International Journal of Marine Science, 2016, Vol.6, No.18, 1-14
5
Figure 1-8: 1. Photomacrograph of a whole mount of
Styela plicata
. Note: wrinkled and tough tunic. 2. Photomacrograph of a whole
mount of
Ciona intestinalis
. Note: two squirts are beside each others; smooth and transparent tunic. 3. Photomicrograph of a
transverse section in intestinal mucosa of
Ciona intestinalis
showing a uninucleated zoite in an epithelial cell and a microgamont
inside a blood cell. 4. Photomicrograph of a transverse section in intestinal mucosa of
Styela plicata
showing a macrogamont and a
microgamont . Note: each gamont is present in a parasitophorous vacuole cytoplasm is filled with dense granules. Destruction of the
host cell can be noticed. 5. Photomicrograph of a transverse section in intestinal mucosa of
Styela plicata
showing two macrogamonts.
Note: large nucleus with a nucleolus. 6. Photomicrograph of a transverse section in intestinal mucosa of
Styela plicata
showing one
microgamont and other macrogamont. Note: Damage of the host cell nucleus. 7. Photomicrograph of a transverse section in intestinal
mucosa of
Ciona intestinalis
showing two microgamonts. Note: enlarged nucleus of one gamont and damage of the host cell nucleus.
8. Photomicrograph of a transverse section in intestinal mucosa of
Ciona intestinalis
showing a multinucleated microgamont inside
the paracytophorous vacuole. Note: four nuclei inside the gamont
.
Schizogony
First generation schizont
After ingesting the unsporulated sporocyst through the oral opening in both ascidians studied, a process of
sporogony occurred in the lumen of the intestine and the sporozoites released and penetrated the intestinal mucosa
where the agametic cycle started. The first generation schizont appeared afterwards and schizonts increased in
number especially in the lower part of the intestine. Different morphological appearances of the first generation
schizont were observed. Each schizont underwent stages of development and another differentiation stage to form
sporozoites. Schizonts (17.2 X 15 µm) pushed or overlooked the nucleus of the host intestinal mucosa meanwhile,
the cytoplasm of the host cell became very narrow (Fig.22). A number of projections appeared on the outer
boundary of the infected host cell and extended in the direction of the other epithelial cells at the vicinity. As their
nuclei became branched and lobulated, schizonts underwent a differentatiation process. The lobules of the
