40
J. N. BALL AND BRIDGET I. BAKER
characterized by partial or total loss of the coarse glycoprotein granulation and development of vacuoles, in the presence of cytological evidence
of marked synthetic and excretory activity (large nucleus and nucleolus,
prominent Golgi image, and abundant cytoplasmic RNA). In addition to
glycoprotein secretory granules, the active cells contain small numbers of
larger amphiphilic granules or droplets, which have a varied staining
affinity (positive to PAS, orange G, and erythrosin). They are negative to
Alcian blue, however, so that in Ox-AB-PAS preparations these large
magenta granules (R granules) contrast with the smaller dark blue
secretory granules ( B granules), The R granules are absent or very rare
in quiescent cells, but they become numerous in the active state and are
often to be seen lining the vacuoles that are characteristic of late
vitellogenesis.
Orange G positive granules, no doubt equivalent to the R granules of
Poecilia, have been described in gonadotrops of Xiphophow, being
particularly numerous together with vacuoles in the gonadotrops of
gravid fish, presumably corresponding to the early pregnancy condition
of Poecilia ( Schreibman, 1964; see Table I11 ) . The putative gonadotrops
of Oncorhynchus contain large and small granules, the former being
PAS + ve but AB - ve, while the small granules are positive to both
PAS and AB (van Overbeeke and McBride, 1967) ; also in Oncorhynchus,
the type 1 gonadotrops of Olivereau (Table I ) lose their glycoprotein
granulation after spawning and develop vacuoles containing large OG +
ve granules (illustrated in Olivereau, 1963b), a feature very like the
appearance of R granules in Poecilia gonadotrops in late vitellogenesis
( Tables I1 and 111). A similar phenomenon is seen in the gonadotrops of
S a l m salar (Olivereau, 1954). The gonadotrops of Tor (Barbus) tor
contain, in addition to glycoprotein granules, carminophilic granules that
are particularly abundant in the vacuolated gonadotrops at the peak of
their secretory activity ( Rai, 1966a,b). The development of vacuoles
[which Olivereau and Fontaine (1966) consider may indicate impending
cellular exhaustion] together with these acidophilic or amphiphilic granules and partial or total loss of glycoprotein granulation seems typical of
the teleostean gonadotrop when highly active. As Olivereau (1967a) has
suggested, the amphiphilic granules may be lysosomes; similar bodies
occur in gonadotrops of amphibians ( Zuber-Vogeli, 1953; van Oordt,
1963), and lysosomes, with staining properties similar to those of these
bodies in fish and amphibian gonadotrops, are known to be present in the
basophils of the human pituitary ( Herlant, 1965). Presumably lysosomes
would serve to rid the cell of excess secretory products, which may explain the marked development of R granules during early pregnancy in
Poecilia, when oocyte growth ( = gonadotropin secretion) is arrested,
J. N. BALL AND BRIDGET I. BAKER
characterized by partial or total loss of the coarse glycoprotein granulation and development of vacuoles, in the presence of cytological evidence
of marked synthetic and excretory activity (large nucleus and nucleolus,
prominent Golgi image, and abundant cytoplasmic RNA). In addition to
glycoprotein secretory granules, the active cells contain small numbers of
larger amphiphilic granules or droplets, which have a varied staining
affinity (positive to PAS, orange G, and erythrosin). They are negative to
Alcian blue, however, so that in Ox-AB-PAS preparations these large
magenta granules (R granules) contrast with the smaller dark blue
secretory granules ( B granules), The R granules are absent or very rare
in quiescent cells, but they become numerous in the active state and are
often to be seen lining the vacuoles that are characteristic of late
vitellogenesis.
Orange G positive granules, no doubt equivalent to the R granules of
Poecilia, have been described in gonadotrops of Xiphophow, being
particularly numerous together with vacuoles in the gonadotrops of
gravid fish, presumably corresponding to the early pregnancy condition
of Poecilia ( Schreibman, 1964; see Table I11 ) . The putative gonadotrops
of Oncorhynchus contain large and small granules, the former being
PAS + ve but AB - ve, while the small granules are positive to both
PAS and AB (van Overbeeke and McBride, 1967) ; also in Oncorhynchus,
the type 1 gonadotrops of Olivereau (Table I ) lose their glycoprotein
granulation after spawning and develop vacuoles containing large OG +
ve granules (illustrated in Olivereau, 1963b), a feature very like the
appearance of R granules in Poecilia gonadotrops in late vitellogenesis
( Tables I1 and 111). A similar phenomenon is seen in the gonadotrops of
S a l m salar (Olivereau, 1954). The gonadotrops of Tor (Barbus) tor
contain, in addition to glycoprotein granules, carminophilic granules that
are particularly abundant in the vacuolated gonadotrops at the peak of
their secretory activity ( Rai, 1966a,b). The development of vacuoles
[which Olivereau and Fontaine (1966) consider may indicate impending
cellular exhaustion] together with these acidophilic or amphiphilic granules and partial or total loss of glycoprotein granulation seems typical of
the teleostean gonadotrop when highly active. As Olivereau (1967a) has
suggested, the amphiphilic granules may be lysosomes; similar bodies
occur in gonadotrops of amphibians ( Zuber-Vogeli, 1953; van Oordt,
1963), and lysosomes, with staining properties similar to those of these
bodies in fish and amphibian gonadotrops, are known to be present in the
basophils of the human pituitary ( Herlant, 1965). Presumably lysosomes
would serve to rid the cell of excess secretory products, which may explain the marked development of R granules during early pregnancy in
Poecilia, when oocyte growth ( = gonadotropin secretion) is arrested,