Development and fate of the membranous organelles in spermatozoa of Ancylostoma caninum.

During development membranous organelles first appeared in the primary spermatocytes of Ancylostoma. They were derived from the Golgi as two separate components. One component, an electron-dense spheroid, quickly fused with other newly-formed cup-shaped, membranous structures to form the asymmetrical organelles. Initially the membranous organelles had a homogeneous matrix but later became filled with quantities to 6- 8-nm filaments. Following the meiotic reduction divisions each cell assumed a bipolar configuration. The membranous organelles and mitochondria were confined to the broad anterior region while the non-membrane bound nucleus became located in the narrow posterior region. Golgi membranes, endoplasmic reticulum, and numerous ribosomes were sloughed from the main cell body. The filaments lost their association with the membranous organelles and attached to the plasma membrane while the membranous portion of each organelle became progressively more complex and assumed a peripheral position in the cytoplasm. The resulting spermatid, with its condensed, posteriorly-projected nucleus, and broad anterior cytoplasm, had a tadpolelike appearance. Subsequent to deposition in the female uterus the membranous organelles fused with the plasma membrane and the mature spermatozoa became pleomorphic and moved in an ameboid manner. Because the pseudopods in the mature cell originated in those areas where the filaments previously attached to the plasma membrane it is surmised that the filaments consist of, or contain, actin. The significance of the fusion of the membranous organelles with the sperm plasma membrane, however, remains unknown.