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ZOOLOGY: HEGNER AND RUSSELL 
the terminal chamber. After differentiation has occurred, the oocytes 
and their accompanying nurse cells lie at the anterior end of the zone 
of growth. Each oocyte is nourished by seven nurse cells which lie in 
a nurse chamber anterior to it. The arrangement of these nurse cells 
is shown in figure 2, n. 
1. Outline of an ovariole. // = terminal filament, tc — terminal chamber containing 
undifferentiated oogonia; gz = zone of growth. (X 140) 
2. A portion of growth zone, drawn from in to to preparation, showing eight cell stages, 
w = 7 nurse cells arranged in nurse chamber; o = oocyte connected with nurse chamber. 
(X 225) 
3. A single ultimate oogonium from anterior end of terminal chamber. (X 2000) 
4. Two-cell stage. Metaphase of second division, nc = nurse ceU; ogmc = oocyte 
grandmother cell containing oocyte determinant od; is = intercellular strand. (X 2000) 
5. Four-cell stage. Metaphase of third division, nc = nurse cells, omc = oocyte 
mother cell, containing oocyte determinant od; is = intercellular strand. (X 2000) 
The large terminal chamber contains at its distal end many oogonia 
ready to undergo differentiation. These ultimate oogonia (fig. 3) are 
characterized by a nucleus containing a deeply staining central mass of 
chromatin from which many fine strands radiate to the nuclear membrane. 
A few small darkly staining bodies are sometimes present in the cyto- 
plasm. The two daughter cells of such an ultimate oogonium are shown 
