1. THE PITUITARY GLAND
25
effects on the ACTH cells in the eel, unlike Hippocumpus (Olivereau,
196613, 1 9 6 9 ~ ) .
The ACTH cells persisted, although in reduced numbers, in ectopic
pituitary transplants in Poecilia formosa which continued to secrete small
amounts of ACTH (Ball et al., 1965; Olivereau and Ball, 1966). However, these cells in the eel pituitary in vitro present an appearance of
increased activity, showing degranulation, increased nuclear sue, and
rapid incorporation of radiouridine (Baker, 1968). In the trout the ACTH
cells in culture display a marked migration of their granules toward the
pole of the cells facing the neurohypophysis; this phenomenon is difficult
to interpret, but recent unpublished work by Baker shows that, as in the
eel, these trout cells displayed intense nuclear incorporation of radiouridine. Nevertheless, the granulation continues to accumulate at the pole
of the cell, which suggests inhibition of release, in contrast to the degranulation of the eel cells. Thus there may well be marked species variations in the response of the ACTH cells to hypothalamic disconnection.
3. GROWTH HORMONE CELLS (SOMATOTROPS, a! CELLS,
GH CELLS, OR STH CELLS)
The a! cells are the most prominent acidophils in the pars distalis, especially in marine fishes with inactive prolactin cells, and occupy much of
the proximal pars distalis. They have been described and recognized as
a distinct cell type for many years and in many species (Olivereau,
1963b). These are the cells that conform to the classic category of acidophi1 cells, staining intensely and selectively with orange G in the various
trichrome and tetrachrome techniques. For many years the existence of
two types of acidophils has been recognized in mammals and other tetrapods, one type staining selectively with orange G ( a cells) and the other
type ( q cells) with azocarmine or erythrosin (Herlant, 1!364, 1965; Purves
1966). However, the distinction is not always easy to obtain in all species
and with all dyes and techniques (Purves, 1966) ; and although the distinction can be made in teleosts, here too it is delicate and not always
easy. In the case of well-known pituitaries, such as Anguilla or Poecilia,
this difficulty is not always important, since once established that one can
in some circumstances make this tinctorial differentiation, one can always
separate the (Y and 7 cells on the basis of their location and morphology;
but with any new or little-known teleostean gland it is advisable to spend
time and effort in establishing this point before making definitive identification of the a and 7 cells. It needs to be emphasized that the pituitaries
of different fishes vary greatly in their staining reactions to any particular
25
effects on the ACTH cells in the eel, unlike Hippocumpus (Olivereau,
196613, 1 9 6 9 ~ ) .
The ACTH cells persisted, although in reduced numbers, in ectopic
pituitary transplants in Poecilia formosa which continued to secrete small
amounts of ACTH (Ball et al., 1965; Olivereau and Ball, 1966). However, these cells in the eel pituitary in vitro present an appearance of
increased activity, showing degranulation, increased nuclear sue, and
rapid incorporation of radiouridine (Baker, 1968). In the trout the ACTH
cells in culture display a marked migration of their granules toward the
pole of the cells facing the neurohypophysis; this phenomenon is difficult
to interpret, but recent unpublished work by Baker shows that, as in the
eel, these trout cells displayed intense nuclear incorporation of radiouridine. Nevertheless, the granulation continues to accumulate at the pole
of the cell, which suggests inhibition of release, in contrast to the degranulation of the eel cells. Thus there may well be marked species variations in the response of the ACTH cells to hypothalamic disconnection.
3. GROWTH HORMONE CELLS (SOMATOTROPS, a! CELLS,
GH CELLS, OR STH CELLS)
The a! cells are the most prominent acidophils in the pars distalis, especially in marine fishes with inactive prolactin cells, and occupy much of
the proximal pars distalis. They have been described and recognized as
a distinct cell type for many years and in many species (Olivereau,
1963b). These are the cells that conform to the classic category of acidophi1 cells, staining intensely and selectively with orange G in the various
trichrome and tetrachrome techniques. For many years the existence of
two types of acidophils has been recognized in mammals and other tetrapods, one type staining selectively with orange G ( a cells) and the other
type ( q cells) with azocarmine or erythrosin (Herlant, 1!364, 1965; Purves
1966). However, the distinction is not always easy to obtain in all species
and with all dyes and techniques (Purves, 1966) ; and although the distinction can be made in teleosts, here too it is delicate and not always
easy. In the case of well-known pituitaries, such as Anguilla or Poecilia,
this difficulty is not always important, since once established that one can
in some circumstances make this tinctorial differentiation, one can always
separate the (Y and 7 cells on the basis of their location and morphology;
but with any new or little-known teleostean gland it is advisable to spend
time and effort in establishing this point before making definitive identification of the a and 7 cells. It needs to be emphasized that the pituitaries
of different fishes vary greatly in their staining reactions to any particular