2 Basic Information and Overview
23
3.2 Explant Culture
Explant cultures are initiated with chopped small tissue fragments (explants). In explant cultures, cell migration from the explants will occur
first. Cells constituting explants come out and form a cell monolayer or
network around the explants. In addition, free cells may be seen near the
explants. During the next step, cells begin to divide.
3.3 Cell Growth
In both free cell and explant cultures, cell numbers increase by mitosis. If
the culture is maintained over a longer period of time by changing the
medium once a week or so, cell multiplication may continue and the cells
will cover the entire bottom area of the culture vessels. However, to attain this state, many months will usually be required.
3.4 Culture Conditions
The culture is usually maintained at 15°-30°C. In general, 37°C, which is
used for mammalian cell culture, is too high for invertebrate cells. Because all invertebrates are poikilothermic, there is no reason to maintain
cultures at 37°C. It is preferable to maintain the culture at the temperature at which the animals grow well. For insects, culture at 25°C is common. Within the acceptable temperature range, the growth rate of the
cells increases with increases in temperature. In mammalian cell culture,
a CO 2 incubator is often necessary to keep the pH of culture medium
constant during culture. However, there are no published reports of the
necessity of a CO2 incubator for culturing invertebrate cells. Most cells in
insect cell cultures are known to be insensitive to changes in pH over a
considerably wide range (Mitsuhashi, 1989).
3.S Maintenance
For a primary culture, the media should be renewed during culture. The
frequency at which the media should be changed depends on the state of
the cultured cells. If the cells multiply or the explants show active contracting movement, it is better to change the media at shorter intervals,
whereas if cultured explants and cells do not show any change, frequent
changes of the media are not recommended. It is better to replace half
the medium with fresh medium, especially during the early stages of
primary culture.
References
Becker, J. and Landureau, J.e. (1981) Specific vitamin requirements of insect cell lines (P. americana)
according to their tissue origin and in vitro conditions. In Vitro 17,471-479.
Grace, T.D.e. (1958) Effects of various substances on growth of silkworm tissues in vitro. Aust. J.
BioI. Sci. 11,407-417.
23
3.2 Explant Culture
Explant cultures are initiated with chopped small tissue fragments (explants). In explant cultures, cell migration from the explants will occur
first. Cells constituting explants come out and form a cell monolayer or
network around the explants. In addition, free cells may be seen near the
explants. During the next step, cells begin to divide.
3.3 Cell Growth
In both free cell and explant cultures, cell numbers increase by mitosis. If
the culture is maintained over a longer period of time by changing the
medium once a week or so, cell multiplication may continue and the cells
will cover the entire bottom area of the culture vessels. However, to attain this state, many months will usually be required.
3.4 Culture Conditions
The culture is usually maintained at 15°-30°C. In general, 37°C, which is
used for mammalian cell culture, is too high for invertebrate cells. Because all invertebrates are poikilothermic, there is no reason to maintain
cultures at 37°C. It is preferable to maintain the culture at the temperature at which the animals grow well. For insects, culture at 25°C is common. Within the acceptable temperature range, the growth rate of the
cells increases with increases in temperature. In mammalian cell culture,
a CO 2 incubator is often necessary to keep the pH of culture medium
constant during culture. However, there are no published reports of the
necessity of a CO2 incubator for culturing invertebrate cells. Most cells in
insect cell cultures are known to be insensitive to changes in pH over a
considerably wide range (Mitsuhashi, 1989).
3.S Maintenance
For a primary culture, the media should be renewed during culture. The
frequency at which the media should be changed depends on the state of
the cultured cells. If the cells multiply or the explants show active contracting movement, it is better to change the media at shorter intervals,
whereas if cultured explants and cells do not show any change, frequent
changes of the media are not recommended. It is better to replace half
the medium with fresh medium, especially during the early stages of
primary culture.
References
Becker, J. and Landureau, J.e. (1981) Specific vitamin requirements of insect cell lines (P. americana)
according to their tissue origin and in vitro conditions. In Vitro 17,471-479.
Grace, T.D.e. (1958) Effects of various substances on growth of silkworm tissues in vitro. Aust. J.
BioI. Sci. 11,407-417.