1. THE PITUITARY GLAND
27
Poecilia the a cell border to the proximal pars distalis is thinner and discontinuous, the cells are poorly granulated and generally not visible in
the fresh gland.
In the sexually mature female eel, as in Poecilia, the Q cells display
a sexual dimorphism. In immature individuals of both sexes, these cells
form the greater part of the cords of the proximal pars distalis, since the
TSH cells are located in the rostra1 region, and the gonadotrops are small
and undifferentiated. At sexual maturity the cords become composed of
a mixture of (Y cells with now more numerous and larger gonadotrops.
In the mature male, the Q cells are small, with indistinct boundaries,
rather sparse granulation, and indistinct nucleolus and little or no visible
cytoplasmic RNA, whereas in the female the (Y cells are much more
numerous and often appear more active, with strongly marked cell
boundaries, large nuclei and prominent nucleoli, denser granulation,
prominent Golgi image and demonstrable cytoplasmic RNA ( Olivereau,
1967a,b; Olivereau and Olivereau, 1968). Thus in both Poecilia and
Anguilla, the (Y cells are generally more numerous and more active in
the mature female. In contrast, Schreibman (1964) found no indications
of such a sexual dimorphism in X i p h o p b w .
In both Poecilia and Anguilla (Olivereau, 1963a) the a granules are
more refractile than the 7 granules. In contrast to Poecilia, the eel a
granules are rather larger than those of the 7 cells (Olivereau, 1963a),
an observation confirmed by the electron microscope (Knowles and Vollrath, 1966b). Similar differences are found in comparisons of the two cell
types in other teleosts, some fish resembling Poecilia in having smaller
(Y granules (guppy, Follenius, 1963a; Mugil, Leray, 1966; Zoarces, bztan,
1966a; trout, Ball, 1967), while others resemble the eel in having smaller
7 granules (Perca, Follenius, 1963a; cichlids, Ball, 1967). This variability
again emphasizes that granule size alone is not a criterion of cell type
( cf. Herlant, 1965; Follenius, 1963a).
Like the 7 cells, the (Y cells are typical serous cells; that is, their
granules do not contain glycoprotein and are typically negative to PAS,
AF, and AB. A faint staining with PAS can nevertheless be obtained,
especially with the Ox-AB-PAS-OG procedure, in Poecilia and Fundulus
(Ball, 1967), the eel (Olivereau, 1967c) and other species (Follenius,
1963a; Matty and Matty, 1959). This recalls the faint staining of acidophil
granules with PAS in mammals ( Herlant, 1960; Purves, 1966), which may
reflect the lipid content of these granules (cf. Gabe, 1963; Halmi, 1963,
discussion). This PAS reaction in the teleostean a cell is too weak to cause
confusion with the strong reaction in the mucoid cells. The Q cells in
Anguilla contain SSlSH groups and are rich in protein (Olivereau,
1963a), and in Mugil they incorporate radiocysteine rapidly (Leray,
27
Poecilia the a cell border to the proximal pars distalis is thinner and discontinuous, the cells are poorly granulated and generally not visible in
the fresh gland.
In the sexually mature female eel, as in Poecilia, the Q cells display
a sexual dimorphism. In immature individuals of both sexes, these cells
form the greater part of the cords of the proximal pars distalis, since the
TSH cells are located in the rostra1 region, and the gonadotrops are small
and undifferentiated. At sexual maturity the cords become composed of
a mixture of (Y cells with now more numerous and larger gonadotrops.
In the mature male, the Q cells are small, with indistinct boundaries,
rather sparse granulation, and indistinct nucleolus and little or no visible
cytoplasmic RNA, whereas in the female the (Y cells are much more
numerous and often appear more active, with strongly marked cell
boundaries, large nuclei and prominent nucleoli, denser granulation,
prominent Golgi image and demonstrable cytoplasmic RNA ( Olivereau,
1967a,b; Olivereau and Olivereau, 1968). Thus in both Poecilia and
Anguilla, the (Y cells are generally more numerous and more active in
the mature female. In contrast, Schreibman (1964) found no indications
of such a sexual dimorphism in X i p h o p b w .
In both Poecilia and Anguilla (Olivereau, 1963a) the a granules are
more refractile than the 7 granules. In contrast to Poecilia, the eel a
granules are rather larger than those of the 7 cells (Olivereau, 1963a),
an observation confirmed by the electron microscope (Knowles and Vollrath, 1966b). Similar differences are found in comparisons of the two cell
types in other teleosts, some fish resembling Poecilia in having smaller
(Y granules (guppy, Follenius, 1963a; Mugil, Leray, 1966; Zoarces, bztan,
1966a; trout, Ball, 1967), while others resemble the eel in having smaller
7 granules (Perca, Follenius, 1963a; cichlids, Ball, 1967). This variability
again emphasizes that granule size alone is not a criterion of cell type
( cf. Herlant, 1965; Follenius, 1963a).
Like the 7 cells, the (Y cells are typical serous cells; that is, their
granules do not contain glycoprotein and are typically negative to PAS,
AF, and AB. A faint staining with PAS can nevertheless be obtained,
especially with the Ox-AB-PAS-OG procedure, in Poecilia and Fundulus
(Ball, 1967), the eel (Olivereau, 1967c) and other species (Follenius,
1963a; Matty and Matty, 1959). This recalls the faint staining of acidophil
granules with PAS in mammals ( Herlant, 1960; Purves, 1966), which may
reflect the lipid content of these granules (cf. Gabe, 1963; Halmi, 1963,
discussion). This PAS reaction in the teleostean a cell is too weak to cause
confusion with the strong reaction in the mucoid cells. The Q cells in
Anguilla contain SSlSH groups and are rich in protein (Olivereau,
1963a), and in Mugil they incorporate radiocysteine rapidly (Leray,