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SOME MACROSCOPIC AND MICROSCOPIC OBSERVATION
ON THE PITUITARY GLAND OF GUINEA-PIG Cavia culteri
Luay O. H.
Department of Anatomy , Histology and Embryology , College of Veterinary
Medicine , University of Baghdad , Baghdad , Iraq .
(Received 29 November 2016, Accepted 10 December 2006)
Keywords: Guinea pig, Pituitary gland, Sphenoid bone .
ABSTRACT
This research was conducted to asses some macroscopical and microscopical
observations of pituitary gland in guinea pig .
Pitutary gland is considered as a complex endocrine gland , located at the base of the
brain where it lies in the sella turcica , a small deprission in the sphenoid bone .
It is attached to the hypothalamic region of the brain by a narrow stalk . The glands
weight about ( 20 mg ) . microscopically it is composed of an epithelial component or
adenohypophyis and a nervous component or neurohypophysis . The parancymal cells
of the pars distalis are the chromophilic cells . Pars intermedia consist of
chromophobic cells and basophilic cells . neurohypophysis has scattered pituicytes
among the nerve fibers .
INTRODUCTION
The hypophysis or pituitary gland is a complex endocrine gland , lies in a
small deprission in the sphenoid bone . The parenchymal cells of pituitary gland
synthesize hormones which may regulate specific tissue or organs of the body or
which may have a more general systemic effect ( 1 ,2 ) .
These hormones have also important function in the regulation of metabolism ,
growth and reproduction . The aim of this research is to study some macroscopic and
microscopic observations of the piuitary gland in guinea-pig .
MATERIAL AND METHODS
Hypopysis were dissected out in this study . Macroscopical obervations of
thier location, shape and size were noticed.
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The gland were weighted , rinsed with 9% normal saline . For light microscopy ,
specimens were fixed with Bouins fluid for 24 hours then dehydrate in graded ethanol
and embedded in paraffin . They were cut serially at 6micrometerand stained with
hematoxyline and eosine ( 3 ) and examined with olympic microscope .
RESULT AND DISCUSSION
Pitutary gland of guinea-pig was located at the base of the brain weighting
approximatelly 20 mg and about 6 m in lenght , 3 m in width .
It has neural and vascular connections with the brain . This is in accordance with (1 ,
2 , 4 , 5) in equine , ruminant , carnivorse and pig .
Microscopically , pituitary gland is subdivided into adenohypophysis and
neurohypophysis .
Three subdivided ( pars distalis , pars tueralis & ars intermedia ) of the adenoyppysis
were distiguished , pars distalis , pars tuberalis and pars intermedia ( plate 1 ) . The
neurohypophysis are also subdivided into three region , median eminennce , the
infundibular strem and a thin investement of glandular tissue of pars tuberalis .
The stroma of pars distalis is composed of irregular cords or clusters of glandular cells
which surrounded by delicate connective tissue fiber and separated from each other by
thin-walled sinusoids . ( 5 , 6 ) interpratate that these sinusoid lined by fenestrated
endothelium and their pras faclitate the diffussion of blood bearing releasing factor
into the gland and allowed the protein secretory products of thier cells into the blood .
According to staining with acid or basic dyes , the cells of pars distalis were
designated as acidophilic or basophils . Other cells that showed little or no
cytoplasmic staining were known as chromophobe . It become evident by some
authors that there were more cell types than acidophils , basophils , and
chromophobes on the basis of the size and shape of their secretory granules as
thyrotrophs cells , gonadotrophs cells and corticotrophs cells ( 7 , 8 , 9 , 10 ) .
Acidophilic cells are relatively large , rounded or ovoid cells . These cells tend to be
more scattered with in te parenchyma of this pars distalis .
Basophil cells can be most easily distinguished from acidophils by their blue stained
cytoplasm . These cells are larger than most acidophlic cells and are round or ovoid in
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shape . They are most numerous in the central anterior portion of the pars distalis .
They form small groups situated deep at some distance from sinusoids . Their
granules are the smallest of any granules found in the parencymal cells of the
hypopysis .
Chromophobe cells are much less numerous than previous cells and appeared as
groups of small cells . They show little affinity for dyes in histological section . These
cells occasionally reach the size of acidophils and basophils . They were devoid of
secretory granules . ( 7 , 8 ) were considered these cells as to be reserve cells capable
of differentiating into either acidopils or basophils ( fig. 1, 2 ) .
The distinct area in this gland is the pars intermedia . This area is separated from pars
distalis by a narrow cleft . This interlobar cleft is represented by scattered colloid –
filled vesicales . Pars intermedia consist of chromophobe and basophil cells . The pars
intermedia is beleived to be responsible for the secretion of melanocyte stimulating
hormone which is thought to be involved in melanine production ( 1 , 2 , 7 ) .
The greater part of the pituitary gland is the neurohypophysis which consist of
unmyelinated nerve fibers . These fibers are in close proximatelly to capillaries which
from a rich plexus in this region . Cells of pituicytes were scatered among these nerve
fibers . these pituicytes were varies in size and shape ( fig. 3 ) .
( 11,12,13,14,15,16 ) claimed that pituicytes are considered to be equivalent to
neuroglial cells in the central nervous system , but whether they have a supportive
function only or activelly participates in the secretory process of adjacent nerve
terminal is not known .
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Fig 1 : The parts of pituitary gland in guinea–pig
Fig1:Adenohypophysis of Pituitary gland in guinea pigs A-Acidophilic cells
Basophilic cells C-Chromatophobes cells
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Fig 2:Anterior part of pituitary gland in guinea pig
Fig3:Neurohypophysis of pituitary gland in guinea pig A-unmylinated nerve fibers
B-Capillaries C-pituicytes
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بعض الرؤى العیانیة والمجھریة للغدة النخامیة فی خنزیر غینیا
لؤی عبید حمزة
فرع التشریح والانسجة والاجنة ، کلیة الطب البیطری ، جامعة بغداد ، بغداد ، العراق .
الخلاصة
یتضمن ھذا البحث رؤى عیانیة ومجھریة للغدة النخامیة فی خنزیر غینیا .تعد الغدة النخامیة ، غدة
والذی یمثل انخفاض Sphnoid bone . صماء معقدة الترکیب تقع فی قاعدة الدماغ تضطجع على السرج
الترکی وترتبط النخامیة مع منطقة تحت المھاد بواسطة ساق نحیفة . Sella tursica صغیر فی العظم الاسفنجی
تتکون الغدة مجھریا من جزء ظھاری Adenohypophysis تزن الغدة حوالی 20 ملیغرام. وجزء عصبی
یتکون الجزء الوسطی من . Neurohypophysis. .یتکون متن الجزء القاصی من خلایا محبة وخلایا کارھة
نخامیة Pituicytes. خلایا کارھة وخلایا قعدیة . یحتوی الجزء العصبی على خلایا تتخللھا الیاف عصبیة
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