الفهرس 
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Abstract
This investigation was carried out on 105 male and female of
apparently healthy pigeon. Their ages ranged from 1 day to 6 months.
Specimens of each organ were taken immediately after sacrifice and
processed till 5 - 6 micrometer thick sections were prepared and
stained with H & E, Va Gieson’s Stain, Crossman’s trichrom Stain,
Weigert’s Elastic Stain, Silver impregnation and toluidine blue for
must cells. Also, some were staiend for glycogen PAS
For histochemical rections, SDH, non-specific esterase, alkaline
phosphatase acid phosphatase and ATPase were studied.
The results revealed that OESOPHAGUS
Was narrow, muscular highly distensible tube extending from
the posterior end of the pharynx to the glandular stomach but inerr
upted before its end by the crop. The mucosa of the oesophagus was
thrown into numerous longitudinal folds. The pigeon oesophgeal epith
elium at ages 1 day, 1,2 week and 1 - 2month ~‘as stratified squa
mous non keratinized while at 4-month age, slight keratinization
began to appear, at 6 months, the keratin layer increased in thickness
tan in the previous age.
The lamina propria, at young age was made up of collagen
fibers with little elastic and delicate reticular fibers with advance
of age, the lamina propria increased in thickness and amount of
fibers also increased. With the lamina propria were found many blood
vessels, nerves and lymphatic also numerous mucous glands. The
latter began as wide acini at youg age, then became simple branched
acinar and finally became well developed compound acinar and num
erous at mature age. The glands were merocrine in their mode of
secretion. They opened into the lumen via ducts passing through the
lining epithelium of the mucosa.
The lamina muscularis mucosae consisted of longitudinally
arranged smooth muscle bundles dipped in the cores of the mucosal
folds and its thickness increased with the advancement of age.
The submucosa consisted of indistinct layer of loose conne
ctive tissue cells.
The tunica muscularis consisted of thick inner circular and
them outer longitudinal layers of smooth muscle fibers, and the 2
layers were separated by connective tissue band contain nerve plexus
also the thickness of tunica muscularis increased with the .progress of
age. Externally, serosa or adventitia were marked.
CROP:
The structure of crop was identical to those of oesphagus
while the follwoing differences were recorded, the lack of mucous
glands throughout the greater part of the organ except at the junction
of crop with the oesophagus. The mucosa was highly folded and the
fold were high, broad and compound. The lamina muscularis were
thin. At the breeding season, the lamina epithelialis of the dorsal
wall was highly proliferating and its thickness increased several
times more than in non-breding season, while ventral wall showed no
change.
PROVENTRJQJ LU S
The proventriculus of pigeon was spindle in shape and showed
several macroscopic papillae. The mucosa was thrown into plicae
(folds) and sulci. The plicae and sulci were covered and lined with
simple columnar epithelium. The plicae at one day were short at
one week folds were more developed cylendrical in shape, with the
progress of age, the folds became well developed. The lamina propria
was made up of dense collagenic, few elastic and reticular fibers,
with numerous blood vessels. At young age it free from glands while
at 6-months simple and branched glands were present. The proven
tricular glands formed the greater part of the thickness of the proventricular
wall. At one day, they were rounded lobule, with the
advancement of age, they increased in size and became more devel
oped and their shape varied from hexagonal, pentagonal to poly
morphic entities. The preoventricular gland were found in the propria
interior to the muscularis mucosa. The lamina muscularis mucosae at
one day, was rarely seen. At one week it appeared as very thin
layer of longitudinally arranged smooth muscle fibers outer to the
proventricular glands, and with advance of age it increased in thick
ness up to 6-month, became well-developed and consisted of 2 layers.
(outer & inner). The submucosa was very thin. The tunica muscularis
externa consisted of inner thick circular and thin outer longitudinal
layers of smooth muscle fibers and its thickness increased with the
advancement of age. The serosa was of loose connective tissue and
contained blood vessels, and Auerbach’s plexuses.
GIZZARD
It was lattened from side to side and rounded, some what
like-biconvex lens, each surface was covered by a glistening tendinous
layer thicker at the cnetre of the surface and thinner away towards
the margins. The interior of the gizzard was provided with green
thick horny layer. This colour results due to regurgtor of bile from
duodenum. The inner most layer of the gizzard was the keratin layer
which at one day, appeared to be serrated with ill eveloped striation
The keratin layer increased in thickness with the advancement of
age and became more thicker than the glandular layer. The mucosal
surface was indented by numerous gizzard pits. The surface epithelium
and pits were covered by columnar epithelium. The gizzard pits were
longer and reached up to the 2/3 thickness of lamina propria, where
the remainder 1/3 thickness was included by the branched tubular
glands which at 6-months decreased in size than in young age, and
the glands were more convoluted and the distal portions were wider.
The lamina propria was made up of fibrous connective tissue and its
was obscured by tubular glands. The lamina mucularis mucosa was
absent. The submucosa, at young age was thin layer and its thickness
increased with the progress of age. The tunica muscularis externa,
at one day, consisted of 3 distinct layers inner oblique, middle cir
cular and outer longitudinal layers of smooth muscle fibers espeically
at the circumference of the gizzard, at 2 weeks, thick inner oblique
(diffuse fibers) thick middle circular and very thin outer longitudinal
at one month till 6 months. The inner oblique muscles became very
thin, far away from the circumference of the gizzard the tunica
muscularis consisted only of two layers ( inner circular and outer
longitundinal ) in the form of regular bundles . At 6-months the
tunica muscularis formed of a main bulky inner circular and very
- thin outer longitudinal layers. At the area of junction between the
tendinous and muscular part, all the layers of the gizzard were thin
and the gizzard tubular glands were the shortest with no branching,
however, the serosa appeared to be the thickest at the tendious part
and contained many blood vessels and adipose tissue.
Glycogen
There was glycogen deposition in the columnar cells of the
mucosal folds of the proventriculus and in the central collecting
duct epithelium of proventricular glands. The glandular epithelial cells
were devoid of glycogen.
Alkaline Phosphatase:
The oesophagus showed a strong reaction for alkaline phos
phatase in the basal cell layer of lamina epithelialis and negative in
the rest of layers and moderate reaction in the basal region of the
glandular epithelium. In the proventriculus the mucosal folds showed
a weak reaction but an intense one was in the proventricular glandular
epithelial cells especially in the basal parts of the cells. The keratin
layer of the gizzard reacted moderately for alkaline phosphatase
while weak reaction was in the glandular layer and weaker in the
muscular layer. Acid phospharase
The lamina epithelialis of the oesophagus had a negative
reaction for acid phosphatase and moderate one in the oesophageal
glands. In the proventriculus, there was intense reaction for acid
phosphatase in the fold epithelium and strong reaction in the secondary
duct epithelium of the proventicular glands. The glandular layer of
the gizzard showed strong reaction and weaker one in the muscular
layer.
ATPase:
The lamina epithelialis of the oesphagus presented a negative
reaction, while moderate one in the oesophagcal glands, and in the
crop there was weak reaction for ATPase and moderate reaction in
the muscular layer. The mucosal fold epithelium of the proventriculus
showed moderat reaction, as also in the glandular epithelial cells. In
the gizzard the activity of ATPase was strong in the glandular units
and intense in the muscular layer.
Non-Specific esterase
The oesophagus showed weak reaction in the lamina epithe
lialis, but moderate in the oesophageal glands while strong reaction
in the muscularis mucosae. In the crop the reaction was negative in
the epithelium but intense one in the muscularis mucosa and muscularis
externa. There was strong reaction in the mucosal fold epithelium
and in the proventricular glandular cells whille intense reaction in
the central collecting ducts of glandular lobules. The keratin layer
of the gizzard showed weak reaction, the glandular layer had a mode
rate reaction, while strong one in the submucosa specially in the
muscle bundles of inner circular layer of muscularis externa. The reac
tion had increased by advance of age.
SDH;
In the oesophagus, there was weak reaction in the lamina
epithelialis and moderate one in the oesphageal glands. The lamina
epithelialis of the crop showed moderate reaction. The other layers
were negative. In the proventriculus the mucosal fold epithelium
showed moderate reaction and strong one in the proventricular gland
ular epithelia. The glands of the gizzard showed moderate reaction,
while the other layers were negative. The reaction was increased by
advance of age.