The ultrastructure of the spermatozoon of Lernaeocera branchialis (Copepoda : Pennellidae)

Abstract

Spermatozoa are produced by males of the fish-parasitic copepod, Lernaeocera branchialis, on the flounder (Platichthysflesus) host and packaged into spermatophores. Mature spermatozoa from spermatophores have been investigated with light microscopy and t.e.m. and s.e.m. techniques. Each is a filiform cell up to 30 pm long and 1 m in diameter, being symmetrically tapered at each end to produce a 'javelin-shaped' configuration. Surface s.e.m. appearances suggest that the cell is helically twisted. The spermatozoon possesses no flagellum, no nuclear envelope, no mitochondria and no orthodox acrosome. For most of its length the cell has a four-lobed appearance in transverse section and contains little more than a cylindrical sleeve of pseudomembranous material with which is associated finely filamentous or granular material which is assumed to be nuclear chromatin. The spermatozoon is immobile in seawater.The ultrastructure of L. branchialis spermatozoa has been compared with that of eight other copepod species.

Experimental studies on the development of Lernaeocera branchialis (Copepoda: Pennellidae): population processes from egg production to maturation on the flatfish host

“…Several aspects of egg-production and development have been quantified in this study. Our finding that L. branchialis produces a series of egg strings poses intriguing questions about the methods whereby sufficient spermatozoa can be stored for long enough to fertilize them (Grant & Whitfield, 1988). Schram (1979) reported that The numbers of eggs present in a single pair of extruded egg-strings of L. branchialis are near the top of the range for fish parasitic copepods.…”

Susceptibility of the Non-Targeted Crustacean Eurytemora affinis to the Endocrine Disruptor Tebufenozide: A Transcriptomic Approach

“…The zonadhesin protein is a sperm-specific protein localized in the acrosome in mammals and it plays a role in sperm-egg interaction during fertilization [98]. The role of this gene in crustaceans and copepods remains to be elucidated, as no acrosome-like structure has been described in the sperm ultrastructure of copepods [99]. However, it is possible that the genes involved in fertility in mammals could have a similar role in copepods.…”