Epigamy In Syllids

Syllids are an annelid family that are great model organisms for studying regenerative processes because they are able to renew damaged body structures. More impressively, these annelids are capable of regenerating an entire body half. Studies concerning regenerative processes in annelids are possible due to their well-known life cycles and successful reproductions in laboratory settings. Syllidae in particular have become model species in research because of their complex life cycles and reproductive methods. During reproduction, the body can undergo a process called epigamy where the posterior part of the species separates from the posterior part, becoming an epitoke. Alternatively, the body can undergo a process called schizogamy where

In the first amputation site, anterior regeneration started with invagination then blastemal formation and patterning which led to the development of the prostomium and later, resegmentation. Posterior regeneration was slow and incomplete as the body end remained in the invagination stage with no further regeneration. In the second amputation site, anterior regeneration materialized differently than the other two sites because it began slowly at first with only a few segments visible, but eventually additional segments were added sequentially after some time. Posterior regeneration occurred faster than in the first amputation site, however, it occurred in different rates and some remained in the invagination stage without any signs of blastema formation. In the third amputation site, anterior regeneration is similar to that of the second amputation site, but no more segments were added within a month. Posterior regeneration was similar to results from the second amputation

Female stolons are full of immature ovum, or oocytes, and the males contain packages of sperm. Stolons develop from a change of the posterior segments, not by segment addition. The anteriormost stolon changed morphologically into the stolon head, also, the nervous system and musculature experienced some remodeling. A dorsal oriented ring of neurites representing the stolon brain developed at the anterior of the stolon head in the attached stolon, but the ventral nerve cord was not interrupted between the body and stolon. Additionally, the body wall musculature is reduced between the body and stolon, however, the anterior third of the stolon head is free of musculature, yet a nervous system and musculature similar to stock segments were present in all further stolon segments.

According to the study, the effects of removing the proventricle region are significant because the stolonization is accelerated, only three segment and the pygidium are regenerated, and the majority of stolons produced are male. This suggests that there is a relationship between the proventricle and stolonization-regeneration; however, the proventricle’s control methods are still unknown. It has been proposed that the proventricle has an endocrine function that releases certain hormones to control the process, but morphology does not support this idea, it is a muscle