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The Internal Anatomy
of the Thylacine - A Historical Perspective
Professor Daniel
John Cunningham (continued): |
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| Diagram
of the thylacine heart and lungs. After Cunningham (1882). |
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| Cunningham proceeds
to make observations on the trachea and lungs. He notes that the
trachea of the specimen he was dissecting is 17 cm (6¾ in.) in length
and is comprised of 34 cartilaginous rings, which are deficient superiorly
throughout its entire length. He observes that the left lung is undivided
by any marked fissure with a deeply crenated or scalloped margin and that
the right lung is divided into three lobes and rests by its base upon the
upper surface of the diaphragm. |
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Heart and lungs of Thylacinus.
Specimen 120706.
Courtesy: Hunterian Museum
(Glasgow). Source: ITSD 5th Revision 2013.
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Cunningham then turns his attention to the examination of the abdominal
viscera, and writes that the stomach of the thylacine has a close resemblance
in appearance to that of man. The curvatures however, are more pronounced,
and the transition from the wide cardiac portion of the stomach to the
narrow pyloric part more sudden, with the fundus rising high above the
cardiac opening. Cunningham provides detailed measurements of the
stomach obtained from the female specimen, and then proceeds to discuss
its internal structure. He states that the intestinal canal of the
thylacine is remarkably short, and shows no differentiation into large
and small intestine. The calibre (diameter) of the intestinal canal
is to a great degree uniform throughout its entire length. Cunningham
notes the length of the intestine for the male specimen as being 195.58
cm (6 ft. 5 in.); and for the female specimen 142.24 cm (4 ft. 8 in.).
He observes that in the anterior part of the intestine, the villi are filamentous
in shape and about 1.27 cm (½ in.) long. They are arranged |
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| Illustration
of the thylacine's gut by Chalmers Mitchell (1916), who writes: "In
the Thylacine... the pattern does not differ in any important respect from
that of Notoryctes [marsupial mole], there being no caecum and the
three regions of the gut not being sharply marked off, although the grouping
of the tributaries of the mesenteric vein suggests their presence.
The calibre of the whole gut is rather large and approximately the same
throughout. The subsidiary coils of the proximal portion of Meckel's
tract are rather more numerous than is represented in the figure". |
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sparsely over the mucosal surface, giving
it a rough, shaggy appearance. As one progresses down the intestine
the appearance of the villi change as they gradually become stouter and
more club-shaped, and finally stunted and conical
before disappearing some 40.5 cm (16 in.) before the anal opening.
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| Click
the microscope icon for a magnified view of: filamentous
intestinal villi (Thylacinus). |
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| Click
the microscope icon for a magnified view of: stunted
and conical villi (Thylacinus). |
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The alimentary tract
of the thylacine.
1. Oesophagus, 2. Fundus, 3.
Cardiac sphincter, 4. Stomach, 5. Pyloric sphincter, 6. Intestine, 7. Anus.
Courtesy: National Museum
of Australia. Source: ITSD 5th Revision 2013. |
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Cunningham notes that the gut of the thylacine was richly supplied with
Peyer's
patches, the largest of which commenced about 40.5 cm (16 in.)
from the anal opening and advanced along the gut some 57 cm (22½
in.) in the male specimen and 35.5 cm (14 in.) in the female specimen.
Peyer's
patches are a collection of large, oval-shaped lymph tissues
that are located in the mucus-secreting lining of the small intestine.
These lymph nodules are especially abundant in the ileum, the lowest portion
of the small intestine. The Peyer's patches contain high concentrations
of white blood cells (or lymphocytes) that help protect the body from infection
and disease.
| Click
the microscope icon for a magnified view of: Peyer's
patches. |
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With reference to the
spleen, Cunningham observes that it is an elongated tongue-like structure
placed obliquely across the abdomen, and that a small finger-like extension
protrudes from the right side of the body of the spleen and projects towards
the kidney. Cunningham notes that the pancreas is well developed
and that the liver is divided into right and left segments, with the left
segment being smaller than the right and showing no sign of sub-division
into lobes. A central cleft divides the right segment of the liver
into two equally sized lobes. The kidneys present the usual reniform
outline with a small and constricted sinus. In section, the medullary
substance was uniform with a thin cortex. The bladder, which he observes
was in a contracted state, was remarkable for its small size; not larger
than a small walnut. In shape, it was ovoid with thick muscular walls. |
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| Thylacine
spleen (specimen RCS A116.1) dissected by Dr. Edwards Crisp. Courtesy:
Royal College of Surgeons (England). Source: ITSD 5th Revision 2013. |
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| Cunningham
concludes with his observations on the genitourinary system of the male
and a description of the marsupium of the female specimen. He was
unable to make any comment on the female reproductive tract as the specimen
in his possession had been damaged. To this day, Cunningham's work
has not been equalled and forms the core of our knowledge on the thylacine's
internal anatomy.
The remains of the skeletal
and soft tissue parts from both of the Challenger thylacines are now preserved
in the collection of the Natural History Museum in London (Source: ITSD
5th Revision 2013). |
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| Thylacine
kidney (specimen: AMNH 200334). Courtesy: American Museum of Natural
History. Source: ITSD 5th Revision 2013. |
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