90
J. N. BALL AND BRIDGET I. BAKER
posteriorly, so that the two components here are in contact (Adam, 1960;
Matty, 1960), but this has not been observed by other workers (Olsson,
1959; Gorbman et al., 1963). In the anterior region of the adenohypophysis, most of the cells are chromophobic, but a few basophils and acidophils have been recognized. Two types of basophils have been differentiated, both PAS + ve: one is weakly AB + ve and is grouped in follicles
sometimes associated with accumulation of intercellular PAS + ve colloid (Olsson, 1959), and with cytoplasm rich in SS/SH groups (Adam,
1963). The second basophil stains with AF, forms signet ring cells after
gonadectomy (Olsson et al., 1965), and may be the gonadotrop. Two
erythrosinophil cell types are present, one with fine granulation which
responds to adrenocortical inhibitors, cortisol and thiourea, which may be
the ACTH cell (Olsson et al., 1965) ; and a second with coarser granulation is activated by reserpine treatment, and may secrete prolactin
(Olsson et al., 1965). The predominant cell type in the caudal region is
PAS + ve and is presumed to be the source of MSH, although there is no
evidence for the secretion of this hormone in myxinoids.
The gland in lampreys is organized in a more familiar pattern (Fig.
25B). Key references are Roth ( 1957, 1958), van de Kamer and Schreurs
( 1959), Oztan and Gorbman ( 1960) , Evennett ( 1963) , Larsen ( 1965),
Riihle and Sterba (1966), and BBge (1967). The pars distalis is embedded in connective tissue, which separates it from pars intermedia and
neurohypophysis; this region is divisible into rostral and proximal parts
by analogy with the teleost gland. The posterior pars intermedia is separated from the neurohypophysis only by a vascular plexus.
In the rostral pars distalis are found chromophobes, and basophils
which are PAS + ve, A F + ve, and contain SSlSH groups (Roth, 1957,
1958; van de Kamer and Schreurs, 1959; Uztan and Gorbman, 1960;
Evennett, 1963, Riihle and Sterba, 1966). In various lampreys, these
basophils increase in number and staining affinities at metamorphosis,
when the entire pars distalis may increase in size (Roth, 1957, 1958;
Oztan and Gorbman, 1980; van de Kamer and Schreurs, 1959). Following
metamorphosis these cells exhibit changes which are not easy to interpret,
but which have been taken to indicate a gonadotropic function (van de
Kamer and Schreurs, 1959; Riihle and Sterba, 1966); but these changes
have not always been observed (Evennett, 1963). The electron microscope shows that there are two kinds of basophils in this region, differentiated by granules size ( BBge, 1967).
The proximal pars distalis exhibits acidophils and basophils, but the
majority of cells are chromophobic and appear most active at metamorphosis in Lampetra planeri (van de Kamer and Schreurs, 1959) or during the anadromous migration in L. fluviatilis (Riihle and Sterba, 1966).
J. N. BALL AND BRIDGET I. BAKER
posteriorly, so that the two components here are in contact (Adam, 1960;
Matty, 1960), but this has not been observed by other workers (Olsson,
1959; Gorbman et al., 1963). In the anterior region of the adenohypophysis, most of the cells are chromophobic, but a few basophils and acidophils have been recognized. Two types of basophils have been differentiated, both PAS + ve: one is weakly AB + ve and is grouped in follicles
sometimes associated with accumulation of intercellular PAS + ve colloid (Olsson, 1959), and with cytoplasm rich in SS/SH groups (Adam,
1963). The second basophil stains with AF, forms signet ring cells after
gonadectomy (Olsson et al., 1965), and may be the gonadotrop. Two
erythrosinophil cell types are present, one with fine granulation which
responds to adrenocortical inhibitors, cortisol and thiourea, which may be
the ACTH cell (Olsson et al., 1965) ; and a second with coarser granulation is activated by reserpine treatment, and may secrete prolactin
(Olsson et al., 1965). The predominant cell type in the caudal region is
PAS + ve and is presumed to be the source of MSH, although there is no
evidence for the secretion of this hormone in myxinoids.
The gland in lampreys is organized in a more familiar pattern (Fig.
25B). Key references are Roth ( 1957, 1958), van de Kamer and Schreurs
( 1959), Oztan and Gorbman ( 1960) , Evennett ( 1963) , Larsen ( 1965),
Riihle and Sterba (1966), and BBge (1967). The pars distalis is embedded in connective tissue, which separates it from pars intermedia and
neurohypophysis; this region is divisible into rostral and proximal parts
by analogy with the teleost gland. The posterior pars intermedia is separated from the neurohypophysis only by a vascular plexus.
In the rostral pars distalis are found chromophobes, and basophils
which are PAS + ve, A F + ve, and contain SSlSH groups (Roth, 1957,
1958; van de Kamer and Schreurs, 1959; Uztan and Gorbman, 1960;
Evennett, 1963, Riihle and Sterba, 1966). In various lampreys, these
basophils increase in number and staining affinities at metamorphosis,
when the entire pars distalis may increase in size (Roth, 1957, 1958;
Oztan and Gorbman, 1980; van de Kamer and Schreurs, 1959). Following
metamorphosis these cells exhibit changes which are not easy to interpret,
but which have been taken to indicate a gonadotropic function (van de
Kamer and Schreurs, 1959; Riihle and Sterba, 1966); but these changes
have not always been observed (Evennett, 1963). The electron microscope shows that there are two kinds of basophils in this region, differentiated by granules size ( BBge, 1967).
The proximal pars distalis exhibits acidophils and basophils, but the
majority of cells are chromophobic and appear most active at metamorphosis in Lampetra planeri (van de Kamer and Schreurs, 1959) or during the anadromous migration in L. fluviatilis (Riihle and Sterba, 1966).