The pituitary gland, also known as the hypophysis cerebri or master gland, regulates many other endocrine glands. It consists of an anterior and posterior lobe with distinct developmental origins, structures, and functions. The anterior lobe secretes trophic hormones that control other endocrine glands, while the posterior lobe stores and releases oxytocin and antidiuretic hormone. Pituitary tumors are usually benign adenomas but can cause hormone excess or deficiency by compressing or destroying normal glandular tissue. Craniopharyngiomas are also benign tumors near the pituitary that may affect hormone function and vision.

1. DR.SRUTHY.K
DEPARTMENT OF ORAL PATHOLOGY
AND MICROBIOLOGY

3.  The hypophysis cerebri or pituitary gland is an
ovoid neuroglandular body suspended from the
floor of the third ventricle by a stalk known as the
infundibulum. It regulates the secretory activity of
many other endocrine glands and tissues; hence the
pituitary is sometimes called “the master gland”.

4. (A)ADENOHYPOPHYSIS CEREBRI:
 1- Pars Distalis (pars anterior)
 2- Pars Tuberalis
 3- Pars Intermedia
(B) NEUROHYPOPHYSIS CEREBRI:
 1- Median eminence
 2- Infundibulum: Neural (Infundibular) Stalk
 3- Pars Nervosa

5. Measurements:
 Breadth (Transverse) — 12 mm.
 Length (Antero-posterior) — 8 mm.
 Weight — 500 mg.
Situation:
 The gland is lodged in the hypophyseal fossa of sella turcica
of the body of sphenoid bone. The fossa is roofed by the
diaphragma sellae, which is a fold derived from the
meningeal layer of Dura mater and extends from the
tuberculum sellae and middle clinoid processes in front to
the upper margin of the dorsum sellae and posterior clinoid
precesses behind.
 The diaphragma sellae is pierced in the middle by the
infundibulum (pituitary stalk), and is continuous on each
side with the roof of the cavernous sinus.
 The capsule of the gland is adherent to the meninges of the
fossa; hence the gland is not surrounded by a film of cerbro-
spinal fluid.

6. The gland consists of an anterior lobe or adeno-hypophysis
and a posterior lobe or neuro-hypophysis. In development,
structure and functions these two parts are distinct from
each other.

7. Anterior lobe:
 It is highly cellular and occasionally presents an intra-
glandular cleft. The part of the gland behind the cleft is
known as pars intermedia which is rudimentary in man and
embraces the front and side of the posterior lobe. The part
extending upward along the infundibular stem is known as
pars tuberalis.
The rest of the gland in front of the cleft is called pars anterior
(pars distalis). Therefore the adeno-hypophysis consists of
three parts—pars anterior, pars tuberalis and pars intermedia.

8. Posterior lobe:
 It is continuous above with the infundibulum
which extends downward and forward from the
floor of third ventricle and enters the hypophyseal
fossa through an aperture in diaphragma sellae.
 The neuro-hypophysis consists of three parts—
median eminence of tuber cinerium, infundibular
stem and pars nervosa. The infundi-bular stem
possesses an anterior covering of pars tuberalis and
rest belongs to the neuro-hypophysis.

9. Anterior lobe:
 The parenchyma of the anterior lobe consists of
irregular clusters of epithelial cells supported by
reticular fibres and permeated by sinusoids and
fenestrated capillary plexuses. The cells consist mainly
of two types— chromophobes and chromophils.
 Chromophobes include 50% of the cells presenting
agranular cytoplasm.
 Chromophils belong to the remaining 50% of cells.
According to the staining of the cytoplasmic granules,
the chromophils are subdivided into acidophil (alpha)
and basophil (beta) cells.

10. (a)
Acidophils comprise about 40% of parenchymal
cells.. They secrete growth hormone and prolactin,
both of which are simple polypeptides.
Orangeophil cells secrete growth hormone (GH or
STH); hence they are called the somatotrophs.
(b)
The basophil cells secrete most of trophic hormones
which are glycoproteins. These include thyroid
stimulating hormone (TSH), follicle stimulating
hormone (FSH), leutinizing hormone (LH) in female
or interstitial cells stimulating hormone (ICSH) in
male.

11. Blue arrow: acidophils
Red arrow: basophils
Yellow arrow: chromophobes

12. Posterior lobe:
 It consists of unmyelinated nerve fibres, fenestrated
plexus of blood capillaries and some special types of
neuroglial cells known as pituicytes. The nerve fibres
present knob-like terminals, the Herring bodies, which
contain membrane-bound secretory vesicles and abut
on the surface, of capillaries. The posterior lobe is
devoid of blood-brain barrier.

13. POSTERIOR LOBE HISTOLOGY

14. HORMONES RELEASED BY ANTERIOR PITUITARY
1. Thyrotropin releasing hormone (TRH) is a tripeptide and
secreted by the dorso-medial nucleus.
2.Luteinising releasing hormone (LHRH) is a decapeptide
and is synthesized in the preoptic area and anterior
hypothalamus. It stimulates the secretion of LH as well as
FSH.
3. Corticotropin releasing hormone (CRH) is produced by
the cells in the supra-optic and paraventricular nuclei.
4. Growth releasing hormone (GRH) is secreted by the
ventro-medial nucleus.

15.  5. Growth inhibiting hormone (GIH) also known
as somatostatin is secreted by the periventricular
nucleus and is a tetra-decapeptide.
 6. Prolactin releasing hormone (PRH) the location
of secreting neurons is not yet known.
 7. Prolactin inhibiting hormone (PIH) is
synthesized by the arcuate nucleus which is
dopaminergic. Dopamine inhibits prolactin release
by means of axo-axonic synapses.

16. HORMONES RELEASED BY POSTERIOR LOBE:
1.OXYTOCIN
2.ANTI DIURETIC
HORMONE

18. The anterior lobe is supplied by the superior hypophyseal
artery, a branch of internal carotid, which enters the pars
tuberalis and breaks up into tufts of capillaries in the
median eminence and infundibular stems.

19. There is definite control of nervous
control to anterior lobe but only few
fibres from hypothalamo hypophyseal
tract of nerve fibres or carotid plexus of
cervical sympathatic has been traced.

20.  The posterior lobe is supplied by the hypothalamo-
hypophyseal tract, which consists of a bundle of
about 100,000 unmyelinated nerve fibres derived
from the supraoptic and para-ventricular nuclei of
the hypothalamus.
 The fibres of the tract reach the neurohypophysis
through the infundibular stem and divide into a
series of distended Herring bodies containing
neuro-secretory vesicles of the hypothalamus.
.

21. • Adenoma
• Craniopharyngeoma.
•Pharyngeal hypophysis.

22.  A pituitary adenoma is a neoplasm of the pituitary gland.
These tumours are usually benign and can be divided into
two categories: non-functional tumours and hormone
secreting tumours.
 As the tumour increases in size, it can compress surrounding
structures, such as the optic chiasm. A lesion of the optic
chiasm characteristically produces a visual defect known as
a bitemporal hemianopia. A pituitary tumour can also cause
excessive hormone production, or insufficient hormone
production (by destroying the normal glandular tissue).
 Definitive treatment of a pituitary adenoma is via trans-
sphenoidal surgery. This technique involves gaining access
to the gland via the nasal cavity and sphenoid sinus (which
is located immediately inferiorly to the gland)

24.  Craniopharyngiomas are benign brain tumors
arising near the pituitary gland & may cause loss
of pituitary hormonal function, visual loss &
headaches.
 The initial optimal treatment for
craniopharyngiomas is maximal safe surgical
removal. Fortunately for most patients,
craniopharyngiomas can be removed through a
keyhole route via the nose using an endoscopic
endonasal approach or an eyebrow craniotomy..

27.  1.B D Chaurasias dental anatomy
 2.Hormones: Definition, Properties and Chemical
Natures of Hormones
 3.Useful Notes on the Structure of Bone Marrow |
General Anatomy
4.Article July 24, 1909
 THE HYPOPHYSIS CEREBRI CLINICAL ASPECTS OF
HYPERPITUITARISM AND OF HYPOPITUITARISM
 HARVEY CUSHING, M.D.