The Endocrine System

448 Pages·1969·9.618 MB·English

by  W.S. Hoar and D.J. Randall (Eds.)

FISH PHYSIOLOGY
Edited by
W. S. HOAR
DEPARTMENT OF ZOOLOGY
UNIVERSITY OF BRITISH COLUMBIA
VANCOUVER, CANADA
and
D. J. RANDALL
DEPARTMENT OF ZOOLOGY
UNIVERSITY OF BRITISH COLUMBIA
VANCOUVER, CANADA
Volume 11
The Endocrine System
@
Academic Press New York and London 1969
COPYRIGH@T 1969, BY ACADEMICP RESSI,N C.
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LIST OF CONTRIBUTORS
Numbers in parentheses indicate the pages on which the authors' contributions begin.
BRIDGETI. BAKER( l),D epartment of Zoology, University of Liverpool,
Liverpool, England
J. N. BALL ( 1, 207, 321), Department of Zoology, University of Shejgield,
Sheffield, England
HOWARD A. BERN (3!39), Department of Zoology and Cancer Research
Genetics Laboratory, University of California, Berkeley, California
D. K. 0. CHAN"( 321), Department of Zoology, University of Shejgield,
Shef ield, England
I. CHESTEJRO NES (321), Department of Zoology, University of Shefield,
Shffield, England
D. HAROLD COPP( 377), Department of Physiology, University of British
Columbia, Vancouver, Canada
AUGUSTE PPLE( 275), Daniel Baugh Institute of Anatomy, Thomas Jef-
ferson University, Philadelphia, Pennsylvania
AUBREYG ORBMAN( 241), Department of Zoology, University of Washing-
ton, Seattle, Washington
I. W. HENDERS(3O2N1 ), Department of Zoology, University of S w l d ,
Sheffield, England
A. M. PERKS( lll),D epartment of Zoology, University of British Colum-
bia, Vancouver, Canada
'
Present address: Department of Zoology, University of Hong Kong, Hong Kong.
V
PREFACE
Volume I of this treatise is devoted to osmotic and ionic regulation,
the physiology of excretion, and certain aspects of fish metabolism. The
endocrinology of fishes is considered in Volume 11. Few fields of animal
physiology have expanded more rapidly during the past decade.
The publication in 1957 of “The Physiology of the Pituitary Gland of
Fishes” (New York Zoological Society) by Grace E. Pickford and J. W.
Atz provided a detailed bibliography and review of all the significant
earlier work on the endocrinology of fishes; the authors of this compre-
hensive book dealt not only with the pituitary but with other endocrine
systems related to it. The intervening years have seen intense research in
fish endocrinology, resulting in numerous monographs and reviews de-
voted to particular subjects and increasing numbers of fish papers in
General and Comparative Endocrinology which first appeared in 1961.
New factors, such as some of the neurohypophysial hormones, have been
discovered in previously known endocrine organs; additional functions,
such as those of prolactin, have been described for previously known
hormones; new hormones, such as calcitonin, have been recognized in tis-
sues (the ultimobranchial glands) which only a decade ago were not
accepted as endocrine organs. This has been an exciting period in com-
parative endocrinology, and the aquatic vertebrates with their vast range
of specialized functions have held the key to several sigdicant discov-
eries-particularly those of phylogenetic interest.
We originally planned to include all of fish endocrinology in Volume
11. However, this has proved impossible because of the length of the
contributions and, more particularly, because of the space (which we
consider justiiied) that has been devoted to the pituitary gland. Conse-
quently, the physiology of reproduction will appear in Volume I11 and
the physiology of the pineal gland will be discussed in Volume IV. The
actions of transmitter substances are not dealt with separately but will
be found in several volumes where their effects on different organ sys-
tems are described. We hope that Volume I1 will prove particularly valu-
able to fish endocrinologists and that it will also find an important place
in the literature of comparative physiology and endocrinology.
July, 1969 W. S. HOAR
D. J. RANDALL
vii
1
THE PITUITARY GLAND: ANATOMY AND
HISTOPHY SIOLOGY
J. N. BALL AND BRIDGET I. BAKER
I. Introduction . . . . . . . . . . . . 1
A. The Pituitary Gland in General . . . . . . . 1
. .
B. Adenohypophysial Histophysiology and Cytophysiology 2
11. The Pituitary Gland in Teleosts . . . . . . . . 4
A. General Organization . . . . . . . . . 4
B. Histophysiology of the Adenohypophysis . . . . . 9
C. The Neurohypophysis in Teleosts . . . . . . 58
D. Blood Supply to the Teleostean Pituitary . . . . . 67
. . . .
E. Hypothalamic Control of the Adenohypophysis 70
111. The Pituitary Gland in Primitive Bony Fishes . . . . . 74
A. Superorder Chondrostei . . . . . . . . . 74
. . . . . . . . .
B. Superorder Holostei 78
IV. The Pituitary Gland in Lungfishes . . . . . . . 81
V. The Pituitary Gland in Elasmobranchs . . . . . . 83
VI. The Pituitary Gland in Cyclostomes . . . . . . . 89
Acknowledgments . . . . . . . . . . . 93
References . . . . . . . . . . . . . 93
I. INTRODUCTION
A. The Pituitary Gland in General
In all vertebrates, the pituitary gland or hypophysis consists of two
parts, separable on the bases of embryology, structure, and function.
These are the neurohypophysis, a downgrowth from the floor of the
diencephalon, and the adenohypophysis originating as an ectodermal up-
growth (Rathke’s pouch) from the roof of the embryonic buccal cavity
(Wingstrand, 1966a). The two parts meet and enclose between them a
mesodermal rudiment which gives rise to their intrinsic blood vessels
1
2 J. N. BALL AND BRIDGET I. BAKEX
(Green and Maxwell, 1959; Green, 1966). Thus the gland is a composite
organ, and it has many different endocrine functions.
The adenohypophysis is the site of synthesis, storage, and release into
the blood of several different peptide hormones; and the greater part of
pituitary histophysiology is concerned with the allocation of each of these
hormones to the type of pituitary cell that secretes it. The adenohy-
pophysis is divided into the pars distalis, site of secretion of most adeno-
hypophysial hormones, and the pars intermedia. The neurohypophysis
in fishes is rather simpler than in land vertebrates ( Wingstrand, 1Wa)
and consists essentially of a hypophysial stalk, suspending the gland from
the ventral region of the diencephalon (hypothalamus) and containing
an extension of the third ventricle (infundibular recess), and at the distal
end of the stalk an enlargement, the neurohypophysial lobe or core,
which forms the middle of the gland (Figs. 1 and 2). The stalk contains
the axonal fibers of neurosecretory cells, the cell bodies being located in
the hypothalamus. The neurohypophysial core consists largely of the end-
ings of these fibers interspersed with cells termed “pituicytes.” The neuro-
hypophysis seems to be in general a storage-release center for materials
which are actually synthesized in the hypothalamus and then transported
to the neurohypophysial core along the neurosecretory axons (Section
11, C). In many fishes, the neurohypophysial stalk is virtually absent, the
pituitary then being pressed close to the ventral surface of the hypothala-
mus, while in a few teleosts (e.g., Lophim) the neurohypophysial stalk
is extremely long ( Wingstrand, 1966a).
B. Adenohypophysial Histophysiology and Cytophysiology
Purves (1966) has usefully divided the cytological criteria used in the
study of the adenohypophysis into two groups. The first category consists
of features that are indicators of the specific nature of the functions of
individual cell types such as granule size, staining reactions and chemical
nature, cell morphology, and reactions to specific physiological altera-
tions; these features are the data of special cytology, which is particularly
concerned with allocation of function to each cell type. The second cate-
gory includes those features which are indicators of the functional state
of the cell, indicating high or low rates of metabolic or secretory activity
such as nuclear size, nucleolar size, amount of cytoplasmic RNA, state of
the Golgi apparatus, and accumulation or loss of secretory granules.
These features constitute the field of general cytology. In the study of
fishes, as in other vertebrate groups, workers on the pituitary have been
concerned with both kinds of criteria. However, more than in the highly
worked field of mammalian pituitary histophysiology, most investigations
1. THE PITUITARY GLAND 3
on fishes are still primarily concerned with special cytology. This implies
that there is, as yet, no complete general agreement about the functions
of the various types of cell distinguishable in the fish pituitary; although
perhaps with the greater technical standardizations that have come about
in recent years, especially the use of methods developed in mammalian
studies by Herlant (1956, 1960), and first applied to the fish pituitary by
Olivereau and Herlant ( 1954, 1960), the actual morphological and tinc-
torial characteristics of the teleostean adenohypophysial cell types would
now be agreed upon by most workers. However, there is still disagree-
ment about the functions of these cell types since the experimental allo-
cation of function to the cells has been attempted systematically in only
a few species. It follows that not all workers in this field would agree on
a generally applicable functional nomenclature of cell types. In this re-
view, the nomenclature used is the one established partly on functional
and partly on tinctorial grounds following experimental studies in the
eel, Anguilh, and the molly, Poecilia (Olivereau, 1963b; Olivereau and
Ball, 1964). It is a mixed nomenclature, in Purves’ terms (1966), based
partly on similarities in staining properties of the secretory granules to
those in mammalian cells of demonstrated function but mainly (pri-
marily) on the characteristic responses of the cells in fishes to experi-
mental situations designed to alter the secretion rates of the different
adenohypophysial hormones. Logically, one is on equivocal ground in
applying this nomenclature to species in which such experimentation
has not been performed. But in the teleosts, which include the vast ma-
jority of fishes, the distribution of cell types within the adenohypophysis
is extremely regular so that to a far greater extent than in other verte-
brate groups the topographical location of a cell type can support its
identification on tinctorial grounds. Nevertheless, it must be recognized
that the extension of Olivereau’s mixed nomenclature to all teleosts would
not yet be accepted by all workers on the fish pituitary, and the reader
new to this field should bear this in mind. It seems to us that the alterna-
tive, to perpetuate yet another purely numerical or Greek letter morpho-
logical system, would present further opportunities for the extension to
fishes of the nomenclatural confusions that are rife in pituitary studies on
higher vertebrates (see Herlant, 1964; Purves, 1966). We think that tinc-
torial and locational grounds alone are usually sufficiently certain criteria
for the extension of the Olivereau nomenclature from those fishes in which
it has an experimentally defined functional basis ( Anguillu, Poecilia, and
Mugi2 and for certain cell types a few other species) to the vast majority
of teleosts in which the desirable experimental backing is lacking. Un-
fortunately, there are almost no certain grounds for extending the system
to nonteleostean groups.
Frequent reference will be made to the staining properties of the cells.
4 J. N. BALL AND BRIDGET I. BAKER
By this is always meant the staining properties of the specific secretory
granules elaborated and stored within the cytoplasm. The background
colorations of the cytoplasm, or of other inclusions such as lysosomes, are
not relevant to the tinctorial classification of pituitary cell types. Since it
is obvious and readily demonstrable that the method of fixation can
greatly influence the reactions of every type of cell to standard staining
techniques (see Racadot, 1963a; Schreibman, 1964), and since the affinity
of the secretory granules for the various dyes in common use will be
affected by the staining procedure applied, wherever possible the cell
types will be described from material fixed in sublimated Bouin-Hollande
(Herlant, 1956; Kraicer et al., 1967) and stained by the various proce-
dures introduced by Herlant (1956, 1960; Kraicer et al., 1967), in par-
ticular Herlant’s Alizarin blue tetrachrome ( Aliz B ) , periodic acid-Schiff
with orange G (PAS-OG), and the combination oxidation-Alcian blue-
PAS-orange G ( Ox-AB-PAS-OG). The central role played by the PAS
procedure in pituitary studies has often been emphasized (Herlant, 1964,
1965; Purves, 1966): In essence, this technique distinguishes cells with
glycoprotein-containing granules ( PAS positive ) from cells with nongly-
coprotein granulation ( PAS negative ) , a distiixtion approximately cor-
responding to the older division between basophils and acidophils and
+
often marked by the terms “mucoid cells” (PAS ve) and “serous cells”
(PAS - ve). The importance of this distinction for pituitary studies
stems from the chemical information we have about the various hormones
extracted from mammalian pituitary glands, some of which are glyco-
proteins [gonadotropins, follicle-stimulating hormone (FSH), luteinizing
hormone (LH), and thyrotropin or thyroid-stimulating hormone (TSH)]
while others are peptides or proteins with no carbohydrate moiety [pro-
lactin, somatotropin (STH) or growth hormone (GH); corticotropin,
adenocorticotropin or adrenocorticotropic hormone ( ACTH ) ; and inter-
medin or melanophore-stimulating hormone ( MSH ) ]. Another important
technique is aldehyde fuchsin ( AF ) , usually preceded by oxidation,
which has a less secure histochemical basis ( Herlant, 1965).
11. THE PITUITARY GLAND IN TELEOSTS
A. General Organization
The organization of the teleostean gland has been the subject of many
reviews (e.g., Pickford and Atz, 1957; Olivereau, 1954, 1963b; Stahl,
1963; Wingstrand, 1966a), and we shall concern ourselves mainly with
1. THE PITUITARY GLAND 5
the more recent information. The anatomy of the gland at first sight ap-
pears almost as varied as the teleosts themselves, but closer examination
shows that this superficial variety can be reduced to a common anatomi-
cal and histological pattern. A species in which the histophysiology of
the pituitary has been particularly fully investigated is the European eel,
Anguilla anguilla, in a long series of fundamentally important studies by
Olivereau. The gland has also been investigated in the cyprinodont
Poecilia lutipinna and P. formosd by the senior author and his collabora-
tors. A description of the gland in these two teleosts will serve as a basis
for a general account of the teleostean pituitary, and notable departures
from these basic types will then be considered.
1. THEE EL, AnguiZZa anguilla
Olivereau ( 1967a ) has recently summarized her extensive experimen-
tal investigations of the eel pituitary (Fig. 1).T he two primary divisions
of the gland are obvious, with the central neurohypophysis interdigitating
with the shell-like adenohypophysis. The adenohypophysis may be fur-
ther divided into two main parts: anteriorly the pars distalis, subdivided
into rostral and proximal pars distalis, on the basis of cell types; and
posteriorly a pars intermedia. As usual in teleosts, the interdigitations of
the neurohypophysis with the pars intermedia are particularly deep and
elaborate, while the neurohypophysial-pars distalis interdigitations are
less pronounced.
The terminology applied to the fish pituitary was for many years in
a state of confusion, and a new terminology introduced by Pickford and
Atz (1957) helped to introduce some uniformity. On this scheme the
rostral pars distalis was termed the “pro-adenohypophysis,” the proximal
pars distalis was termed the “meso-adenohypophysis,”a nd the pars inter-
media was termed the “nieta-adenohypophysis.”A t the time they were
introduced these terms were valuable in preventing the too easy assump-
tion of the functions of the various regions implicit in applying the mam-
malian terms “pars distalis” and “pars intermedia” to the fish gland. How-
ever, advances in our knowledge of the functions of the various cells in
the teleost gland during the past 10 years or so have rendered this termi-
nology in some respects misleading. Current evidence, reviewed below,
implies that the pro- and meso-adenohypophysis together form the func-
tional equivalent of the tetrapod pars distalis, and the meta-adenohy-
pophysis is equivalent to the pars intermedia; this being so, there is no
reason to accord each of these three regions in the teleost gland equal no-
* Throughout this review, any observations on Poecilia quoted without references
come from unpublished work by J. N. Ball and collaborators.
J
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