1. THE PITUITARY GLAND
11
In fresh glands of Poecilia and Fundulus kansae the 7 granules are
opaque so that the rostra1 part of the pituitary is often a dense white. In
the isopondylous forms in which the prolactin cells are arranged in
follicles, the material commonly found in the follicular lumen exhibits
variable staining, some with orange G and some with PAS, Aniline
blue, or light green (Sathyanesan, 1963; Olivereau, 1967a,b; van Overbeeke and McBride, 1967); with the electron microscope, at least some
of this material in the eel consists of a mass of membrane-bound vesicles,
probably derived from degenerating cells (Knowles and Vollrath,
1966b,d). The prolactin cells in such fish (e.g., eel, trout, and salmon)
are generally columnar, their apices bearing cilia projecting into the
follicular lumen ( Follenius, 1963a; Knowles and Vollrath, 1%6b,d),
and often with the 7 granules concentrated toward the outer cell base.
The cytoplasmic RNA (i.e., endoplasmic reticulum) usually lies between the nucleus and the outer base of the cell (Olivereau, 1967a,b;
van Overbeeke and McBride, 1967). Ultrastructural studies on the eel
revealed electron dense granules in these cells, about 280 mp diam in
freshwater Anguilla but about 350 mp in the marine Conger; the
endoplasmic reticulum lies basally, while the Golgi apparatus lies on
the other side of the nucleus, toward the follicular lumen (Knowles
and Vollrath, 196613). The Golgi apparatus in immature freshwater eels
consists of six to eight parallel cisternae forming a bowl- or cup-shaped
body; ultrastructural appearances suggest that the 7 granules are formed
here, the outer convex surface of the Golgi perhaps receiving newly
synthesized material from the closely adjacent rough endoplasmic reticulum, the concentrated materials then being released as membrane-bound
granules at the inner concave surface of the Golgi (Hopkins and Baker,
1968). In Anguilla elvers, and in adult Anguilla caught in the sea during
the spawning migration, the 7 granules are smaller than in the freshwater
stage, about 200 mp diam (Knowles and Vollrath, 1966b,d).
The prolactin cells of nonisospondylous teleosts are not grouped in
follicles and are not generally columnar (although the cells may be
elongated in some species such as the cichlid, Heterichthys cyanognathus). Usually they form a compact mass of rounded cells as in Poecilia,
generally evenly granulated. In cyprinodonts, the nucleus is frequently
indented or kidney-shaped, a feature particularly marked in Poecilia
(Fig. 10) and Fundulus heteroclitus (Emmart et al., 1966); in these
cyprinodonts, too, the Golgi image is easily visible in active cells as one
or more clear tubules among the granules, curved in a C or U shape, and
the endoplasmic reticulum, visualized by staining for RNA, forms a cap
or halo on the nucleus (Olivereau and Ball, 1964; Schreibman, 1964; Ball,
1967, 1969). In the related guppy (Poecilia = Lebistes reticulatus) and
11
In fresh glands of Poecilia and Fundulus kansae the 7 granules are
opaque so that the rostra1 part of the pituitary is often a dense white. In
the isopondylous forms in which the prolactin cells are arranged in
follicles, the material commonly found in the follicular lumen exhibits
variable staining, some with orange G and some with PAS, Aniline
blue, or light green (Sathyanesan, 1963; Olivereau, 1967a,b; van Overbeeke and McBride, 1967); with the electron microscope, at least some
of this material in the eel consists of a mass of membrane-bound vesicles,
probably derived from degenerating cells (Knowles and Vollrath,
1966b,d). The prolactin cells in such fish (e.g., eel, trout, and salmon)
are generally columnar, their apices bearing cilia projecting into the
follicular lumen ( Follenius, 1963a; Knowles and Vollrath, 1%6b,d),
and often with the 7 granules concentrated toward the outer cell base.
The cytoplasmic RNA (i.e., endoplasmic reticulum) usually lies between the nucleus and the outer base of the cell (Olivereau, 1967a,b;
van Overbeeke and McBride, 1967). Ultrastructural studies on the eel
revealed electron dense granules in these cells, about 280 mp diam in
freshwater Anguilla but about 350 mp in the marine Conger; the
endoplasmic reticulum lies basally, while the Golgi apparatus lies on
the other side of the nucleus, toward the follicular lumen (Knowles
and Vollrath, 196613). The Golgi apparatus in immature freshwater eels
consists of six to eight parallel cisternae forming a bowl- or cup-shaped
body; ultrastructural appearances suggest that the 7 granules are formed
here, the outer convex surface of the Golgi perhaps receiving newly
synthesized material from the closely adjacent rough endoplasmic reticulum, the concentrated materials then being released as membrane-bound
granules at the inner concave surface of the Golgi (Hopkins and Baker,
1968). In Anguilla elvers, and in adult Anguilla caught in the sea during
the spawning migration, the 7 granules are smaller than in the freshwater
stage, about 200 mp diam (Knowles and Vollrath, 1966b,d).
The prolactin cells of nonisospondylous teleosts are not grouped in
follicles and are not generally columnar (although the cells may be
elongated in some species such as the cichlid, Heterichthys cyanognathus). Usually they form a compact mass of rounded cells as in Poecilia,
generally evenly granulated. In cyprinodonts, the nucleus is frequently
indented or kidney-shaped, a feature particularly marked in Poecilia
(Fig. 10) and Fundulus heteroclitus (Emmart et al., 1966); in these
cyprinodonts, too, the Golgi image is easily visible in active cells as one
or more clear tubules among the granules, curved in a C or U shape, and
the endoplasmic reticulum, visualized by staining for RNA, forms a cap
or halo on the nucleus (Olivereau and Ball, 1964; Schreibman, 1964; Ball,
1967, 1969). In the related guppy (Poecilia = Lebistes reticulatus) and