7. THE ULTIMOBRANCHIAL GLANDS
393
shown in Table IV. Removal of the corpuscles of Stannius caused an even
more marked hypercalcemia. This was associated with increased basophilia of the cells in the ultimobranchial resulting from increased RNA,
suggesting increased secretory activity. They also observed that the
stanniectomized eels no longer responded to injections of exogenous
porcine calcitonin and suggested that this might result from the presence
of excess amounts of endogenous hormone. These experiments must be
repeated when a sensitive immunoassay for fish calcitonin makes it
possible to measure hormone levels in blood.
IV. CORPUSCLES OF STANNIUS
The corpuscles of Stannius will be mentioned briefly here, because
they also appear to be implicated in calcium regulation in teleosts. They
arise in holosteans as budlike evaginations from the wall of the pronephric
duct anterior to the opisthonephros. In teleosts, they develop from the
posterior region of the opisthonephros (Hoar, 1957). In goldfish, trout,
and salmon, they are bilateral flat white ovoid structures lying on the
peritoneal surface of the kidney. The gland has a fibrous capsule and is
composed of short columnar cells packed in ovoid or columnar groups.
Under the electron microscope, Ogawa (1967) observed that the cells
contained a well-developed endoplasmic reticulum and a few small mitochondria. The secretory granules appeared to be proteinaeeous. Heavy
granulation was observed after transfer of the fish to one-third seawater,
while hypophysectomy led to a reduction in the granules. Contrary to
earlier speculations, the glands are not related to the adrenals or interrenals (Garrett, 1942) and do not have the capacity to synthesize adrenocorticosteroids (Chester Jones et al., 1965). The function of the corpuscle
of Stannius is obscure and no hormone has been isolated from it, although
it does have the appearance of an endocrine gland.
Fontaine (1964) suggested that the glands might be involved in ion
regulation and observed that removal from the European eel, AnguiZla
unguilla, resulted in a rise in plasma Ca (141%) and K (124%) and a fall
in plasma Na (25%) 1 month after the operation. The changes in Na and
K are similar to those which occur after adrenalectomy in mammals. In
later experiments, he also observed a fall in plasma phosphate in the
stanniectomized eels (Fontaine, 1967). As shown in Table IV, Chan
(1969) also obtained a significant rise in plasma Ca in Anguilla juponicu,
and Ogawa (1968) observed similar changes in stanniectomized goldfish,
Carassius uuraturr. In the latter, the hypercalcemia following stanniectomy
was abolished by administration of angiotensin 11.
393
shown in Table IV. Removal of the corpuscles of Stannius caused an even
more marked hypercalcemia. This was associated with increased basophilia of the cells in the ultimobranchial resulting from increased RNA,
suggesting increased secretory activity. They also observed that the
stanniectomized eels no longer responded to injections of exogenous
porcine calcitonin and suggested that this might result from the presence
of excess amounts of endogenous hormone. These experiments must be
repeated when a sensitive immunoassay for fish calcitonin makes it
possible to measure hormone levels in blood.
IV. CORPUSCLES OF STANNIUS
The corpuscles of Stannius will be mentioned briefly here, because
they also appear to be implicated in calcium regulation in teleosts. They
arise in holosteans as budlike evaginations from the wall of the pronephric
duct anterior to the opisthonephros. In teleosts, they develop from the
posterior region of the opisthonephros (Hoar, 1957). In goldfish, trout,
and salmon, they are bilateral flat white ovoid structures lying on the
peritoneal surface of the kidney. The gland has a fibrous capsule and is
composed of short columnar cells packed in ovoid or columnar groups.
Under the electron microscope, Ogawa (1967) observed that the cells
contained a well-developed endoplasmic reticulum and a few small mitochondria. The secretory granules appeared to be proteinaeeous. Heavy
granulation was observed after transfer of the fish to one-third seawater,
while hypophysectomy led to a reduction in the granules. Contrary to
earlier speculations, the glands are not related to the adrenals or interrenals (Garrett, 1942) and do not have the capacity to synthesize adrenocorticosteroids (Chester Jones et al., 1965). The function of the corpuscle
of Stannius is obscure and no hormone has been isolated from it, although
it does have the appearance of an endocrine gland.
Fontaine (1964) suggested that the glands might be involved in ion
regulation and observed that removal from the European eel, AnguiZla
unguilla, resulted in a rise in plasma Ca (141%) and K (124%) and a fall
in plasma Na (25%) 1 month after the operation. The changes in Na and
K are similar to those which occur after adrenalectomy in mammals. In
later experiments, he also observed a fall in plasma phosphate in the
stanniectomized eels (Fontaine, 1967). As shown in Table IV, Chan
(1969) also obtained a significant rise in plasma Ca in Anguilla juponicu,
and Ogawa (1968) observed similar changes in stanniectomized goldfish,
Carassius uuraturr. In the latter, the hypercalcemia following stanniectomy
was abolished by administration of angiotensin 11.