V. S. of TOOTH of Mammal
1. Teeth are present in
bucal cavity.
2. Tooth is distinguished in to crown, neck and
root.
3. Crown is the exposed part of the tooth which
projects out of the jaws in the oral
cavity and is white
glistening in appearance.
4. Neck is the middle part of the tooth which is
above the root surrounded by the gum.
5. Root is present in
the bony socket of jaw bone or alveolus.
6. The vertical section
o tooth shows following histological parts.
A) Pulp cavity B)
Dentine C) Cement D) Enamel
Cavity enclosed by
tooth is called pulp cavity. Pulp cavity is surrounded by relatively soft
dentine. Tooth is fitted into the socket
of jaw by cement substance. Enamel is hardest part of tooth, covering dentine
from all side.
Function of
tooth: Mastication of Food
SALIVARY GLAND
1. Salivary
glands are also called as parotid glands.
2. It
is a tubular or alveolar gland.
3. secretes
saliva contains digestive enzyme ptyalin.
4. Each
salivary gland consists of large number of lobules bound together by connective
tissue, blood vessels, nerves and numerous fat cells.
5. Each
lobule consists of alveoli or acini, lined by mucus cells and serous cells.
6. From
alveoli arises duct unites to form a salivary duct which opens
into the mouth.
7. Histologically
salivary gland shows three types of cells which are as follows.
a) Serous cells secrete ptyalin.
b) Mucous cells secrete mucous and
c) Crescent cells - replace worn out cells.
Function of Salivary gland:
1. Saliva helps in moistening of food particle.
2. Salivary amylase act upon carbohydrates.
T. S. of Stomach of Mammal
Stomach is bag like structure.
1. Histologically the stomach shows following
parts
2. Serosa
3. muscularis
externa
4. Sub-mucosa
5. Muscularis
mucosa
6. Mucosa
a. Outer
most layer of stomach is called serosa is made up of squamous epithelium.
b. Muscularis
externa consists of outer longitudinal and inner circular muscle layer.
c. Below the muscularis there is a sub mucosa
made up of connective tissue containing blood vessels, nerves and lymph
vessels.
d. Below the sub mucosa there is muscularis mucosae consists of two layers of
muscle . according to their plan they are called longitudinal muscle layer and circular muscle layer
e. The
muscularis mucosae is followed by a thickest layer called mucosa consists of simple columnar epithelium and gastric glands.
f. The
gastric glands are long and arranged parallel to each other. These are simple or simple tubular gland.
g. The
gastric glands consists of two types of
cells namely oxyntic and peptic cells.
h. The
peptic cells secrete digestive enzymes and oxyntic cells secrete HCl.
Function of stomach:
1. Digestion of food.
2. Secretion of gastric juice.
3. Gastric juice contains HCl and Pepsin.
Histology
of Intestine
The intestine is long
tube like divisible into Small intestine and large intestine. The small
intestine consists of Duodenum and Ilium, while large intestine consist of
Colon and Rectum.
T.
S. of Ilium of Mammal
Histologically, the
ileum has the same basic structure as the jejunum:
1. Serosa
2. muscularis
externa
3. Sub-mucosa
4. Muscularis
mucosa
5. Mucosa
1. Outer
most layer of stomach is called serosa is made up of squamous epithelium.
2. Muscularis
externa consists of outer longitudinal and inner circular muscle layer.
3. The
submucosa contains is made up of connective tissue containing blood vessels,
nerves, lymph nodes and the Meissner’s
plexus.
4. Below the sub mucosa there is muscularis mucosae consists of two layers of
muscle . Accordingly, they are called
longitudinal muscle layer and
circular muscle layer.
5. The
muscularis mucosae is followed by a thickest layer called mucosa
6. The
mucosa membrane of ilium shows large and small finger like folds called villi
covered by simple columnar epithelium with dispersed goblet cells.
7. Each
villus shows presence of blood vessels, lymph vessels and lacteal.
8. At
the base between the villi Crypts of Liberkuhn are present which lead into Bruner's gland.
4. The secretion of
these glands forms digestive juices.
The secretions of these glands form digestive
juices.
T. S. of Liver of Mammal
Liver is the largest
digestive gland. Histologically it shows following parts.
1. The liver is
composed of polygonal lobules containing a central vein in the centre and the
portal canal at the corners.
2 Each portal canal
consists of connective tissue strand and contains a
branch of portal vein,
hepatic artery, bile duct and lymph vessel.
3. The liver cells are
polyhedral or rectangular and arranged in single celled
long chains extending
radially from the central vein to the periphery of the
lobule.
4. Each liver cell has
granular cytoplasm and a prominent nucleus.
Function of liver
Liver has several
functions.
Liver produces bile
which plays important role in the digestion of food.
7. It stores the
soluble products of digestion and metabolizes them for
assimilation.
9. In
liver toxic substances are detoxicated in the liver.
10.
It
helps in emulsification of fat.
T.
S. of Pancreas
Pancreas
is exocrine as well as endocrine in function.
1. The pancreas
consists of two portions namely endocrine and exocrine portion.
2. The exocrine portion
consists of a series of lobules or acini; bound together by connective tissue
containing blood vessels, nerve endings and lymph vessels.
3. Each lobule or
acinus is made up of pyramidal pancreatic cells having
granular cytoplasm and
prominent nuclei.
4. The lobules or acini
open into small ductules which join to form large ducts and which finally form
the main pancreatic duct.
6. The endocrine
portion consists of Islets of Langerhans between the acini.
Functions of pancreas
1.The exocrine portion of pancreas
produces pancreatic juice which contains trypsin, amylase and lipase enzymes.
2. Endocrine part produces two hormones.
a. Insulin produced by beta
cells.
b. Glucagon produced by
alpha cells.
T. S. of Kidney of Mammal
Kidney is main part of excretory
system which help in removal of nitrogenous waste.
1. Each kidney is bean shaped.
The kidney is
surrounded by a capsule of dense connective tissue.
2. Kidney is composed
of outer cortex and inner medulla.
3 The cortex contains
numerous uriniferous tubules having Bowman's capsules and glomeruli
4 The medulla is
consists of some renal pyramids consisting of modularly rays, columns of
Bertini, tubules of medulla and connective tissue.
Function of Kidney
a. Removal
of nitrogenous wastes from body.
b. Maintenance
of water balance inside of body (Osmoregulation)
T. S. Of Testis of Mammal
Testis are the male
gonads.
1. The testis is
somewhat oval or rounded in shape surrounded peritoneum
followed by a layer of
fibrous connective tissue, the tunica albuginea.
2. Histologically
each testis shows presences of convoluted seminiferous tubules separated from
one another by inter tubular connective tissue.
3. In
connective tissue blood vessels and interstitial cells (Leydig cells) are present.
4. The
interstitial cells secrete a hormone testosterone
5. Each
seminiferous tubule is oval or rounded in appearance and surrounded by basement membrane and lined by
germinal epithelium
6. Seminiferous
tubule shows presence varous stages of developing sperms includes, spermatogonia, primary spermatocytes,
secondsry spermatocytes and spermatids.
7. In
between the germinal cells certain large sertoli cells are present
Function of Testis
a.
Seminiferous tubule produces sperm.
b.
Interstitial cells secret male sex hormone
called testostron which control male secondary sex character
c.
Sertoli cells of seminiferous tubule supplying
nourishment to the developing sperms.
T. S. of Ovary of Mammal
Ovary is female gonad.
1. The ovary is lined
by germinal epithelium which is bounded by the connective tissue, the tunica
albuginea.
2. The mass of the
ovary is called stroma formed of connective tissue rich in
elastic fibers with
large blood vessels lymphatic's and nerves.
3. In the stroma are
egg cells in the various stages of development, each
surrounded by a
nourishing epithelial layer, the follicle and blood vessels.
4. Ovary in the stroma shows, presence of various stages
of developing ova. It includes, primary
follicle (ovum and single layer of
follicle cells), secondary
follicle (double layered follicle), mature follicle with antrum, ruptured follicle,
fully formed corpus luteum and corpus albicans.
5. The primary
follicles develop from primordial follicles present in the germinal epithelium.
6 The follicle and ovum
slowly move deeper in to the stroma and become
larger.
Mature follicles shows
presence of follicular cavity filled with follicular fluid called oestrogne.
7. Later ovum and cells
around it become separated by fluid filled space from the rest of the follicle
except at one point forming antrum.
8. The enlargement of
the ovum and follicle results in the formation of a mature follicle or graffian
follicle.
Function of ovary
a. Production
of ova.
b. Developing
follicle produces oestrogen hormone which control female secondary sex
characters.
T. S. of Uterus
Uterus is hollow pear
shaped thick walled structure present between vagina and fallopian tube.
It consists of fundus,
corpus and cervix.
2. Histologically the
wall of the uterus shows three layers
1) Primetrium or Serosa
2) Myometrium or muscularis
3) Endometrium or
mucosa.
1. Primetrium or
serosa: it is the outer most protective coat forming the
broad ligament through which blood vessels, lymphatics and nerves reach the
uterus
2. Myometrium or
muscularis: this is the middle muscular coat of
uterus. it is very thick layer consists of smooth muscle fibers, connective
tissue and large blood vessels.
it consists of three sets of muscle layers and accordingly they are
called as outer longitudinal muscle, middle oblique muscle and inner circular
muscles.
Oxytocin hormone secreted by pituitary gland control the movement of
these muscles.
3. Endometrium or
mucosa: it is the inner most layer of uterus occupies
major portion of lumen of uterus. The endometrium consists of two membrane.
a. Inner Endometrium functionalis
b. Outer Endometrium
basalis.
a.
The endometrium functionalsi is lined by mucosal epithelium linded by simple columnar
ciliated epithelium and underlying submucosa. Endometrium functionalis undergoes
cyclic changes during menstruation.
The stroma of uterine
wall consists of simple tubular uterine glands.
b.
Endometrium basalis: this is the region of uterus remain unchanged during
disrutvie phase of sex cycle or menstrual cycle.
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