in the vicinity of the manchette microtubules (black arrow). Acrosome (A), nuclear membrane (white arrows). Bar = 0.5 μm.
du Plessis and Soley BMC Evolutionary Biology 2013 13:104 doi:10.1186/1471-2148-13-104