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TOPIC 3:HISTOLOGY 

I. GENERAL OBJECTIVEAfter nishing laboratory activity, the students will have a comprehensive

knowledge about microstructure histology of endocrine glandsII. SPECIFIC OBJECTIVESAt the end of laboratory activity, the students will be able to :

1. Analyze the structural dierences within the anterior and posterior lobesassociated with their functions.

. !"plain the microscopical structure of pituitary gland: type of cells andtheir characteristics of   adenohypophysis, general microstructure of neurohypophysis.

#. !"plain the microscopical structure thyroid gland: type of cells and theircharacteristics

$. !"plain the microscopical structure of pancreas gland: islet of %angerhans

&. Analyze the structural dierences betwen endocrine and e"ocrinestructure in pancreas. !"plain microstructure of islet of langerhans and $type cell's.

(. !"plain the microscopical structure of adrenal gland: cortical zones,medulla

Methodsa. )resentationb. *elf directed learning Laboratory fac!tes

a. +iomedical %aboratoryb. utors-trainersc. odels : Atlas, )osters, )reparats, icroscopesd. *tudent %earning /uidee. rainer's /uidef. 0eferences

Ve"#e +iomedical %aboratoryE$a!#ato"a. )oint nodal evaluationb. %aboratory e"amination

 0eferences:

1. !mbriology. Anatomy#. istology

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%&POP%&SIS

GAMBAR '. %&PO%&SIS

  Pt#tary (ars a"teror Pt#tary (ars(osteror

  )ade"ohy(o(hyss*

)"e#rohy(o(hyss*

Ne#rohy(o(h

Ade"ohy(o(h

)ars 2nfudibulu

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Ga+bar ,

 he pituitary gland is suspended by a stalk from the hypothalamus atthe base of the diencephalons. 2t rests in a saddlelike depression in thesphenoid bone called the sella tursica, behind the optic chiasm. 2ts ma3ordivisions, the anterior ade"ohy(o(hyss  and the posterior"e#rohy(o(hyss- dier in embryonic origin, structure, and function.

Ade"ohy(o(hyss

 he adenohypophysis is composed of cords of glandular ephitelial cellsseparated by the numerous sinusoidal capillaries of the secondary ple"us.

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2t is not directly innervated by hypothalamic nerves, but only byautonomic bers from the carotid ple"us.

/ambar $. Adenohypophysis 14445

Ne#rohy(o(hyss

 he "f#db#!#+ consists of the "f#db#!ar ste+ )"e#ra! sta!* andthe +eda" e+"e"ce. he stem carries a"ons from the hypothalamus to thepars nervosa and contains capillary loops of the primary capillary ple"us. hemedian eminence of the t#ber c"ere#+ forms the 6oor of thehypothalamus. he  (ars "er$osa )"f#db#!ar (rocess*  is the e"pandedlobe of the neurohypophysis7 it contains a"on terminals and numerouscapillaries.

/ambar &. 8erohypophysis 1444"

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A/ENO%&POP%&SIS

A. Pars /sta!s0

'. Chro+o(hobes. hese cells stain poorly and appear clear or white intissue sections. hese stellate cells may have some phagocyticfunctions.

,. Chro+o(h!s. here is a specipic cell type for each hormone. 9suallylarger than chromophobes, chromophils are subdivided into classes:

a. Acdo(h!s.  hese cells secrete simple proteins. hey stainintensely with eosin and orange /, but not with )A*. ore abundantin the periphery of the gland, they are usually smaller thanbasophils and their granules are larger and more numerous. heacidophils include ma3or types of hormonesecreting cells:

so+atotro(es- which produce 1ro2th hor+o"e )G%-so+atotro("*- and +a++otro(es- which produce (ro!act".;A simple mnemonic device for remembering the hormonessecreted by acidophils is GPA  < growth hormone,  proplactin,acidphils.=

b. Baso(h!s. ore abundant in he core of the gland, they are usuallylarger than acidophils, with fewer and smaller granules. he #ma3or types of hormone < producing basophils:

!ach of the types of 1o"adotro(es produces a dierent

gonadotropin. >ne produces fo!!c!e3st+#!at"1 hor+o"e

)FS%*7 the other produces !#te"4"1 hor+o"e )L%5 called"terstta! ce!!3st+#!at"1 hor+o"e )ICS%* in males=.

Cortcotro(es produce adre"ocortcotro(" )ACT%*.

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Thyrotro(es produce thyrotro(" )thyrod3st+#!at"1

hor+o"e- TS%*.

B. Pars T#bera!s0  his funnelshaped superior e"tension of the parsdistalis surrounds the infundibular stem. 2ts histology is similar to the pars

distalis, but it contains mostly gonadotropes. he pars tuberalis containsmany capillaries of the primary capillary ple"us of the hypophyseal portalsystem;lihat gambar 1=

C. Pars I"ter+eda0 his is a band or wedge of adenohypophysis betweenthe pars distalis and pars nervosa7 it is rudimentary in humans. 2t containsRathe6s cysts- small, irregular, colloidcontaining cavities lined withcuboidal epithelium that are the remnants or 0athke's pouch. 2t alsocontains scattered clumps and cords of basophilic cells, or melanotropes,

which secrete melanocytestimulating hormone ;β*=.

NE7RO%&POP%&SIS

 he neurohypophysis has # ma3or structural components: a"ons,capillaries, and pituicytes.

A. A8o"s of Ne#rosecretory Ce!!s0  he neurohypophysis stainspoorly if at all. 2t contains many unmyelinated a"ons whose cell bodies;soma= are located mainly in the s#(rao(tc  and (ara$e"trc#!ar"#c!e of the hypothalamus. A"ons passing from these nuclei to the parsnervosa are together termed the hypothalamohypophyseal tract. hea"ons contain neurosecretory granules and e"hibit large granule < lled

dilations called %err"1 bodes. he neurosecretory materials in thesegranules, synthesized and packaged in the above < mentioned cell bodies,include the following products:

'. Ne#rohy(o(hysea! hor+o"e.  he hypothalamic neurons thatterminate in the neurohypophysis release o"ytocin and antidiuretichormone around the capillaries in this part of the pituitary. O8ytoc"is a ?aminoacid peptide synthesized mainly by cells of theparaventricular nucleus. 2t stimulates milk e3ection by the mammaryglands and stimulates the contraction of uterine smooth muscleduring copulation and childbirth. A"td#retc  hor+o"e )A/%-ar1""e $aso(ress"* is ?aminoacid peptide synthesized mainly

by cells in the supraoptic nucleus. 2t stimulates water resorption bythe renal medullary collecting ducts and contraction of vascularsmooth muscle.

,. Ne#ro(hys" is a binding protein that comple"es withneurohypophyseal hormones.

9. ATP )ade"os"e tr(hos(hate*  acts as a source of chemicalenergy for the neurosecretory process.

B. Fe"estrated Ca(!!ary P!e8#s0  *urrounding the a"onterminals in the pars nervosa, these capillaries pick up the neurosecretoryproducts and convey them to the general circulation.

C. Pt#cytes0  hese are highly branched glial cells whoseprocesses surround and support the unmyelinated a"ons.

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Histology of thyroid

Pituicyt Ca(!!ar

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Gambar. Kelenjar Tiroid dan Parathyroid 40X

Thyroid tissue is composed of thousands of follicles that consist of spheres formedby simple epithelium whose lumen contains a gelatinous substance called colloid. Insections, follicular cells range from squamous to columnar and the collicles have anextremely variable diameter. The gland is covered by a loose connective tissue capsulethat sends septa into the parenchyma. As these septa gradually become thinner theyreach all the follicles, separated from one another by fine, irregular connective tissuecomposed mainly of reticular fibers. The thyroid is an extremely vascularized organ, withan exensive blood and lymphatic capillary networ surrounding the follicles. !ndothelial

cells of these capillaries are fenestrated, as they are in other endocrine glands. Thisconfiguration facilitates the transport of molecules between the gland cells the bloodcapillaries.

The morphologic appearance of thyroid follicles varies according to the region of the gland and its functional activity. In the same gland, larger follicles that are full of colloidand have a cuboidal or squamous epithelium are found alongside follicles that are lined bycolumnar epithelium. "espite this variation, the gland is considered hypoactive when theaverage composition of these follicles is squamous. Thyrotropin stimulates the synthesisof thyroid hormone, increases the height of the follicular epithelium, and decreases thequantity of the colloid and the size of the follicles. The cells membrane of the basal portionof follicular cells is rich in receptors for thyrotropin.

The thyroid epithelium rests on a basal lamina. The follicular epithelium exhibits all

the characteristics of a cell that simultaneously synthesizes, secretes, absorbs, anddigests proteins. The basal part of these cells is rich in rough endoplasmic reticulum. Thenucleus is generally round and situated in the center of the cell. The apical pole has adiscrete #olgi complex and small secretory granules with the morphologic characteristics

Parathyr

:e!e";ar

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of follicular colloid. Abundant lysosomes, $.%&$.' (m in diameter, and some largephagosomes are found in this region. )itochondria and cisternae of rough endoplasmicreticulum are dispersed throughout the cytoplasm.

#ambar. *oliel Thyroid +$$$x

 Another type of cell, the parafollicular, of cell, is found as part of the follicular epithelium or as isolated clusters between thyroid follicles. Parafollicular cells aresomewhat larger than thyroid follicular cells and stain less intensely. They have a smallamount of rough endoplasmic reticulum, long mitochondria, and a large #olgi complex.The most striing feature of these cells is their numerous small granules containinghormone. These cells are responsible for the synthesis and secretion of calcitonin, ahormone whose main effect is to lower blood calcium levels by inhibiting bone resorption.-ecretion of calcitonin is triggered by an elevation in blood calcium concentration.

Histology of parathyroid

:o!o

Se! Se!

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The parathyroids are small glands / 0x' mm / with a total weight of about $. g.They are located behind the thyroid gland, one at each end of the upper and lower poles,usually in the capsule that covers the lobes of the thyroid. -ometimes they are embedded

in the thyroid gland.!ach parathyroid gland is contained within a connective tissue capsule. Thesecapsules send septa into the glands, where they merge with the reticular fibers thatsupport elongated cordlie clusters of secretory cells.

The endocrine cells of the parathyroid are arranged in cords. There are 1 types of cells2 the chief, or principal, cells and the oxyphil cells.

Gambar. Adrenal 40x

The chief cells are small polygonal cells with a vesicular nucleus and a pale / staining,slightly acidophilic cytoplasm. !lectron microscopy shows irregularly shaped granules

31$$&$$ nm in diameter4 in their cytoplasm. They are the secretory granules containingparathyroid hormone, which is a polypeptide in its active form. 5xyphil cells constitute asmaller population. They are larger polygonal cells, and their cytoplasm contains manyacidophilic mitochondria with abundant cristae. The function of the oxyphil cells is notnown.

6ith increasing age, secretory cells are replaced with adipocytes. Adipose cellsconstitute more than %$7 of the gland in older people.

@apsul

ona

ona

ona

edull

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Gambar Cortex Adrenal 00X

A!"#$A% &'(P"A"#$A%) G%A$!'The gland consists of 1 concentric layers2 a yellow peripheral layer, the arenal*ortex8 and a reddish&brown central layer, the adrenal med+lla

Adrenal Cortex9ecause of the differences in disposition and appearance of its cells, the adrenal

cortex can be subdivided into 0 concentric layers whose limits are usually not sharplydefined in humans2 the ,ona glomer+losa- the ,ona fas*i*+late, and the  ,onareti*+laris. These layers occupy +% 7, '% 7, and : 7, respectively, of the total volume of the adrenal glands.

The layer immediately beneath the connective tissue capsule is the zonaglomerulosa, in which columnar or pyramidal cells are arranged in closely, paced, or arched cords surrounded by capillaries.

The next layer of cells is nown as the zona fasciculata because of thearrangement of the cells in straight cords, one or two cells thic, that run at right angles tothe surface of the organ and have capillaries between them. The cells of the zonafasciculate are polyhedral, with a great number of lipid droplets in their cytoplasm. As aresult of the dissolution of the lipids during tissue preparation, the fasciculate cells appear vacuolated in common histologic preparations. 9ecause of their vacuolization, the cells of the fasciculate are also called spongyo*ytes.

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#ambar zona *asciculata +$$$; 3tampa sel dengan gambaran sponge di sitoplasma4The zona reticularis, the innermost layer of the cortex, lies between the zona

fasciculata and the medulla8 it contains cells disposed in irregular cords that form ananastomosing networ. These cells are smaller than those of the other two layers.

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H/'T%G1 2 /'%#T 2 %A$G#"HA$'

Is!et of 

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/slet of %angerhans 400x

Islet 5f

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the cells in the islet, are stained brown in micrograph. 9eta cells are distributed throughoutthe islet while in contrast, glucagons&producing alpha cells 3about 1%7 of the total4 arearranged around the periphery. 5ther hormone&producing cells are unstained in thesemicrographs. The close proximity of these cells facilitates their interaction for control of 

blood glucose levels and other metabolic function.