84
J, N. BALL AND BRIDGET I. BAKER
ciated with the floor of the cranium (Fig. 2%). In sharks and certain
rays, the entire pars distalis is hollow, the anterior part of the dorsal lobe
(head of dorsal lobe, cf. Mellinger, 1966) containing vesicles or tubules
communicating with the central hypophysial cavity, and the posterior
part (tail of dorsal lobe) consisting simply of folds of tissue around the
hypophysial cavity. In other skates and rays, the hypophysial cavity may
be small or obliterated, and the dorsal lobe is a compact mass of cords
and clusters of cells (Wingstrand, 1966a). The ventral lobe in all cases is
hollow, described as containing vesicles (Dodd et al., 1960; Mellinger,
1962b; Wingstrand, 1966a). In the aberrant chimaeroids, the gland
displays a hollow dorsal lobe, and a separated structure, composed of
follicles of cells, which may represent a detached ventral lobe (Sathyanesan, 1965b; Jasinski and Gorbman, 1966). All these spaces and vesicles
may contain a colloid, which is PAS + ve, A F + ve, and AB + ve (Dodd
et al., 1960, 1963; Mellinger, 196213, 1966; Sathyanesan, 1965b; Jasinski
and Gorbman, 1966). The suggestion has been made that this colloid
in the vesicles of the ventral lobe may represent a store of gonadotropins
and thyrotropin (Dodd et al., 1960, 1963), but Mellinger (196213) believes that secretion of the colloid throughout these hypophysial spaces
is a nonspecific function of the cells lining the cavities, including the
endocrine cells (T, Q, and V, see below) and certain noqendocrine cells.
One is reminded of the follicles of the rostra1 pars distalis in some
actinopterygians, which frequently contain a PAS + ve colloidal material
(Sections I1 and 111).
Experiments involving surgical hypophysectomy ( total or partial)
and replacement therapy with mammalian hormones have suggested that
the ventral lobe secretes gonadotropin(s) in dogfish and skate (Dodd
et al., 1960; Dodd, 1960). Assays of digerent regions of the gland for
TSH also locate thyrotropic function in the ventral lobe (Dent and Dodd,
1961; Dodd et al., 1963). ACTH activity has been located in the head
of the dorsal lobe by bioassay (deRoos and deRoos, 1967).
The limited information available about cell types in the gland does
not always correlate with this physiological data. In the head of the
dorsal lobe are found strongly PAS + ve cells (Dodd et al., 1960).
Mellinger (1962b, 1966) terms these the “T cells,” and showed in various
species that they are A F - ve and AB - ve and acidophilic. The T cells
he equates with the , 8 cells of Della Corte and Chieffi (1961) and Chieffi
(1962); the Italian workers thought that these cells produced TSH, but
Mellinger believes that they secrete growth hormone. The T cells occupy
the region in which deRoos and deRoos (1967) located ACTH activity.
In the tail of the dorsal lobe, Mellinger finds Q cells, PAS + ve to a
variable extent, A F - ve and AB - ve and acidophilic, which he sug-
J, N. BALL AND BRIDGET I. BAKER
ciated with the floor of the cranium (Fig. 2%). In sharks and certain
rays, the entire pars distalis is hollow, the anterior part of the dorsal lobe
(head of dorsal lobe, cf. Mellinger, 1966) containing vesicles or tubules
communicating with the central hypophysial cavity, and the posterior
part (tail of dorsal lobe) consisting simply of folds of tissue around the
hypophysial cavity. In other skates and rays, the hypophysial cavity may
be small or obliterated, and the dorsal lobe is a compact mass of cords
and clusters of cells (Wingstrand, 1966a). The ventral lobe in all cases is
hollow, described as containing vesicles (Dodd et al., 1960; Mellinger,
1962b; Wingstrand, 1966a). In the aberrant chimaeroids, the gland
displays a hollow dorsal lobe, and a separated structure, composed of
follicles of cells, which may represent a detached ventral lobe (Sathyanesan, 1965b; Jasinski and Gorbman, 1966). All these spaces and vesicles
may contain a colloid, which is PAS + ve, A F + ve, and AB + ve (Dodd
et al., 1960, 1963; Mellinger, 196213, 1966; Sathyanesan, 1965b; Jasinski
and Gorbman, 1966). The suggestion has been made that this colloid
in the vesicles of the ventral lobe may represent a store of gonadotropins
and thyrotropin (Dodd et al., 1960, 1963), but Mellinger (196213) believes that secretion of the colloid throughout these hypophysial spaces
is a nonspecific function of the cells lining the cavities, including the
endocrine cells (T, Q, and V, see below) and certain noqendocrine cells.
One is reminded of the follicles of the rostra1 pars distalis in some
actinopterygians, which frequently contain a PAS + ve colloidal material
(Sections I1 and 111).
Experiments involving surgical hypophysectomy ( total or partial)
and replacement therapy with mammalian hormones have suggested that
the ventral lobe secretes gonadotropin(s) in dogfish and skate (Dodd
et al., 1960; Dodd, 1960). Assays of digerent regions of the gland for
TSH also locate thyrotropic function in the ventral lobe (Dent and Dodd,
1961; Dodd et al., 1963). ACTH activity has been located in the head
of the dorsal lobe by bioassay (deRoos and deRoos, 1967).
The limited information available about cell types in the gland does
not always correlate with this physiological data. In the head of the
dorsal lobe are found strongly PAS + ve cells (Dodd et al., 1960).
Mellinger (1962b, 1966) terms these the “T cells,” and showed in various
species that they are A F - ve and AB - ve and acidophilic. The T cells
he equates with the , 8 cells of Della Corte and Chieffi (1961) and Chieffi
(1962); the Italian workers thought that these cells produced TSH, but
Mellinger believes that they secrete growth hormone. The T cells occupy
the region in which deRoos and deRoos (1967) located ACTH activity.
In the tail of the dorsal lobe, Mellinger finds Q cells, PAS + ve to a
variable extent, A F - ve and AB - ve and acidophilic, which he sug-