108
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
cells, especially their membrane, are more resistant to lysis than the
absorptive cells. Although the cytoplasm of the secretion cells contract
and collect around their respective nuclei, the membranes remain
intact except for some breakdown at the luminal borders. She is of
the opinion that this difference is due to the fact that the secretion
cells are not influenced by acid wastes from within since they are not
involved in the process of elimination.
In addition to the hepatopancreas, F. G. Rees has also reported
that the gonads become parasitized in instances of heavy infections.
This phenomenon has been verified by Cheng and Cooperman (1964)
who have pointed out that the reproductive system of heavily infected
gastropods generally serves as a site for secondary invasion when the
hepatopancreas becomes completely destroyed. Rees has also reported
that the rediae increase both in size and number in the intertrabeculate
spaces in the ovary and thus cause the germinal epithelium to atrophy
and ultimately become destroyed. She believes that the cell destruction
is due to a combination of deprivation of nutrients and mechanical
pressure. Subsequently, secondary transverse partitions of the germinal
epithelium become reduced to a layer of flattened cells which cover the
connective tissue of the trabeculae. In the case of extremely heavy
infections, even the trabeculae break down and are devoured by the
emerging cercariae.
It is of interest to point out at this time that F. G. Rees is of the
opinion that both physiological and mechanical factors contribute to
the breakdown of the ovarian germinal epithelium. Cheng and Cooperman (1964)) who have studied the invasion of the female reproductive
system of Helisoma trivolvis by the sporocysts and cercariae of
Glypthelmins pennsylvaniensis, interpreted the atrophy of germinal
epithelium to be due primarily, if not exclusively, to mechanical
pressure exerted by the parasites.
F. G. Rees has also reported that the male reproductive system of
Patella vulgata is invaded by the rediae and cercariae of Cercaria
patellae. Again, Rees believes that the destruction and atrophy of the
germinal epithelium and developing germinal cells are due to physiological degradation, specifically due to starvation, since the parasites
presumably ( ( consumed the food-material intended for the developing
male cells.” Her finding that C. patellae will invade the male reproductive system is of interest, as is the similar finding by W. J. Rees
(1936a) summarized at a later point, since Cheng and Cooperman (1964)
have reported that in Helisoma trivolvis parasitized by Glypthelmins
pennsylvaniensis, the parasites do not invade the male reproductive
system except accidentally through the male genital pore and become
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
cells, especially their membrane, are more resistant to lysis than the
absorptive cells. Although the cytoplasm of the secretion cells contract
and collect around their respective nuclei, the membranes remain
intact except for some breakdown at the luminal borders. She is of
the opinion that this difference is due to the fact that the secretion
cells are not influenced by acid wastes from within since they are not
involved in the process of elimination.
In addition to the hepatopancreas, F. G. Rees has also reported
that the gonads become parasitized in instances of heavy infections.
This phenomenon has been verified by Cheng and Cooperman (1964)
who have pointed out that the reproductive system of heavily infected
gastropods generally serves as a site for secondary invasion when the
hepatopancreas becomes completely destroyed. Rees has also reported
that the rediae increase both in size and number in the intertrabeculate
spaces in the ovary and thus cause the germinal epithelium to atrophy
and ultimately become destroyed. She believes that the cell destruction
is due to a combination of deprivation of nutrients and mechanical
pressure. Subsequently, secondary transverse partitions of the germinal
epithelium become reduced to a layer of flattened cells which cover the
connective tissue of the trabeculae. In the case of extremely heavy
infections, even the trabeculae break down and are devoured by the
emerging cercariae.
It is of interest to point out at this time that F. G. Rees is of the
opinion that both physiological and mechanical factors contribute to
the breakdown of the ovarian germinal epithelium. Cheng and Cooperman (1964)) who have studied the invasion of the female reproductive
system of Helisoma trivolvis by the sporocysts and cercariae of
Glypthelmins pennsylvaniensis, interpreted the atrophy of germinal
epithelium to be due primarily, if not exclusively, to mechanical
pressure exerted by the parasites.
F. G. Rees has also reported that the male reproductive system of
Patella vulgata is invaded by the rediae and cercariae of Cercaria
patellae. Again, Rees believes that the destruction and atrophy of the
germinal epithelium and developing germinal cells are due to physiological degradation, specifically due to starvation, since the parasites
presumably ( ( consumed the food-material intended for the developing
male cells.” Her finding that C. patellae will invade the male reproductive system is of interest, as is the similar finding by W. J. Rees
(1936a) summarized at a later point, since Cheng and Cooperman (1964)
have reported that in Helisoma trivolvis parasitized by Glypthelmins
pennsylvaniensis, the parasites do not invade the male reproductive
system except accidentally through the male genital pore and become