226
GLYCOGEN IN EIMERIA TENELLA
[ Vol. XXIV, Part IV,
reveal any appreciable quantity of glycogen. Probably it may be due to the fact
that sporozoites in tissue could not be encountered earlier than 37 hours after infec-
tion when they had already settled in epithelial cells and the reserve glycogen,
if they had any, was exhausted by that time in penetrating the host cell. Rest of
observations are in full parallel accord with the findings of Giovannola [1934] in his
investigation on E. falciformis and E. steidae. The present study confirms the
demonstration of glycogen in macrogametes and unsporulated oocysts of E. tenella.
In addition to these findings of Edgar, et al., [1944], the occurrence and topographic
location of glycogen has also been observed in detail in second generation schizont
and merozoites, microgametocytes and microgametes, the stages at which Edgar,
et al., failed to demonstrate this carbohydrate. It is obvious that the reserve
of the polysaccharide at each stage was directly proportional to the energy
requirements of the coccidium (see below).
It is, however, difficult to offer an explanation for the failure of Edger, et al.,
to find glycogen reserve in the second asexual generation, microgametocytes and
microgametes of E. tenella.
Source of endogenous glycogen
It has been generally accepted that endogenous polysaccharide in parasites
is derived from exogenous sources. Morita [1938] found that Entamoeba histolytica
specimens taken from a carbohydrate containing medium were very rich in glycogen.
Glycogen deposition in rumen ciliates runs parallel with the carbohydrate intake
of host [Usuelli, 1930 ; Trier, 1926, Westphal, 1934]. Armer [1934] demonstrated
high paraglycogen reserve in Nyctotherus ovalis taken from roaches kept on high
carbohydrate diet, as compared to the specimens recovered from starving insects
having poor polysaccharide reserves. Data on parasitic metozoa also support the
hypothesis of exogenous source of endogenous polysaccharide reserve [von Brand,
1952].
Deposition of glycogen by the coccidium was highest at the gametocytic stage
of its life cycle which is reached on fifth and sixth day of infection. Pratt [1940]
and Waxler [1949] have shown that at this stage the blood sugar content of heavily
infected chick is also the highest as compared with its level during the rest of the
course of infection. Muscle glycogen was shown to be mobilised through the pro-
cesses of glycogenolysis and glycogenesis taking place in liver. It appears that the
blood sugar content has been brought to a very high pitch to meet the excessive
demand of macrogametes which are storing large amounts of glycogen as a store
of readily available energy for sporulation after syngamy.
Ray and Gill [1954] demonstrated alkaline phosphatase in E. tenella. The
enzyme is widely distributed in nature and plays an important part in various
metabolic processes such as carbohydrate metabolism, bone formation and other
similar reactions. Blaschko and Jacobson [1951] stated that phosphatases 'play
a general part in phosphorylation process' which is of great importance in energy
transfer in cellular metabolism. Alkaiine phosphatase may be associated with
the process of dephosphorylation and deposition of glycogen in cells [Wislocki and
Dempsey, 1946]. In general, however, it has not been possible to connect the