Rat Dissection

Dorsal: toward the back
Ventral: toward the belly
Lateral: toward the sides
Median: near the middle
Anterior: toward the head
Posterior: toward the hind end (tail)
Superficial: on or near the surface
Deep: some distance below the
surface
Caudal: toward the tail end
Pectoral: chest and shoulder region
Pelvic: relating to the hip region
Dermal - relating to the skin
Longitudinal - lengthwise

cranial region – head
cervical region – neck
pectoral region - area where front legs attach
thoracic region - chest area
abdominal region - belly
pelvic region - area where the back legs attach

vibrissae - hairy coat that covers the rat and the sensory hairs (whiskers)
located on the rat's face

incisors: mouth has a large cleft in the upper lip which exposes large front….these incisors will continue to grow for as long as the rat lives

nictitating membrane: found at the inside corner of the eye. This membrane can be drawn across the eye for protection. The eyelids are like those found in humans

pinna: the ears are composed of the external part called the……

teats: located on the ventral surface, only females have it

anus: ventral to the base of the tail

vaginal opening:This will be seen between the anus, at the base of the tail, and the opening of the urethra, which is more ventral.

scrotal sacs: contain testes

prepuce: bulge of skin surrounding the penis

Excretory/Reproductive Systems
Kidneys: The liver has many functions, one of which is
to produce bile, which aids in digesting fat. The
liver also stores glycogen and transforms wastes into less harmful substances.
Adrenal glands
Renal Veins/Arteries: supply the kidneys with blood
Ureters: attach to the kidney and lead to the urinary bladder.
Urinary bladder: stores urine
Urethra: carries urine from the bladder to the urethral orifice
Testes: located in the scrotal sac, cut through the sac to find them
Epididymis: On the surface of the testis is a coiled tube which is known as the …. it also stores and collects sperm cells
Vas deferens: moves sperm from the epididymis to the urethra which carries sperm through the penis and out the body
Seminal vesicle: lumpy brown glands located to the left and right of the
Vagina: short gray tube lying dorsal to the urinary bladder is
the….
Uterine horns: there are two of these and they extend toward the kidneys
Ovaries: tips of the uterine horns are small lumpy glands that are known as

Oviducts: connected to the uterine horns

Digestive System
Coelom: body cavity within which the viscera (internal organs) are located
Liver: dark colored organ suspended just under the diaphragm. The liver has many functions, one of which is to produce bile, which aids in digesting fat. The liver also stores glycogen and transforms
wastes into less harmful substances.
Esophagus: runs through the diaphragm and moves food from the mouth to
the stomach. You can tell it apart from the trachea by its lack of cartilage rings
Stomach (Curvatures)
Spleen: same color as the liver, is attached to the greater curvature of the stomach and is
shaped like a banana. It is associated with the circulatory system and functions in the destruction of blood cells and blood storage. A person can live without a spleen, but they're more likely to get sick as it helps the immune system function.
Pancreas: is a brownish, flattened gland found in the
tissue between the stomach and small intestine. The
pancreas produces digestive enzymes that are sent to the
intestine via small ducts (the pancreatic duct). The
pancreas also secretes insulin, which is important in the
regulation of glucose metabolism.
Small intestine: slender coiled tube that receives partially digested food from the stomach (via the
pyloric sphincter). The term “small” refers to its diameter, not its length.
Mesentery: small intestine are held together by a membrane
Cecum: pouch that connects the large and small intestines. Food is temporarily stored in the cecum
while helpful bacteria digest the cellulose found in plant cells
Large intestine: large greenish tube that extends from the small intestine and leads to
the anus. The large intestine is also known as the colon. This is where the final stages of digestion and water
absorption occur and it contains a variety of bacteria to aid in digestion.
Rectum: the short,
terminal section of the colon that leads to the anus. The rectum temporarily stores feces before they are expelled
from the body.

Circulatory/Respiratory Systems
Soft/Hard Palates: softsoft palate and the ridged hard palate anterior to it
Salivary Glands: which are on the sides of the neck,
between muscles. Salivary glands are soft spongy tissue that
secrete saliva and amylase (an enzyme that helps break down
food). There are three salivary glands - the sublingual, submaxillary, and parotid.
Trachea: The trachea is identifiable by its ringed cartilage which provides support.
Larynx: anterior to the trachea. The larynx is the voice box, and it allows rats
to make squeaking noises.
Bronchi: right and left bronchi. The forking of the trachea occurs immediately dorsal to the aorta and cannot be seen at this time. Each bronchus leads to a lung where it branches
further into bronchioles
Diaphragm: muscular wall separating the thoracic and abdominal cavities.
Lungs: four lobes on the right lung and only one on the left lung.
Notice the lungs are located within closed cavities which are lined by membranes called the pleura.
Arteries/Veins: Veins carry used blood back to the heart and lungs.
The lungs re-oxygenate the blood and the heart pumps it back to the rest of the body.
Heart: The heart is encased in the pericardial sac (Pericardium) sends blood throughout the body
Pericardium: encases the heart
Atrium: left and right atrium sit on the top portion of the
heart, receiving chambers for blood
Ventricles: left and right ventricles are found in the bottom
portion. pumps blood to lungs