Follicle Cells of Styela plicata Eggs (Ascidiacea)

Effects of tributyltin(IV) chloride on fertilization of Styela plicata (Ascidiacea: Tunicata): II. Scanning and transmission electron microscopy studies

“…The absence of spermatozoa on the egg surface or on the vitelline coat could be explained by the absence of the follicle cells, which, in S. plicata, primarily play an attracting function. 18 In conclusion, the results reported above could give further early information on reproductive perturbation caused by TBTCl in ascidians resulting in altered functionality or even gametes death, leading to the species being unable to reproduce. As far as the ability of different species to contrast the effects of TBTCl, we can deduce that gametes of S. plicata seem to be more resistant than those of A. malaca.…”

“…In fact, in S. plicata, a prolonged time of incubation and/or higher concentrations of TBT are necessary to detect the anomalies that prevent the fertilization process. However, in any case, fertilization does not occur for at least three reasons: the absence of follicle cells necessary for sperm-egg interaction 8 and the strong anomalies of the vitelline coat, which is considered to be the site of the species-specific binding, 9 and the lack of mobility and alterations of the spermatozoa.…”

“…7 Fertilization in ascidians is a multistep process where egg envelopes, mainly follicle cells and the vitelline coat, are involved. 8,9 …”

Biological activity studies on organotin(IV)n+ complexes and parent compounds

“…However, in any case, fertilization does not occur for at least three reasons: the absence of follicle cells necessary for sperm-egg interaction and the strong anomalies of the vitelline coat, which is considered to be the site of the species-specific binding, and the lack of mobility and alterations of the spermatozoa [126,127].…”

“…After 5 h of treatment with 10 À5 M TBTCl, a few spermatozoa, with very anomalous heads, have been detected. The absence of spermatozoa on the egg surface or on the vitelline coat could be explained by the absence of the follicle cells, which, in S. plicata, primarily play an attracting function [124].…”