Histology of the Organs of Smell and Taste

Histology of the Organs of Smell and Taste

Follow protocol Notebook Illustrations

Slide 12. Olfactory epithelium (H 1042), ( MF 9th, page 237, 249)

The olfactory mucosa is a pseudostratified ciliated columnar epithelium located in the superior-most region of the nasal cavity, and contains bipolar olfactory cells whose cilia are embedded in mucus. Chemicals which dissolve in the mucus trigger responses in these cilia which initiate a nervous impulse, interpreted in the brain as an odor. Supporting cells surround the olfactory cells. Mucus-producing Bowman’s glands are embedded in the lamina propria. This connective tissue is richly vascularized. Some slides have portions of the cribriform plate of the ethmoid bone included.

olfactory_membrane_40x_PC271526
Olfactory membrane, 40x

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Olfactory membrane 100x

Here is a labeled view of the olfactory epithelium
Olfactory epithelium and underlying lamina propria, 100x:
olfactory epithelium: 
olfactory cells (with deep nuclei)
cilia
supportive cells (with superficial nuclei)
surface mucus
(looks like a line above surface)
lamina propria:
glands of Bowman (serous)
ducts of these glands
arterioles
venules
[The ethmoid bone is present on some slides, appearing blue.]

olfactory_membrane_100x_PC271529
Olfactory epithelium and underlying lamina propria, 100x:
Showing details of glands in the lamina propria

olfactory_membrane_400x_PC271528

Olfactory epithelium, 400x
Note the prominent stereocilia

olfactory_membrane_400x_PC271530

Olfactory epithelium, 400x
opening of a ducts through the epithelium

Slide 13: Tongue, taste buds rabbit (70771), ( MF 9th, page 157)

Taste transducing cells are located in taste buds which line the sides of papillae located on the tongue. Microvilli on the surface of the transducing cells react with sweet, salty, acidic or bitter substances to generate a nervous impulse, interpreted in the brain with its specific taste. (Remember that flavor combines taste and odor.) Make two illustrations on the same page one at 100x and one at 400x:

taste_bud_papillae_40x_PC271531
taste buds, 40x

Edge of tongue, showing papillae and striated muscle, 40x

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Here is a labeled view of the taste bud papillae
Taste Bud Papillae: 100x:
fungiform papilla
stratified squamous epithelium
taste buds
taste pore
excretory duct [fr. serous alveoli]
nerve tracts
striated muscle
circular furrow (“trench” between papillae)

Here is a labeled version of the taste bud, Verhoef Stain, 400x, .
a Taste Bud: ( MF 9th, page 159), 400x:
taste buds
taste pore
taste hairs (microvilli)
lingual mucosa (surrounds buds)
lamina propria

Slide 10: Vater-Pacini corpuscles, pancreas, H-eosin (H 1688)
Pressure detection: Pacinian Corpuscles in the pancreas: Pacinian corpuscles are specialized nerve endings which detect pressure and vibration in an organ.

Pacinian_corpuscles_PC271521

Here is a labeled view of Pacinian corpuscles.
Pacinian Corpuscles (MF 9 th: page 229 and 147) at 100x:
Pacinian corpuscle:
connective tissue capsule
central cavity with numerous lamellae (with flattened nuclei)
naked dendrite
pancreatic acini

Histology of the Inner Ear

Histology of the Inner Ear

Follow protocol Notebook Illustrations

Above left are the three ossicles photographed with a dime to show their relative size. The left most bone is the malleus (hammer) which is attached directly to the typmanic membrane. It transmits vibrations to the incus (anvil) which in turn transmits vibrations to the right most bone, the stapes (stirrup). The flat end of the stapes fits into the oval window of the cochlea which then transmits vibrations into the cochlea along the scala vestibuli.

Examine the following two slides, note the features in common and the differentiating features. Illustrate each at the noted power to take up a page. Compare with the illustrations in di Fiore’s Atlas of Normal Human Histology, 9th Ed.

Slide 9: Ear, cochlea., guinea pig, (71571) Two views, and overview, and a detail: (see MF 9th, page 347, fig. 19-7 & fig 19-9)

cochlear_nerve_40x_P2182170
Cochlea cross section, Overview at 40x:
helicotrema
scala vestibuli (from oval window)
vestibular membrane
scala tympani (to round window)
basilar membrane
cochlear duct
organ of corti
osseus labyrinth (bony case)
spiral lamina (bony core)
spiral ganglion
cochlear nerve (visible in some)
Here is a labeled view of the 40x view including the cochlear nerve.
cochlea_P2171518md

Cochlea, showing helicotrema and an intact set of membranes:
vestibular membrane
basilar membrane

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cross section through cochlear loop

Cochlear duct detail, 100x: (MF 9th, page 347, fig 19-8.)
organ of corti
tectorial membrane
hair cells (orange at tips)
internal spiral sulcus
basilar membrane
spiral ligament
cochlear duct Here is the image labeled .
endolymph
vestibular membrane
scala vestibuli
scala tympani
perilymph
osseus spiral lamina
spiral ganglion

Organ_of_Corti_P2171518

Organ of Corti
organ of corti
tectorial membrane
hair cells (orange at tips)
internal spiral sulcus
basilar membrane
spiral ligament
cochlear duct
endolymph
vestibular membrane
osseus spiral lamina

Slide 11. Crista ampullaris (H 1697)

The semicircular canals detect angular or rotational acceleration. This is a cross section through an ampulla of a semicircular duct. (There is no illustration in di Fiore.)
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Semicircular Canal, 40x, cross section
Note boney labyrinth surrounding the canal

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Crista Ampullaris, 100x:
crista ampullaris (ridge-like structure)
receptor epithelium (hair cells on crista)
cupola (gelatinous mass on top of the crista)
ampulla of semicircular duct
endolymph (fills the chamber)
membranous labyrinth Here is a labeled view of the crista ampullaris.

crista_ampullaris_200x_PC271525
Crista Ampullaris, 400x
Hair cells can be made out.

Histology of the Eye

Histology of the Eye

Follow protocol Notebook Illustrations

This is another slide in which, because of the size of the specimen, you will have to move around to see the entire structure, even at the lowest power. First look at the slide with the naked eye to orient yourself to its gross features: you should be able to see the cornea, lens (often fragmented on the interior), cavities, and ciliary bodies. Note that some slides are oriented R and L, others up and down…

With the 4x objective, find the sclera and follow it around the entire perimeter, identifying the regions as you come to them and noting the layers in each region. Again, identify all features listed before you begin an illustration. You will make three illustrations:

  1. The gross anatomy of the anterior portion
  2. A low power view of the rear wall
  3. A high power view of the retina:

Slide 8:  Eye, Monkey, general structure, sagittal section, general features H 1064  (MF 4th, page 343, 345)

Eyeball_PC271488
Section through the eye optic nerve on the left,25x

At 25x: Gross anatomy of section through the eye:    (Here is a labeled version of the eye section.)
FIBROUS TUNIC
cornea (anterior 1/6th)
sclera (posterior 5/6ths)
ocular conjunctiva
corneal limbus (cornea & sclera join)
canal of Schlemm (poss. not visible)

VASCULAR TUNIC:
ciliary body:
ciliary muscle
ciliary processes
iris
pupil

NERVOUS TUNIC:
retina
lens (It is often fragmented during slide preparation, and only the outline remains.)
suspensory ligaments (not visible?)
anterior cavity
anterior chamber
posterior chamber
aqueous humor
posterior cavity
vitreous humor

eyeball_anterior_half_PC271489

At 40x: Gross anatomy of anterior portion of the eye
Here is a labeled view of the anterior portion of the eye.

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VASCULAR TUNIC, 60x:
ciliary body:
ciliary muscle
ciliary processes
iris
pupil

vascular_tunic_PC271519

VASCULAR TUNIC, 100x: (Here is a labeled version of the anterior vascular tunic and fibrous tunic.)
 ciliary body:
ciliary muscle
ciliary processes
iris
pupil

cornea_200x_PC271515

400x view of cornea, left to right:
posterior epithelium (low cuboidal cells)
Corneal stroma withkeratocytes embedded in collagen fibers
anterior epithelium (stratified squamous epithelium)

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At 100x: cross section through rear wall of eye with optic nerve: Here is a labeled view of the rear wall.
 left to right:
optic nerve with parallel axons from ganglion cells
optic disc  (note photoreceptors are absent in retina where the optic nerve is attached)  adventitia (orbital fatty tissue)
sclera
choroid, with melanocytes
retina:
cell bodies of
photoreceptors
bipolar cells
ganglion cells
Here is an extraordinarily good image of the blind spot where the optic nerve exits the rear of the eye.

eye_rear_wallPC271514

300x:  view through the rear wall of the eye showing, top to bottom:
Nervous tunic
ganglion cell bodies
bipolar cell bodies
photoreceptor cell bodies
Vascular tunic:
pigmented cells of choroid
choroid
Fibrous tunic:
sclera

retina_PC271518
Section through the retina 400x

400x view of cross section of retina:     (Here is a labeled version of the cross section of the retina.)
Deep to superficial tissues (left to right):
pigment cells
rods (finer and longer)
cones (thicker and shorter)
outer limiting membrane
nuclei of cones (closer to choroid)
nuclei of rods (further from choroid)
nuclei of:
horizontal cells (closest to receptors)
bipolar cells
amacrine cells (closest to ganglion)
ganglion cell bodiesMullers fibers (vertical fr ganglion cells)

Other images related to the eye: