title: On the presence of bridges linking the inner and outer acrosomal membranes of boar spermatozoa.
abstract: The presence of structures bridging the inner and outer acrosomal membranes of the equatorial segment of boar spermatozoa was clearly demonstrated in cells that have undergone a variety of treatment procedures to displace the electron-dense contents of the acrosome. En-face sections show bridges to be punctate and not linearly extensive as might be suggested by sections perpendicular to the flat plane of the head. About 4.5 x 10(5) bridges, each measuring 7 nm across and spaced 7 nm apart, are arrayed hexagonally in the equatorial segment, but bridges are not present within the principal segment of the acrosome. Short-term treatment with trypsin partially digests the bridges, but does not disrupt the spacing or strict parallel configuration of equatorial segment membranes. However, short-term treatment with pronase digests most bridges and effectively disrupts the typical configuration of the equatorial segment. Freeze-fracture of the cytoplasmic face of the acrosomal membranes of the equatorial segment reveals a pattern throughout the phospholipid layer of the membrane which is similar to the pattern of bridges present in en-face thin sections of the equatorial segments. The data suggest that numerous bridges link the inner and outer acrosomal membranes of the equatorial segment of the acrosome and they play a major, if not an exclusive, role in maintaining the close spacing and parallel arrangement of the membranes in this portion of the acrosome.
mesh_terms: D000177:Acrosome / Q000502:physiology / Q000648:ultrastructure*; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010447:Peptide Hydrolases / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D013094:Spermatozoa / Q000648:ultrastructure*; D013552:Swine / Q000033:anatomy & histology*
chemical_list: D011092:Polyethylene Glycols; D010447:Peptide Hydrolases