English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The sperm ultrastructure and spermatogenesis of the ectoparasitic polychaete Asetocalamyzas laonicola Tzetlin, 1985 (Calamyzidae) is investigated. The male cells are located freely in the coelom. The spermatocytes are large cells of irregular shape; their nuclei have condensed chromatin in the periphery. Spermatocyte cytoplasm is granular and electron-dense with several spherical mitochondria. During early developmental stages spermatids are aggregated into a rosette (four cells). The early spermatids have a tiny acrosomal vesicle at one side of the cell, a few round mitochondria at another, and electron dense nuclei. The late spermatids have elongated mitochondria, a well-developed acrosome and a flagellum. The mature sperm are threadlike with a round acrosomal vesicle, an electron-dense structure. The elongated nuclei have anterior and posterior depressions. The supporting root zone of the acrosome is located behind the acrosomal vesicle in the anterior invagination of the nuclei. Six elongated mitochondria surround the flagellum and form the midpiece of the sperm. A single centriole lies in the posterior depression of the nucleus. The middle part of the flagellum possesses a normal (9+2x2) pattern. Probably, the terminal part of flagellum is modified. The sperm structure suggests internal fertilization or another type of specialized sperm transfer in A. laonicola

scientia marina

Spermiogenesis and sperm ultrastructure of &lt;em&gt;Asetocalamyzas laonicola&lt;/em&gt; Tzetlin, 1985 (Polychaeta), an ectoparasite of the large spionid &lt;em&gt;Scolelepis&lt;/em&gt; cf. &lt;em&gt;matsugae&lt;/em&gt; Sikorsfi, 1994, from the White Sea