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Physiological marrow ossification in female pigeons.

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PHYSIOLOGICSL MARROW OSSIFICATION I N
F E M A L E PIGEONS
PRESTON RYES A S D TRUMAN S. POTTER'
Laboratory of Preventive Nedicine, The DTLiversity of Chicago
Structural changes occur in the bone marrox of female
pigeons which are not fonnd in the male. Such changes are,
essentially, variations in ossification of thc marrow and arc
coincident with changes in the ovary.
Our observations mere made npon the red r ~ i a r r oof~ the
long bones of the leg and extending over a period of 2 years
relate to 850 pigeons-449 male a i d 401 female. Obseruations
were made in all months of the %year period.
By gently splintering the shaft o€ the femur freshly removed form a male pigeon, thc marrow may be exposed in
sitn as a dark red, moist, pulpy cord completely filling the
mcdullary cavity. KO appreciable attachmcni of this cord to
the inner surface of the shaft exists and the marrow may be
removed in toto, exposing the inner surface of the bone a s
smooth and glistening. This condition is constant for all male
pigeons.
Tn sharp contrast to the uniformity of the marrow pattern
thus presented in the male is the extreme individual variation
seen in the female. For although a considerable number of
females killed a t random present a marrow pattern indistinguishable from that of the male, an equal number show an
ossification of the marrow. Histologically, this is a true ossification displaj-ing lamellation and haversian canals. The
degree of ossification in the female differs markedly in individual instances. In certain females it is slight and is limited
Seymour Conian Fellow of Preventive Meclicine.
377
THE ANATOIIICAL RECORD. V O L . 6 0 , NO.
NOVEMBER, 1934
4, AND
SUPPLEMZNT
378
PRESTOIS IEYFS AND TRUMAN S. POTTER
t o delicate spicules of bone extending from the inner surface
of the shaft a short distance into the marrow. I n such
instances the removal of the marrow exposes the wall of the
medulla as a rough granular surface in contrast t o the smooth
glistening surface seen in the male.
In certain other females delicate trubeculae of bone extend
well into the marrow and the marrow cannot be stripped from
the medullary canal. With this medium degree of ossification,
the marrow remains moist artd of dark red color.
I n those females where tlhe ossification is maximal, anastomosing trabeculae of bone extend in every direction througout the medulla, the marrow proper being enmeshed in the
interstices of the bony network. The marrow is relatively dry,
its color is gray and the texture is chalky.
While for convenience in description the above degrees of
slight, medium, and extreme ossification are cited, all intermediate degrees of ossification occur with the shading of the
one group into the next.
Of the 449 males observed, none showed a marrow ossified
in any degree. Of the 401 females observed, 215 showed
marrow without ossification ; 112 showed slight o r medium
marrow ossification and 74 c;howed extreme ossification.
The fact that the bone marrow of female pigeon undergoes
osseous modifications which do not occur in the male is of
less import than the fact that these changes are cyclic and
parallel functional changes of the ovary. The degree of
ossification varies directly with the size of the developing
ovarian follicles. Thus when the ovary contains no follicle
of a. diameter greater than 2 mm. there is no ossification of
the marrow. Rut when thc ovary contains a follicle of more
than 4.5 mm. in diameter, there is always some degree of
ossification of the marrow and when a 10-mm. follicle is
present there is always extreme ossification of the marrow.
Systematic measurement was made of the diameter of the
largest ovarian follicle found in each of 298 females and
these diameters averaged f o r each of the three groups showing : no ossification, medium ossification and extreme ossi-
MARROW OSSIFICATION IN FEMALE P I G E O N S
379
fication: the mean diameter of the maturest follicle i n those
females with n o marrow ossification was 1.6 mm. ; f o r those
with medium ossification, 4.1 mm. and for those displaying
extreme ossification, 9.1 mm.
W e conclude from these findings that in female pigeons
there is a cyclic ossification of the red marrow of the long
bones of the leg and that the ossification is coincident with
the maturation of the ovarian follicle.
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