"Compartments and polyclones in insect development"

Date:
1973-1975
Reference:
PP/CRI/H/5/11
Catalogue details

Licence: In copyright

Credit: "Compartments and polyclones in insect development". Source: Wellcome Collection.

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    the frequency of mitotic recombination for larva is itself increased. This is especially trsttal in the early stages of development when the normal rate is incon veniently low. A second somewhat unexpected result was that in spite of the (M+ZMT*) clones being much larger than normal, the overall size and shape of the wing was not appreciably altered. This implies that there is a special mechanism to regulate size and shape which can cope with differential cell division rates - an important result in its own right. Having now given an indication of the methods used we must now describe the results. As already implied a marked clone is usually a single patch of cells (rather than several patches) though, especially on the wing, it may be elongated and have a somewhat irregular outline. As might have been expected the earliest clones are contained within the fairly large area of the adult cuticle produced by the entire wing disc. This shows that separation of the wing disc from the other discs producing the adult epithelium must have occurred before cells in the discs started to divide. How ever even at these early times a compartment boundary is apparent within the disc. This boundary, which separates anterior region from posterior regions, runs along the middle of the wing between the third and fourth vein. The actual demarcation line is near the fourth vein but distinct from it (see Fig. ). The demarcation . line, which runs along both surfaces of the wing, is continued on the body where it divides the notum into two distinct areas as shown in Fig. Even a very large clone oV>í< 'i-'t. (see Fig. ) will efe-scure this demarcation line though it may well at this stage «wtr tu , cross the wing margins^and appear on both dorsal and ventral surfaces. Notice that the edges of the clone are somewhat irregular except where they run along the demarcation line. It is unlikely that this lineáis the line Where two entirely separate groups of cells have come together since all the evidence suggests that both anterior and posterior regions are within the same imaginai disc and thus probably fairly close together. Since about twice as many clones appear in the anterior compartment