Bull Vet Inst Pulawy 49, 323-327, 2005
MORPHOLOGICAL STRUCTURE OF THE SYRINX IN THE
BURSA ROLLER PIGEON
, BESTAMI YILMAZ
AND İLKER ARICAN
Department of Anatomy, Faculty of Veterinary Medicine, University of Uludag, 16059 Bursa, Turkey
University of Harran, 63300 Şanlıurfa, Turkey
Received for publication July 06, 2005.
The aim of this study was to investigate the
topographical, anatomical and histological characteristics of
the syrinx in 18 Bursa Roler Pigeons. The study showed that
the syrinx in pigeons was of tracheobronchial type and was
composed of tympanum, cartilagines tracheosyringeales, and
cartilagines bronchosyringeales. Tympanum and cartilagines
bronchosyringeales were formed from 5 cartilage rings, while
cartilagines tracheosyringeales were formed from 4 C-shaped
cartilage rings. The pessulus was made up of a double-folded
mucous membrane extending dorsoventrally from median
walls of the bronchus primarius into the cavum syringis. The
membrana tympaniformis lateralis filled the distance between
the third and fourth cartilagines tracheosyringeales rings. The
membrana tympaniformis medialis covered the distance
between the medial ends of the cartilagines broncho-
syringeales rings. There were 2 syringeal muscles termed
tracheolateral and sternotracheal. The lamina epithelialis of the
mucosa was lined with non-cornified stratified squamous
Key words: pigeons, Columba livia, syrinx,
The Bursa Roller Pigeon lives in the South
Marmara Region in Turkey. Special attention has been
paid by breeders to protect the pureness of this race.
Important distinguishing feature of this race is their
fastidious vocal organ, called syrinx, allowing them to
produce their special song pattern (20, 13, 15). Its
morphological structure has been investigated in some
bird species. It is located in the terminal part of the
trachea and the first part of the two main bronchi (6, 10,
11, 16, 23, 25). The skeleton of the tracheobronchial
type of the syrinx is composed of 3 different parts, i.e.
tympanum, cartilagines tracheosyringeales (CTS) and
cartilagines bronchosyringeales (CBS) (2, 15, 16, 24).
Two membranes, membrana tympaniformis
lateralis (MTL) and membrana tympaniformis medialis
(MTM), are involved in the formation of sound in the
bird syrinx (13). The sound can be altered by a complex
of extrinsic and intrinsic muscles surrounding the syrinx
(16). The syrinx mucosa consists of either bistratified
squamous (1), columnar (3, 5, 17), or pseudostratified
prismatic epithelium (22).
In our knowledge, up to date no scientific study
has been carried out to characterize the structure of the
syrinx in the Bursa Roller Pigeon. In the present study,
we investigated the topography, anatomy, and histology
of the syrinx in this species. The results of this research
may useful in operations of the syrinx in this species.
Material and Methods
Eighteen (9 male and 9 female) Bursa Roller
Pigeons (Columba livia), which died due to various
causes, were obtained from the South Marmara Region
pigeon raisers. All the pigeons were 2-year-old and had
an average weight of 234.40 ± 11.12 g. Firstly, the body
cavity was opened and the syrinx was observed in the
terminal part of the trachea. After pointing out the
topographic features precisely, sections were made 6 cm
to the dorsal side of the trachea and 4 cm to the ventral
side of the syrinx. The morphological characteristics
were investigated by means of a magnifying glass and
measurements made with a digital compass (Mitutuyo
Corporation, Kawasaki, Japan). For histological
investigation, the tissue was fixed in 10% formalin for at
least 72 h. After routine processing and embedding in
paraffin, 6 µm tissue sections were cut, stained with
haematoxylin and eosin, and 10 µm sections were cut
and stained with Pincus acid orcein-Giemsa for the
demonstration of the elastic fibers surrounding the
cartilages (17). Sections were investigated under a light
microscope (Nikon Optiphot-2, Nikon Corporation
Imaging Company, Japan) and photographed (Nikon
FA-35DX, Nikon Corporation Imaging Company,
Statistical analysis was performed by Minitab
statistical package (for Windows version 11). The
ANOVA was used to investigate comparison of the
For the terminology, the Nomina Anatomica
Avium (14) was used.
The pigeon syringes were observed to lie at the
dorsal side of the glandular stomach, ventrally of the
oesophagus and between the terminal part of the trachea
and bronchus primarius (Fig. 1). On the ventral surface
of the syrinx displayed itself the membrana
tracheosyringealis associated with the thin tympanum
and CTS in the midline. This membrane was not seen on
the dorsal surface of the syrinx. The skeleton of the
syrinx was composed of 3 different cartilage groups.
These were the tympanum, CTS and CBS (Fig. 2). The
results of the measurements of the laterolateral (LLD)
and dorsoventral (DVD) diameters of these parts are
presented in Table 1.
Fig. 1. Ventral view of the syrinx in the pigeon within the body cavity. Syrinx (s),
oesophagus (e), pessulus (p), membrana tympaniformis medialis (m).
Mean laterolateral and dorsoventral diameters of the syringeal cartilages (mm)
First ring Third ring Fourth ring Fifth ring
5.10 ± 0.15
5.53 ± 0.12
3.64 ± 0.11
4.03 ± 0.09
5.67 ± 0.13
5.87 ± 0.15
5.22 ± 0.12
4.33 ± 0.14
5.03 ± 0.14
4.53 ± 0.10
2.36 ± 0.06
1.94 ± 0.06
4.12 ± 0.15
3.25 ± 0.12
* P< 0.05; ** P < 0.001; ± SD.
Fig. 2. Dorsal view of the pigeon syrinx. Tympanum (t), Fifth tympanum ring (t5), cartilago tracheosyringealis 3 (ts3),
cartilago bronchosyringealis (bs), cartilago bronchosyringealis 1 (bs1), membrana tympaniformis lateralis (l),
membrana tympaniformis medialis (m), m. sternotrachealis (st), m. tracheolateralis (tl).
Fig. 3. Histological section of the pigeon syrinx. Non-cornified stratified squamous epithelium (e),
mucous gland (g), lamina propria (lp), elastic fibres (el), hyaline cartilage (h), tunica muscularis (tm).
Pincus acid orcein-Giemsa stained, bar 50 µm.
The tympanum was formed from 5 oval-shaped
cartilage rings pressed dorsoventrally. Because of its
cylindrically formed cartilages, it was different from
CTS. The average length of the tympanum was 4.11 ±
0.09 mm and from cranial to caudal, both LLD and
DVD of these rings were increasing. In fact, the CTS
which are generally known as a part of the tympanum, in
our case appeared as a separate part. Ventral and dorsal
ends of CTS were not joined each other. The
composition of CTS was constituted from four cartilage
rings having an average length of 5.15 ± 0.13 mm. The
CTS were ovally shaped and its LLD were larger than
DVD. But, the diameter of the third cartilage was larger
than that of the fourth cartilage. The largest distance was
1.72 ± 0.06 mm in middle and 2.84 ± 0.09 mm in the
lateral part. The space between the third and fourth ring
was filled by a membrane known as MTL. The CBS
consisted of five C-shaped half-rings and their average
length was 3.39 ± 0.12 mm. Both the LLD and DVD of
these rings decreased caudally. The distance between the
medial ends of the rings also decreased caudally from
3.56 ± 0.17 mm to 2.74 ± 0.16 mm and this distance was
covered by MTM (Fig. 1).
The medial walls of the right and left bronchus
primarius fused at the level of the bifurcatio tracheae
and formed the pessulus, which extended dorsoventrally
as a double-folded mucous membrane (average
dorsoventral length 4.00 ± 0.17 mm). A ligamentum
interbronchiale connecting the right and left bronchus
primarius was not observed (Fig. 1). Whereas the
intrinsic muscles were lacking in the syrinx, there were
two extrinsic muscles. The sternotracheal (ST) muscle,
one of the extrinsic muscles of the syrinx, was located
(average 14.82 ±.0.36 mm) above pessulus. The
tracheolateral (TL) muscle, another extrinsic muscle was
located at the side of the trachea laterally of the ST
muscle to MTL and it was inserted on MTL (Fig. 2).
In histological sections, taken from the level of
the third and fourth CTS, the lamina epithelialis of the
mucosa was lined with non-cornified stratified
squamous epithelium. There were cilia on the apical
surfaces of the epithelial cells. The lamina propria and
the submucosa which were placed under the epithelium
were composed of compact elastic fibres and loose
connective tissue, respectively. The most peripheral
portion of the propria-submucosa of lamina epithelialis
contained small numbers of mucous glands. Pincus acid
orcein-Giemsa stain revealed that the submucosa
displayed dark-brown stained elastic fibers. Deep to this
loose connective tissue was a prominent stratum of
longitudinally oriented elastic fibers between the hyaline
cartilages of the syrinx. A longitudinal muscular layer
was found throughout the section. The outermost layer
of the section, tunica adventitia, consisted of loose
connective tissue. In the trachea, the lamina epithelialis
of the mucosa was lined with pseudostratified,
columnar, ciliated epithelium with goblet cells. The
lamina propria and the submucosa, which contained
loose connective tissue and mucous glands, were found
below the epithelium. Throughout the section, a thin
longitudinal muscle layer was observed in the trachea
The morphological structure of the syrinx has
been described in many bird species (4, 8, 9, 11, 15, 22,
24). This study presents some characteristics of this
organ in pigeon. Since both the trachea and bronchus
primarius participated in its formation, the syrinx in the
pigeon could be classified as of tracheobronchial type
comparable to that of chickens (13, 15, 19). This type of
syrinx is the most common type in birds (13). The
topographical findings of the syrinx in the pigeon were
comparable to those of the chicken (6, 7, 15, 19), new
world pigeon (4)
and ostrich (25).
The tympanum was composed of 5 tracheal
cartilage rings different from those described in the
chicken (2, 6, 7, 15, 18, 19), new world pigeon (4),
singing birds (21), and duck (22). The CTS are
composed of four C-shaped cartilage rings as in
chickens (6, 7, 15, 19) and in ostrich
(25). Although the
CTS was described for several species as joined part of
(15), we found out that in Bursa Roller
Pigeons CTS appeared as a separate cartilage groups.
The CBS were composed of 5 C-shaped half-rings as
described for new world pigeons (4) but different from
those in other birds (15, 18, 19, 22, 24, 25).
The pessulus in pigeons was composed of
connective tissue as described in new world pigeons (4)
and ostrich (25). This structure is cartilaginous in
chickens (6, 15, 18, 19) and ossified in singing birds (11,
24). The connective tissue structure of the pessulus in
pigeons is probably due to the fact that the pigeon is not
a singing bird and thus neither osseous nor cartilaginous
structure is needed to keep the pessulus tight.
Vibrating membranes are present in the walls of
the bronchi. The MTL in pigeons was in the same
location as described for the MTL of new world pigeons
(4) and pigeons (8, 18) and a different location was
found out in the chicken (2, 7, 15, 19), gull (15), singing
birds (24) and ostrich (25). This membrane is defined as
the sound organ in many avian species (15) and the TL
muscle inserts to this membrane so it can produce
significant sound. The MTM covers the open ends of the
CBS as reported in some other species (2, 4, 6, 8, 9, 10,
11, 15, 19, 23).
The syringeal muscles are paired, lie to the
right and left sides of and are divided into two groups,
extrinsic and intrinsic. Extrinsic muscles are the ST and
TL in domestic fowl. Intrinsic muscles are found in
singing birds, suboscine passeriformes, and parrots (2,
16, 21, 23). The TL muscle is found only in the pigeon
(18). In this study, extrinsic muscles, TL and ST, were
observed in pigeon syrinx. The TL muscle was
connected to the MTL, so it might vibrate against MTL
and thus produce the sound. A second muscle, ST,
draws the cartilages to each other and so MTL is kept
The histological structure of the syrinx has been
investigated in only few bird species. Of those, the
histological structure of the syrinx in the pigeon was
similar to that of the chicken (12), duck (22), and ostrich
(25). The mucosa lining, in particular, was the same as
that of the chicken and duck (3, 5, 12, 22).
This study presents some of the characteristics
of the sound organ in pigeons. Although the
topographical and histological characteristics of the
syrinx showed close resemblance to that of other bird
species, some differences were observed regarding its
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