1. THE PITUITARY GLAND
31
4. GONADOTROPS (8 AND y CELLS)
When adequately identified, the gonadotrops of teleosts have usually
been found located in the proximal pars distalis, and most often in the
ventral part of this region (Stahl, 1963). However, gonadotrops also
spread into the rostra1 pars distalis at sexual maturity in the eel (Olivereau, 1967a), salmon (van Overbeeke and McBride, 1967), and trout
(Baker, 1968). They are typical mucoid cells containing granules that
react strongly in the PAS procedure and are assumed to contain glycoproteins. For most practical purposes, this property amounts to a redefinition of the old category “basophil cells,” just as the absence of
typical PAS + ve granules defines the serous cells which are equivalent
to the old category of “acidophil cells.” With this definition in mind it is
often convenient to continue using the terms “acidophil” and “basophil,”
as long as one remembers that the terms have no reference to affinities
for acidic or basic dyes (Herlant, 1965; Purves, 1966); these older terms
are so deeply entrenched in general usage that their replacement by
“serous” and “mucoid cells, although frequently advocated, is unlikely
to materialize. In nearly all cases reported, gonadotrop granules in teleosts
stain with PAS, AF, and AB, and with Aniline blue in the common
trichrome and tetrachrome techniques.
The appearance of the gonadotrops varies greatly during the cyclic
development of the gonads, and the cells are best characterized by an
account of their annual or shorter cyclic changes. However, one very
important point to be dealt with first concerns the question of whether
teleosts possess only one type of gonadotrops or two. Higher vertebrates,
with the established possession of two gonadotropic hormones (FSH and
LH), have generally been found to have two kinds of gonadotrops in the
pituitary, the / 3 cell secreting FSH and the y cell secreting LH. Since
there is in fact no very definite physiological or biochemical evidence for
the presence of two distinct gonadotropins in teleosts (see Pickford and
Atz, 1957; Ball, 1960; Olivereau, 1967a, discussion), even in those fishes
which have been found to possess two distinct kinds of gonadotrops, one
may not apply the terms “beta” and “gamma” to these cells.
The eel (Olivereau and Herlant, 1960; Olivereau, 1967a) and the
Pacific salmon (Olivereau and Ridgeway, 1962) are two of the teleost
species in which gonadotrops can be separated into two types, with
characteristics summarized in Table I and illustrated in Fig. 16. It will be
seen that in these cases the distinction depends not only on tinctorial
features but also on position, cell size, and granule size and morphological
features such as vacuolation. The two types in the eel appear to be
equivalent in both males and females. Measurements showed that the
31
4. GONADOTROPS (8 AND y CELLS)
When adequately identified, the gonadotrops of teleosts have usually
been found located in the proximal pars distalis, and most often in the
ventral part of this region (Stahl, 1963). However, gonadotrops also
spread into the rostra1 pars distalis at sexual maturity in the eel (Olivereau, 1967a), salmon (van Overbeeke and McBride, 1967), and trout
(Baker, 1968). They are typical mucoid cells containing granules that
react strongly in the PAS procedure and are assumed to contain glycoproteins. For most practical purposes, this property amounts to a redefinition of the old category “basophil cells,” just as the absence of
typical PAS + ve granules defines the serous cells which are equivalent
to the old category of “acidophil cells.” With this definition in mind it is
often convenient to continue using the terms “acidophil” and “basophil,”
as long as one remembers that the terms have no reference to affinities
for acidic or basic dyes (Herlant, 1965; Purves, 1966); these older terms
are so deeply entrenched in general usage that their replacement by
“serous” and “mucoid cells, although frequently advocated, is unlikely
to materialize. In nearly all cases reported, gonadotrop granules in teleosts
stain with PAS, AF, and AB, and with Aniline blue in the common
trichrome and tetrachrome techniques.
The appearance of the gonadotrops varies greatly during the cyclic
development of the gonads, and the cells are best characterized by an
account of their annual or shorter cyclic changes. However, one very
important point to be dealt with first concerns the question of whether
teleosts possess only one type of gonadotrops or two. Higher vertebrates,
with the established possession of two gonadotropic hormones (FSH and
LH), have generally been found to have two kinds of gonadotrops in the
pituitary, the / 3 cell secreting FSH and the y cell secreting LH. Since
there is in fact no very definite physiological or biochemical evidence for
the presence of two distinct gonadotropins in teleosts (see Pickford and
Atz, 1957; Ball, 1960; Olivereau, 1967a, discussion), even in those fishes
which have been found to possess two distinct kinds of gonadotrops, one
may not apply the terms “beta” and “gamma” to these cells.
The eel (Olivereau and Herlant, 1960; Olivereau, 1967a) and the
Pacific salmon (Olivereau and Ridgeway, 1962) are two of the teleost
species in which gonadotrops can be separated into two types, with
characteristics summarized in Table I and illustrated in Fig. 16. It will be
seen that in these cases the distinction depends not only on tinctorial
features but also on position, cell size, and granule size and morphological
features such as vacuolation. The two types in the eel appear to be
equivalent in both males and females. Measurements showed that the