234
RUTH BELLAIRS
and a mass of mitochondria (van Durme, 1914; Brambell, 1926; Das,
1931; Sluiter, 1940; Guraya, 1962). In addition, various authors have
described lipid bodies as lying in this part of the oocyte (Konopacka.
1933; Marza and Marza, 1935; Guraya, 1957, 1962) and the region is
said to be rich in RNA (Guraya, 1962).
Different authors have applied the term Balbiani body (or a similar
term) to one or more of these components. It is possible that all are
present, but it is difficult to be certain from light microscopy, and the
region has not yet been studied by electron microscopy. A factor which
adds to the difficulties of interpretation is that several authors have
used relatively non-specific staining techniques. For instance, fat
stains have been used not only to identify lipid drops (Konopacka,
1933) but also the Golgi apparatus (Brambell (1926) and Nama (1956)
used osmium tetroxide) and mitochondria (Brambell (1926) used
osmium tetroxide).
Brambell (1926) suggested that because of the confusion the term
Balbiani body should be dropped, and that instead the specific components should be identified individually. A further objection to the
term is that it implies that yolk is definitely formed from that region of the
oocyte, a supposition that has now been discarded by most investigators.
2. The Nature of the Dispersed 'Balbiani Body'
The dispersal of this region has taken place by the time the oocyte is
about 0-3 mm in diameter. The structures which disperse in this way
and come to lie peripherally are the mitochondria (van Durme, 1914;
Brambell, 1926; Marza and Marza, 1935; Sluiter, 1940; Varma, 1954)
and the Golgi apparatus (Brambell, 1926; Marza and Marza, 1935;
Sluiter, 1940), though owing to the use of fat stains some authors have
identified them as lipid drops (Konopacka, 1933). With the advantages of
electron microscopy, however, it is possible to demonstrate clearly that
the subcortical layer of 'granules' seen by light microscopy consists of a
series of Golgi apparati in close association with mitochondria (Fig. 11).
Fat drops lie proximal to them.
3. The 'Vacuoles'
Yolk spheres are formed from 'vacuoles' which are easily visible with
both light and electron microscopy by the time the oocyte is about 2
mm diameter. They lie proximal to the subcortical layer of mitochondria
but soon spread throughout most of the cytoplasm of the oocyte
(Debuisson, 1906 ; Brambell, 1926 ; Konopacka, 1933 : Marza and Marza,
1935; Sluiter, 1940). At first they appear transparent by light microscopy, and stain poorly. According to Marza and Marza (1935) they
stain with neutral red, but not with such fat stains as Sudan III or Nile
RUTH BELLAIRS
and a mass of mitochondria (van Durme, 1914; Brambell, 1926; Das,
1931; Sluiter, 1940; Guraya, 1962). In addition, various authors have
described lipid bodies as lying in this part of the oocyte (Konopacka.
1933; Marza and Marza, 1935; Guraya, 1957, 1962) and the region is
said to be rich in RNA (Guraya, 1962).
Different authors have applied the term Balbiani body (or a similar
term) to one or more of these components. It is possible that all are
present, but it is difficult to be certain from light microscopy, and the
region has not yet been studied by electron microscopy. A factor which
adds to the difficulties of interpretation is that several authors have
used relatively non-specific staining techniques. For instance, fat
stains have been used not only to identify lipid drops (Konopacka,
1933) but also the Golgi apparatus (Brambell (1926) and Nama (1956)
used osmium tetroxide) and mitochondria (Brambell (1926) used
osmium tetroxide).
Brambell (1926) suggested that because of the confusion the term
Balbiani body should be dropped, and that instead the specific components should be identified individually. A further objection to the
term is that it implies that yolk is definitely formed from that region of the
oocyte, a supposition that has now been discarded by most investigators.
2. The Nature of the Dispersed 'Balbiani Body'
The dispersal of this region has taken place by the time the oocyte is
about 0-3 mm in diameter. The structures which disperse in this way
and come to lie peripherally are the mitochondria (van Durme, 1914;
Brambell, 1926; Marza and Marza, 1935; Sluiter, 1940; Varma, 1954)
and the Golgi apparatus (Brambell, 1926; Marza and Marza, 1935;
Sluiter, 1940), though owing to the use of fat stains some authors have
identified them as lipid drops (Konopacka, 1933). With the advantages of
electron microscopy, however, it is possible to demonstrate clearly that
the subcortical layer of 'granules' seen by light microscopy consists of a
series of Golgi apparati in close association with mitochondria (Fig. 11).
Fat drops lie proximal to them.
3. The 'Vacuoles'
Yolk spheres are formed from 'vacuoles' which are easily visible with
both light and electron microscopy by the time the oocyte is about 2
mm diameter. They lie proximal to the subcortical layer of mitochondria
but soon spread throughout most of the cytoplasm of the oocyte
(Debuisson, 1906 ; Brambell, 1926 ; Konopacka, 1933 : Marza and Marza,
1935; Sluiter, 1940). At first they appear transparent by light microscopy, and stain poorly. According to Marza and Marza (1935) they
stain with neutral red, but not with such fat stains as Sudan III or Nile