2. Introduction
The pituitory gland or hypophysis is structurally
and functionally most complex endocrine gland.
Located in th ebrain attached by slender
hypophysial or infundibular stalk,just behind the
optic chiasma.
The pituitory gland has double origin as it is partly
derived from oral ectoderm and partly from the
brain.
The pituitory gland has two main parts:
I. Adenohypophysis
II. Neurohypophysis
3.
4. Adenohypophysis
I. It is also called
glandular lobe.
II. This is anterior two
third of the gland
which is formed
from stomodeal
portion.
III. It has following
parts
Pars distalis, Pars
tuberalis, Pars
intermedia
Neurohypophysis
I. This is formed from
neural ectoderm.
II. It has following parts:
Pars
nervosa,Infundibulum.
5. Chromophils
These are ovoid cells with granular cytoplasm
nuclei.They take up acid or basic stains and are
classified into two types
a. Acidophils ( alpha cells):-
Acidophils are rounded or ovoid cells 10 to 20
micron have cytoplasm that stains red or orange
b. Acidophils are of two types
• Somatotrophs:- These cells secrete
somatotropin hormones and growth
hormaones
• Mammotrophs( leutotrophs or prolactin cells):-
These cells secrete prolactin hormone.
6. Adinohypophysis
Pars distalis:-Pars distalis or anterior lobe is the
largest(75%)part of pituitory gland supported by
collagenous capsule.
In this region ,two major types of cells occur
namely chromophils & chromophobes .
7. Basophils( beta cells):-
They are irregular shaped and stain with basic
dyes.
Basophils are of two types
i. Thyrotrophs :- These cells secrete thyrotrophic
hormone
ii. Gonadotrophs :- These cells secrete
gonadotrophic hormone .i.e. FSH ( Follicle
stimulating hormone ) and LH ( leutinizing
Hormone)
8. Chromophobes (chief cells)
These cells are spherical ,elongated and irregular
cells and appear in groups near center of cords
These cells contain light staining cytoplasm.
These cells produce adrenocorticotropic
hormone(ACTH)
9. Pars tuberalis
Pars tuberalis is a layer of cuboidal cells that
covers the part of stalk and tuberal area of the
brain.
It is highly vascular.
Not known whether these cells produce any
hormon or not.
10. Pars Intermedia
It is a narrow region between pars distalis and
pras nervosa.
It contains a stratum of epithelial cells which is
formed by several layers of polygonal cells and
they are basophilic.
The pars intermedia secrete melanonocytye
stimulating hormone in lower vertebrates like fish
and amphibians ,but in the mammals the function
of MSH is obscure.
12. Neurohypophysis
It is formed by ventral cylindrical outgrowth from
the floor of the diencephalon,which forms the
stalk and posterior 1/3 of the pituitory gland.
The posterior 1/3 of the gland ,whioch is formed
by swollen end of ventral outgrwoth, is called pars
nervosa or infundibular process.
The cells of neural lobe are called pituicytes.
Two hormones Oxytoxin and Anti-diuretic are
secreted from neurohypophysis.
