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Notes on the adrenal of the sloth.

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NOTES ON T H E ADRENAL OE’ T H E SLOTH1
F. A. I-IARTMAN
Department of Physiology, The Ohio S t a t e University, Columbus and
T h e Canal Zone Biological Area
TWELVE FIGURES
INTRODUCTION
The sloth because of its peculiar habits and low rate of
metabolism has engaged the interest of many biologists.
Wislocki ( ’28) published an extensive report on its anatomy in
which he briefly described the adrenals, pointing out that
they lie high in the abdomen near the coeliac axis. Britton
(’41) gave the relative weights of the adrenal in one specimen of Cholepus and two specimens of Bradypus. Carneiro
( ’53) reported on the histology of the adrenals in 4 specimens
of Brndypus griseus.
I n recent years we have studied the adrenals from Cholepus
li,o,@mami and Bradypus griseus collected in Panamb.
METHODS
Body weights were obtained by means of a Chatillon spring
balance and adrenal weights on a Roller-Smith precision balance. The adrenals were fixed in Helly’s solution, and some
in addition with 2% osmium tetroxide after washing away
Helly’s solution. All were cut from paraffin at 5 p and
stained with Masson’s trichrome stain.
OBSERVATIONS
The body weight of the sloth includes stomach contents
which are considerable since this organ always appears to be
Aidrd by grants from the Comly Fund and the Graduate School of Ohin State
Unirersity.
105
106
F. A. HARTMAN
full. In tlircc spccirmns the body weight and stomach contents were respoctivcly : 5150 gm - 900 gm; 5100 gm -- 800
g m ; 3850 gm - 450 gm. Ilowevcr, in our calculations all
values incluclc stomach contents.
The adrenals of seven adult female Cholepus hofwzani were
0.0006 % of the body (body, 2950--5150 gm) and of
0.014 I
10 male adults of the same species were 0.016 A 0.0006% of
the body (body, 2250-5200 gm). The adrciials of young animals were proportionately greater, viz., 450 gm male 0.06680/0, 523 grn female - 0.058%, 700 g m female -- 0.048'%,
1070 gm male - 0.0252% and 1600 gm female - 0.0249%.
The adrenals of Brndypus griseus showed greater variation. The values for 5 females were: Lody, 3850 gm-aclrenals, 0.006070 ; body, 3300 gm - adrenals, 0.0075% ; body
3300 gm - adrenals, 0.0092% ; body, 3130 gm - adrcnnls,
0.01057, ; lrody, 1650 gm - adrenals, 0.0141%. Three males
were likewise variable : body, 4400 gm - adrenals, 0.0089% ;
body, 3850 gm - adrcnals, 0.00949, and body, 2650 gm - adrenals, 0.01 67%.
The cliangcs in form, relative size and position of the
adrenal during the developrrierit of the young animal a r c
vc1.p striking. I n the fetus at one stage it is larger than
tlw Ititlney ant1 in apposition to its anterior pole. A t this time.
it may be irregularl>-ellipsoid in form (fig. 1 ) . Later it heyiiis
to rcccde from the kidney a i d changes to ovoid in shape (fig.
2). It soon hecorncs very much elongated (fig. 3 ) and a f t e r
this moves much farther away from the kidney (fig. 4) until
it lies at a considerahlc distance anteriorly (fig. 5). (Vnfortunately, thcsc drawings a r e not proportionate to each
other.) I n the adult its relation to other structures is shown
in figure 6. The anterior location makes adrenalectomy difficnlt. S o far as we know, no one has successfully removetl
thc aclrenals from the sloth so that the operation itself was
not a large factor in the early death. Brittori stated that
ntlrcnalectomy resulted in death usually within 24 hour.:
which ohvionsly may have been due to the opei-ation per w.
zStaiidnrd error of the mcan.
SLOTH AURENALS
107
Histology
We have examined the adrenals from 38 Cholepus and 9
Bradypus. There was no great difference between the adrenals
of the two species.
With Masson’s stain, threc areas stand out; the lighter
gloinerulosa and medulla and the darker fasciczilata and
rcticularis (fig. 7).
There is a loose covrring of connectivc tissue with a thick
capsule, the connective tissue of which extends between the
coils of cells composing thc glomerulosa (fig. 8).
The most important features of the sloth adi-cnal arc the
large amount of connective tissue within the gland and the
distinctive structurc and staining properties of the glomerulosa. I n some instances, connective tissue, completely surrounds the glomerular “islands,” but whether it does or not,
the arrangement and shape of the cclls is so different that one
can easily distinguish this zone in the adult (fig. 8). The cells
may appear as spheroidal groups or elongated groups as
though pullpd toward the gland’s centcr (fig. 9). Thc glomerulosa is composed of fairly large cells grouped around a
central axis. Thc fasciculata is made up of rather indistinct
columns composed of cclls somewhat smaller than those of
the glomcrulosa. Tlic rcticularis cxcept for the greater irregularity in cell arrangement differs little from the fasciculata (fig. 8). Transition from tlic fasciculata to the reticularis is shown in figure 11. Much connective tissue lies hetween the reticularis and medulla in some regions, cortical
cells bcing scattered through it in diminishing numbers as
they approach the medulla.
Thc medulla consists of distinct clusters of large cclls, the
clusters varying greatly in size. These cells tend to be grouped
around a ccntral axis, (fig. 12).
I n staining, as already mentioncd, thc glomerulosa was distinctly lighter, and of a somewhat different color with hfasson.
It was also lighter with osmium tctroxide.
The adrenals of one 525-gm young Cholcpus were examined.
The glomerulosa was indistinct (fig. 10). In an animal some-
10s
F. A. HARTMAN
what older (700 gm) the glomerulosa could be seen although
not as wcll marked a s in the adult.
Outstanding in the adult is the striking contrast of the
gloincrulosa whose cell shape, arrangement, separation and
difference in staining reaction from the rest of the cortex suggest a distinct, independent zone.
L I T E R A T U R E CITED
BRITTON,
S. W. 1941 Form and function in the sloth. Quart. Rev. Riol., 1 6 :
190-20 7.
CARNEIRO,J O S C 1953 Histology and histochemistry of the adrenal of the sloth
(Brad?jpus trrtlactylus). An Acad. Brasil Cibnc., 2 5 : 309-317.
WISLOCKI,G. B. 1928 Observations on gross and inicroscnpic anatomy of slothq
(Bradypus griseus and Cholepus hoffmanz). J. Morphol. Physiol.,
46': 317-397.
PLATE 1
EXPLANATION OF FIGURES
Changes i n Cholepus hoffmani at different ages.
1 Adrenals of 97-gm female fetus.
2
Adrenals of 300-gm male fetus.
3
Adrenals of 498-gm young male.
4
Adrenals of 2275-gm young male.
5
Adult.
PLATZ 1
1
2
4
109
‘3
I’LATE 2
EXPLANATION OF FIGURE
6 Adreiials of adult (Cholcpus koffmani) showing rclation t o other structures.
PLATE a
11 I
PLATE 3
EXPLANATION O F FIGURES
All figures are unretouched photomicrographs of sections of the adrenal gland.
7
Longitudiiial section showing general topographical features, Cholcpus h o f man4 Masson stain. X 40.
8 Field from lorigtiudiiinl section. Glomerular islands with fasciculntn merging
into the reticulariq. Bmclypus grzscus, Masson stain. X 100.
9
Field froin longituclinal section from a different animal showing glomerular
islands and characteristic arrangement of cells. Bradyptca griscus, Masson
stain. X 440.
10
Field from cross sectio~inf adreiial of young animal (450 gm) showing
relative lack of zonation. Cholcpus hoffmani, Masson stain. X 100.
1 1 Field from cross section of adrenal from adult showing fasciculata above,
retieulnris below. B r a d y p u s griseus Masson stain. X 440.
12
Field from longitudinal section from adult animal showing groups of cells
in the medulla. Cholepus hoffmanz Mnsson stain. X 440.
1.7 a
7 13
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