Buckland-Nicks J A, Chia F S
Cell Tissue Res. 1976 Aug 10;170(4):455-75. doi: 10.1007/BF00361704.
The fine structure of the spermatogonium, spermatocyte and spermatid of a marine snail, Littorina sitkana is described. The ring centriole (annulus) is formed from the distal centriole and it migrates to the base of the mitochondrial region where it lies in a joint-like structure which is formed by an area of invaginated plasma membrane. The distal and proximal centrioles are at first perpendicular to each other but the proximal centriole rotates to a position coaxial with the distal centriole and fuses with it. The peripheral doublet fibers are continuous between the two centrioles but the central fibers originate only in the distal centriole. The acrosome differentiates from the proacrosomal granule which is derived from a Golgi body. Microtubules, present at this stage, may assist acrosomal formation. Chromatin condensation begins with the formation of fibrous strands, then to lamellar plates which become folded and later twisted around the flagellar shaft. In the final stages the lamellae appear in cross section as concentric rings which eventually fuse to form a homogeneously dense nuclear tube.
描述了一种海蜗牛——西特卡滨螺精原细胞、精母细胞和精子细胞的精细结构。环形中心粒（环）由远端中心粒形成，并迁移到线粒体区域的基部，位于由内陷质膜区域形成的关节状结构中。远端和近端中心粒最初相互垂直，但近端中心粒旋转到与远端中心粒同轴的位置并与之融合。两个中心粒之间的外周双联体纤维是连续的，但中央纤维仅起源于远端中心粒。顶体由源自高尔基体的前顶体颗粒分化而来。此时存在的微管可能有助于顶体形成。染色质浓缩始于纤维状链的形成，然后形成层状板，层状板折叠并随后围绕鞭毛轴扭曲。在最后阶段，层状板在横切面上呈现为同心环，最终融合形成均匀致密的核管。
