Download Benha University Histology Exam for 2nd year Faculty of Veterinary

Benha University
Faculty of Veterinary Medicine
Histology and Cytology Department
Histology Exam for 2nd year
2nd Semester
June 2011
Time: 3 hours
Poultry and Fish Exam
Students transferring from other colleges
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(I) Give full histological structure of the following:-
Tongue of birds.
Lamina Epithelialis: - It is also lined with thick stratified squamous epithelium which is
cornified on the ventral surface and the anterior tip. Transverse large papillae directed
posteriorly with found.
Lamina propria submucosa:- It is formed from dense connective tissue and ungual salivary
glands were found
The main mass of the tongue consists of striated muscle and a small bar of cartilage or
bone.
There are no teeth in domestic poultry.
In selecting its food, the chicken utilizes taste, vision and tactile sense. The sense of smell
is considered to be poorly developed in the chicken. The sense of taste is different from
that in man and is more acute when additives are in water rather than in feed. The chicken
can discern shape, size and colour and can feel material with its tongue and mouth. Taste,
colour, size, shape and consistency can, therefore, be important to feed consumption.
Chickens do have food preferences which in part can be learned. This latter is important
when feed is changed. Appetite is influenced by contractions of an empty crop, an empty
rectum and cold and visual stimuli such as the sight of food. Factors influencing the
amount of food consumed are position in the social order, social stimulation, availability
of food and form of the food. Chickens have no teeth or soft palate and there is no
mastication as occurs in mammals. The beak is used in grasping the food which is then
propelled backward to the esophagus where it is carried by peristalsis, aided by gravity,
down to the crop.
Fungiform (8--16 in number), filiform (5--16 in number), circumvallate and foliate
(numerous) were recorded profusely innervated in the various regions of the tongue.
Neuro-muscular spindles related either with the non-myelinated, myelinated nerve fibres
or with the ganglia via pre- or postganglionic nerve fiber showed cholinesterase (AChE)
positive activity in the form of dark brown patches. Neural network over the glands,
formed the basket envelope likestructures. Glands showed positive cholinesterase (AChE)
reaction on the periphery. Dot-like nerve endings were connected with the neural terminal
network in the foliate papillae region and motor end plate like endings on blood vessel,
were occasionally recorded. Parasympathetic ganglia of various shape and sizes, arranged
in chain-like fashion were observed in the connective tissue space between the fungiform
and circumvallate papillae and foliate papillae region. The pre- and postganglionic fibers
of these ganglia were related with the anteriorly and posteriorly located papillae via the
neural terminal network.
Duodenum of chicken.
The small intestine is similar to that of mammals but is more uniform throughout its
length. Diffuse lymphatic tissue is present in the lamina propria and the submucosa, and a
third layer of circular smooth muscle may be present in the muscularis externa.
The villi were quite tall and finger-like; very closely packed.
The tips of the villi were rounded
The surface area devoted to goblet cells was considerably less than that of the columnar
epithelium.
The lining epithelium was simple columnar cells with goblet and endocrine cells scattered
throughout. The columnar epithelium had large, oval, vesicular, basally located nuclei. A
striated border was present. The mucus goblet cells were scattered among the columnar
celljs. These cells had oval vesicular nuclei in the basal region, which were smaller than
the nuclei of the columnar cells
The lamina propria was thin and filled the cores of the villi. Some blood capillaries,
smooth muscle cells and areas of lymphocytic infiltration were observed
The muscularis mucosa formed a longitudinal layer of smooth muscle fibers, with some
fibers extended into the lamina propria.
The tunica submucosa was thin and formed from collagen and reticular fibers.
The muscular layer was composed of inner circular and outer longitudinal smooth muscle
cells.
The villi of the jejunum were tongue-shaped to cylindrical, their length the same or
slightly less than that of the duodenal villi. The tips of the villi were flattened
The lining epithelium was simple columnar with a prominent striated border. The goblet
cells were more numerous than in the duodenum
The lamina propria was highly cellular and filled the cores of the villi Lymphocytic
infiltrations were present, which the lymphocytes were characterized by electron dense
particles and more cytoplasm. There were reticular and elastic fibers in the lamina propria,
supporting the simple tubular intestinal crypts of Lieberkuhn. These glands decreased in
number toward the end of the small intestine.
The
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Bursa of fabricius
The cloacal bursa is an oval sacculated organ dorsal to the cloaca and communicating with
it by a small opening.
It is a central lymphoid organ that seeds B lymphocytes to the germinal centers of
peripheral lymphoid deposits and the spleen, and is the primary site for the synthesis of
immunoglobulin in the young bird before involution commences from 3-4 months.
The mucosal wall is thrown into folds covered by a pseudostratified columnar epithelium
continuous with that of the cloaca.
The folds are subdivided by connective tissue trabeculae into lobules.
Each fold consists of a densely populated outer cortex of lymphocytes and an inner
sparsely populated medulla separated by a layer of undifferentiated epithelial cells.
Lymphoid tissue and the overlying mucous membrane are in close apposition and
lymphocytes migrate through the epithelium.
The mucosal associated lymphatic tissue is present in the tubular digestive tract.
The densest aggregation is found in the narrow proximal region of the caecum, the socalled poly cryptic caecal tonsil.
Both T and B lymphocytes are present.
(II) In table, Compare between the histological structure from the following:-
1- ESOPHAGUS
Tunica mucosa of the esophagus was thrown into numerous longitudinal folds,
variable in length
The mucosal epithelium was a thick stratified squamous type non keratinized or
incompletely kertinizied. The
lining epithelium rested on a well-developed basement membrane.
The lamina propria was composed of connective tissue and rich in blood vessels, many
collagen fibers and reticular fibers. It was, however, characterized by lack of elastic fibers
and lymphoid tissue. Large simple branched alveolar mucus glands were present. A tall
columnar epithelium, whose cells contained flattened or oval basally situated nuclei, lined
the mucus glands. This lining decreased to a cuboidal shape as it approached the surface.
The esophageal glands were mucus in nature,
Crop
The crop has a resident bacterial population, mostly Lactobacillus species, which ferment
some carbohydrates in the food for their own purposes. Lactic acid is the by-product of
this fermentation so the pH of the feed drops as the food is retained in the crop.
Geese and ducks do not have a true crop but have an enlarged part of the lower esophagus.
This gives waterfowl a similar ability to store food but bacterial fermentation is less
compared to other poultry
It is non-glandular caudal diverticulum situated two-thirds of the way down the esophagus.
In the pigeon two lateral glomerular sacs secrete crop milk.
The thickness of crop lining epithelium increased and was thicker than of the esophagus
and had some keratinization.
The lamina propria had some collagen fibers .At the esophageal-crop junction; the crop
had no mucus glands. The esophageal glands at the junction ended abruptly but all other
layers were continuous through the crop.
2- Stomach
The stomach consists of the glandular proventriculus and a muscular ventriculus.
Proventriculus once the food reaches the end of the esophagus it enters the proventriculus.
The proventriculus is distinguished by its thick glandular mucous membrane. The glands
secrete hydrochloric acid and pepsinogen (the precursor of pepsin). The acidity of the food
is reduced to a pH that enables pepsin to be formed and to catalyse protein hydrolysis.
Lamina Epithelialis:The gastric epithelium of the proventriculus is simple columnar and mucus secreting.
Lamina propria:A thin lamina propria separates it from the lobules of the submucosal glands and consists
of thin loose connective tissue.
These glands form an almost continuous mass of tissue, and penetrate the tunica mucosa
also, with adjacent lobules separated by fine strands of connective tissue. Each gland
lobule contains a central cavity with straight secretory tubules radiating to the interlobular
connective tissue. An excretory duct drains onto the gastric mucosal surface.
The glands contain only one type of cell which secretes acid and pepsinogen, thus
combining the functions of both the chief and parietal cells of the mammal.
Lamina muscularis mucosae;It is thin layer and patches of smooth muscle fibers and the glands penetrate it
Tunica Submucosa
It is loose connective tissue
Tunica muscularis is arranged as inner circular and outer ongitudinal layers of smooth
muscle. Tunica serosa:
It is thin layer of loose connective tissue covered by flattened mesothelium.
Ventriculus (or) Gizzard (or) muscular stomach.
The gizzard is a flattened sphere surrounded by powerful muscles that generate high
pressures within. Muscular contractions can physically break up very dense food particles
such as whole cereal grains. Particles of grit are retained in the gizzard and they provide an
abrasive surface that helps in grinding the food. The submucosa of the gizzard secretes a
protein— polysaccharide substance called koilin. The koilin solidifies into short rods when
it reaches the acid conditions in the gizzard and the rods cross-link to form a mesh around
the gizzard wall. This protects the wall from damage and provides an abrasive surface for
the grinding process.
The luminal surface is lined with secretory product of the mucosal glands, which solidifies
at the surface to form a hard cuticle of koilin.
Lamina Epith.
It is formed from one layer of simple columnar epithelium secretory types
Lamina propria:
It consists of layer of loose connective tissue containing branched and unbranched tubular
glands which lined by cuboidal to low columnar cells ( chief cells and basal cells)
also have low amount of endocrine cells but not open into the luminal of the gland but face
to the blood capillary. Lamina muscularis mucosa:
IT IS ABSENT IN GIZZARD. Tunica submucosa:
It is loose connective tissue fused with lamina propria. Tunica muscularis mucosae:
It formed the main bulk of the gizzard. It is smooth muscle form three layer in different
direction which ranged from oblique to circular and longitudinal, these entire layer were
connected by collagen fiber in between. Tunica serosa
• It is subserosal layer which is fibrous connective tissue and covered by mesothelium. The
gizzard covered externally by tendinous layer.
3- Swim Bladder
The swim bladder is classified as digestive organ in some species, where it classified as
respiratory organ in other species.
The histology of the swim bladder is extremely variable between species but, nevertheless,
very important clinically. In some fishes, the swim bladder has essentially the same
histology as its origin, the digestive tract. In other fishes, the anatomy of the swim bladder
is greatly reduced. There may be no more than an inner mucous membrane layer with a
thin outer connective tissue covering.
In sturgeon, pepsin-secreting and mucus-secreting glands are still found in the swim
bladder, which has all of the components of a digestive viscus. Most species have swim
bladders covered with a simple squamous epithelium over a layer of dense fibrous
connective tissue with longitudinal, circular, and oblique fibers arranged in layers.
Guanine crystals, shaped like thin platelets embedded in this connective tissue, give the
swim bladder of some species a distinctive silver color. The outer layers of connective
tissue are joined to the inner layers of the structure by a loose, elastic, connective tissue
layer. The inner epithelium of the swim bladder is commonly cuboidal and may be
ciliated, partially ciliated, or completely devoid of cilia. The epithelial layer can include
pigment cells. It is supported by a muscularis of smooth muscle in most fishes.
Rainbow trout have a thin muscularis of smooth muscle with many elastic fibers arranged
with the outer layer of fibers running longitudinally and inner fibers circumferentially.
Perch have a thin-walled swim bladder covered with a peritoneum containing numerous
melanocytes. Underneath is a fibrous tunic that covers an inner layer of circular connective
tissue fibers. The only evidence of a muscularis is in the region of the oval or gas gland.
Some groups of the catfish and loach families have their swim bladder protected within a
bony capsule derived from the vertebrae.
The gas gland (oval, red gland, red body) varies widely in shape and form. It is often oval
or round but can be a torus or stellate or dendriform. It can occupy a small or large
percentage of the swim bladder wall. The gas gland is a highly vascular organ that usually
consists of parallel venous and arterial rete mirabile arranged in a counter-current fashion.
There are many versions of these glands in different species. In the codfish and the
stickleback, only a single pair of retia is formed between the venules and arterioles of the
gland. As many as three sets of retia can occur in other species, with retia forming at the
capillary, venule/arteriole, and vein/ artery levels.
It consists of:Simple sq. epith (s.cuboidal or columnar and pigmented)
Dense fibrous CT
Three directions of smooth muscles
Guanine crystals (thin elements present in the CT giving the fish its silver appearance).
Esophagus
Epithelium→ st.sq.epith. it may be ciliated columnar or cuboidal in some spp.
L.Propria→ loose CT
T. Submucosa→ fibroelastic CT
T.Muscularis→ outer circular and inner longitudinal and oblique skeletal muscles then this
muscle orientation change caudally and become smooth muscles
T. Serosa→ loose CT lined by mesothelial cells.