1. THE PITUITARY GLAND
51
azocarmine or orange G), or amphiphilic, taking both the blue and
orange components in trichrome and tetrachrome techniques. Some species have been described as having only one chromophilic cell type in
this region, together with chromophobes (e.g., the guppy, Follenius,
1963a, 1965a; Oncorhynchus, van Overbeeke and McBride, 1967), or all
the cells in the pars intermedia may appear chromophobic (Rutilus, Matty
and Matty, 1959; Carassius, Olivereau, 1962b). In such cases, it is impossible to be certain that two cell types exist, although probably, as in the
case of Carassius ( Olivereau, 1964a), more detailed investigations would
reveal this to be so. Within any one species the staining properties may
vary, depending on the physiological conditions of the cells and also on
the techniques applied. Thus, in Perca fluviatilis, the PAS + ve cells
bordering the neurohypophysis have been described as basophilic (Matty
and Matty, 1959) or acidophilic (Follenius and Porte, 1961b). A more
precise differentiation between two pars intermedia cell types is achieved
by staining with PAS followed by lead hematoxylin ( PbH) (see Fig. 9).
The resulting differentiation was first described in Mugilids by
Stahl (1958): One cell type, oval in shape and bordering the neurohypophysis, was PAS + ve, and a second type, lying further from the
neurohypophysis but connected to it by cellular prolongations, was
PAS - ve but PbH + ve. Several teleostean pituitaries have since been
examined by this technique, and generally the two types of cells have been
differentiated (Baker, 1963b; Olivereau, 1964a; Olivereau and Ball, 1964;
Knowles and Vollrath, 196f3a; Mattheij and van Oordt, 1967). The
PbH + ve cells frequently have a “club shape as in Mugil, and they are
often chromophobic by classic techniques ( e.g., Carassius, Olivereau,
1962b; Poecilia) .
Two cell types are not invariably present in the pars intermedia; for
example, the PAS + ve cell appears to be missing from salmonids, in
which all the cells look alike and stain with PbH (Baker, 1963a,b). However, most species studied display a PAS + ve cell type, often together
with a chromophobe that no doubt represents the PbH + ve cell (Da
Lage, 1958; Matty and Matty, 1959; Follenius, 1963a, 1965a; Schreibman,
1964; Lagios, 1965; &tan, 1966a,b). Although PAS and PbH appear to
be mutually exclusive in staining the two cell types, there seems to be no
correlation between the reactions of the cells to trichrome stains on the
one hand and to PAS on the other; thus, the PAS+ve cells may be
basophilic as in Hippocampus, Phoxinus, and Anguilla, or acidophilic as
in Cichlasoma, Blennius, and Zoarces, or amphiphilic as in Poecilia
Zutipinna. It is our impression that the reaction of these cells in mixed
staining techniques is more than usually sensitive to slight variations in
timing, strengths of dye solutions, etc. Similarly the PbH + ve cells have
51
azocarmine or orange G), or amphiphilic, taking both the blue and
orange components in trichrome and tetrachrome techniques. Some species have been described as having only one chromophilic cell type in
this region, together with chromophobes (e.g., the guppy, Follenius,
1963a, 1965a; Oncorhynchus, van Overbeeke and McBride, 1967), or all
the cells in the pars intermedia may appear chromophobic (Rutilus, Matty
and Matty, 1959; Carassius, Olivereau, 1962b). In such cases, it is impossible to be certain that two cell types exist, although probably, as in the
case of Carassius ( Olivereau, 1964a), more detailed investigations would
reveal this to be so. Within any one species the staining properties may
vary, depending on the physiological conditions of the cells and also on
the techniques applied. Thus, in Perca fluviatilis, the PAS + ve cells
bordering the neurohypophysis have been described as basophilic (Matty
and Matty, 1959) or acidophilic (Follenius and Porte, 1961b). A more
precise differentiation between two pars intermedia cell types is achieved
by staining with PAS followed by lead hematoxylin ( PbH) (see Fig. 9).
The resulting differentiation was first described in Mugilids by
Stahl (1958): One cell type, oval in shape and bordering the neurohypophysis, was PAS + ve, and a second type, lying further from the
neurohypophysis but connected to it by cellular prolongations, was
PAS - ve but PbH + ve. Several teleostean pituitaries have since been
examined by this technique, and generally the two types of cells have been
differentiated (Baker, 1963b; Olivereau, 1964a; Olivereau and Ball, 1964;
Knowles and Vollrath, 196f3a; Mattheij and van Oordt, 1967). The
PbH + ve cells frequently have a “club shape as in Mugil, and they are
often chromophobic by classic techniques ( e.g., Carassius, Olivereau,
1962b; Poecilia) .
Two cell types are not invariably present in the pars intermedia; for
example, the PAS + ve cell appears to be missing from salmonids, in
which all the cells look alike and stain with PbH (Baker, 1963a,b). However, most species studied display a PAS + ve cell type, often together
with a chromophobe that no doubt represents the PbH + ve cell (Da
Lage, 1958; Matty and Matty, 1959; Follenius, 1963a, 1965a; Schreibman,
1964; Lagios, 1965; &tan, 1966a,b). Although PAS and PbH appear to
be mutually exclusive in staining the two cell types, there seems to be no
correlation between the reactions of the cells to trichrome stains on the
one hand and to PAS on the other; thus, the PAS+ve cells may be
basophilic as in Hippocampus, Phoxinus, and Anguilla, or acidophilic as
in Cichlasoma, Blennius, and Zoarces, or amphiphilic as in Poecilia
Zutipinna. It is our impression that the reaction of these cells in mixed
staining techniques is more than usually sensitive to slight variations in
timing, strengths of dye solutions, etc. Similarly the PbH + ve cells have