Because hermatypic species use symbiotic algal photosynthesis, most of the literature in this field focuses on this autotrophic mode and very little research has studied the morphology of the coral’s digestive system or the digestion process of particulate food. Using histology and histochemestry, our research reveals that Stylophora pistillata’s digestive system is concentrated at the corals’ peristome, actinopharynx and mesenterial filaments (MF). We used in-situ hybridization (ISH) of the RNA transcript of the gene that codes for the S. pistillata digestive enzyme, chymotrypsinogen, to shed light on the functionality of the digestive system. Both the histochemistry and the ISH pointed to the MF being specialized digestive organs, equipped with large numbers of acidophilic and basophilic granular gland cells, as well as acidophilic non-granular gland cells, some of which produce chymotrypsinogen. We identified two types of MF: short, trilobed MF and unilobed, long and convoluted MF. Each S. pistillata polyp harbors two long convoluted MF and 10 short MF. While the short MF have neither secreting nor stinging cells, each of the convoluted MF display gradual cytological changes along their longitudinal axis, alternating between stinging and secreting cells and three distinctive types of secretory cells. These observations indicate the important digestive role of the long convoluted MF. They also indicate the existence of novel feeding compartments in the gastric cavity of the polyp, primarily in the nutritionally active peristome, in the actinopharynx and in three regions of the MF that differ from each other in their cellular components, general morphology and chymotrypsinogen excretion.
Bibliographical noteFunding Information:
We are grateful to the Hillel Yaffe Hospital Medical School for letting us use their digital photography equipment and to Z. Lapidot, M. Oren and T. Rozentsvig for their assistance during the different stages of the research. We thank G. Paz for his help with the graphic work in this paper. This research was supported by the EC INCO-DEV project (REEFRES-510657) and by the AID-MERC program (no. M33-001).
© 2017, Springer-Verlag Berlin Heidelberg.
- Mesenterial filaments
- Stylophora pistillata
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Cell Biology