Lymphatic System

Lymphatic System

The lymphatic system collects and cleanses the fluid which seeps out of the capillary beds, bathing the tissue which it perfuses. This cleansing fluid, called lymph, is collected by afferent lymph vessels which carry it to a lymph node where it is filtered. There, macrophages consume bacteria and debris, and immune cells monitor the lymph for antigens which might react with their antibodies and stimulate them to multiply and make antibodies. The cleansed lymph leaves via an efferent lymph vessel.
In the abdomen, cleansed lymph from the intestines is collected in the cysterna chyli, and, except for the upper R quadrant of the body, is collected into the thoracic duct which empties into the circulatory system through the L subclavian vein. (The upper right quadrant drains by the R lymphatic duct  into the R subclavian vein.)

[Gilbert has no relevant illustrations.]

ANATOMY: Illustrate the highlighted features of the lymphatic system in the cat:

mesenteries_P4113366

The hepatic portal system has been injected with yellow latex, showing the venous drainage from the intestines to the liver.
The lymphatic drainage follows the same pattern as the arterial (red) and venous drainage sytems (yellow in the case of the hepatic portal system). Examine the relationship of the mesenteries to the small intestine in the dissected cat.
[Thanks to Professor Brian W. Witz at the Nazareth College of Rochester for correcting identifications of some of the features of the lymphatic system on this page.]

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Small afferent lymph vessels (difficult to see) lead to lymph nodes. Once filtered, lymph is carried by the efferent vessels which empty into the cisterna chyli, located behind the abdominal aorta.

thoracic_duct_P4113367
As the cisterni chyli passes through the diaphragm, it becomes the thoracic duct. In the thorax, it may be seen as a thin brown tube to the left of the aorta, under the parietal pleura and the intercostal arteries.


Trace the throacic duct up until it passes behind the left subclavian vein into which it empties (next to the jugular vein).
Note also these lymph nodes:
the submandibular (and another view of both the R and L submandibular lymph nodes.)
the numerous lymph nodes associated with the ileocecal junction .
HISTOLOGY OF A LYMPH NODE:

Examine and illustrate the following slide, labeling the specified features. Note the function of each feature. It is specially stained with silver and gold to show reticular fibers. The plate numbers are in the 9th Ed. of di Fiore’s Atlas of Normal Histology:

Slide 3. Lymph node, Reticular tissue, (H 550) VE: p. 125 & 127, 40x:

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Here is a 40x view of a lymph node , and its medulla
[ Here is a labeled version.]
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At 100x, one can see the subcapsular sinus more clearly and the medulary sinus is at the bottom of the image.

lymph_node_400x_capsule_P4113347

CORTEX:
At 400 x, details of the capsule become clearer.
Note the space under the capsule, the subcapsular sinus , which contains the lymph within the node.
lymph_node_400x_P4113348

A close-up of a germinal center:
trabeculae form baffles which direct lymph over the germinal centers
germinal centers house immune cells, enlarge during infections
[Here is a labeled version of the image.]
lymph_node_100x_medullary_sinus_P4113350

MEDULLA:
medullary sinus chamber (s) in the center, collects filtered lymph
reticular fibers give structure to the gland, anchor macrophages, (best seen at 400x)
Here are additional images similar to the ones above, but with slightly different views.

Organs of Respiration in the Cat

Organs of Respiration in the Cat

Examine these slide at low power first to find the field which best demonstrates the listed features. Label the indicated features, and briefly describe their functions.

Locate and examine the following organs of the respiratory tract in the cat. Review the function of each as you locate them.

Here is an image of fresh lungs deflated and then inflated to show the dramatic difference in volume.

(See Gilbert, Pictorial Anatomy of the Cat, pp 37-41)

Make three illustrations:
1) anterior view of entire respiratory system
2) view down into larynx
3) mid-sagittal section of head

1)  ANTERIOR VIEW OF WHOLE SYSTEM

 

Respiratory_Overview_P4210172_sm

Click to see a labeled view of the system.

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Clear away muscles to see: (Here is a labeled anterior view of the larynx.)
thyrohyoid membrane (connects the larynx to the hyoid bone)
larynx
thyroid cartilage (largest of the laryngeal cartilages, forms the front of the larynx)
cricoid cartilage (ring shaped cartilage upon which the larynx sits)
trachea
tracheal rings
esophagus (behind trachea)

bronchus_P4224026

R & L pleural cavities (Here is a labeled view of the thoracic respiratory organs.)
anterior lobes of R & L lungs (termed superior lobes in human)
middle lobes of R & L lungs (termed middle in human, L lacking)
posterior lobes of R & L lungs (termed inferior lobes in human)
pericardium
root of the lungs
bronchi (behind heart, esp on R side)
pulmonary ligament, attached to:
diaphragm
phrenic nerve
heart lung preparation

heart_lung_prep_P1010064

In butchering, the heart and lung are removed from the thorax as a unit. These images show the heart nestled between the right and left lungs of a goat.

Here are images of the same preparation inflated (1), and inflated (2).

2)  VIEW DOWN INTO LARYNX


Make a transverse cut through the thyrohyoid membrane and esophagus well above the top of the larynx. Do not cut the epiglottis. Lift the larynx up out of the throat. Snip the esophagus to open it up to below the larynx.
Draw:
epiglottis
arytenoid cartilage
false vocal cords
vocal cords
glottis
esophagus

Here is a labeled view down into the larynx.

3)  MID-SAGITTAL SECTION THROUGH THE HEAD AND NECK: (p. 39 in Gilbert)

Students may make this cut in order to view the following set of features. First, taking care to be exactly mid-sagittal, make a clean cut with a sharp scalpel through successive soft tissues of the tongue (from below) and pharynx to bone (through the neck to the vertebral column), then use a sharp hacksaw to cut through skull and vertebra. Wash the cut surfaces to view the features more clearly. Note that one half will show the nasal septum, the other the conchae.

If you do not make this cut, view a cat which has been so prepared. Each student should locate the following features on this mid-sagittal section:


external nares (external nose openings)
nasal conchae
hard palate
soft palate
eustachian tube opening (near the sella turcica)
nasopharynx (“pharynx” in cat)
sphenoid sinus (directly above nasopharynx)
palatine tonsils (lateral rear wall of the mouth)
genioglossus muscle (main muscle of tongue)
fenulum (membrane ties tongue down)
Here is a labeled view of a midsagittal section of the head.