Autopsy Types and Procedures

Autopsy Basics

• Autopsy originates from a Greek term which means "to see for oneself."

Types of Autopsies

• Clinical autopsies determine the cause of death in hospitals for research or family requests to diagnose diseases or clarify unclear medical diagnoses.
• Forensic autopsies are for legal reasons when "foul play" is suspected to determine the cause and manner of death and identify the deceased, often in suspicious, violent, or sudden deaths.

Roles in an Autopsy

• A Forensic Pathologist (Prosector) is a physician who conducts an autopsy to determine the cause of death.
• A Diener is a morgue assistant who helps the Prosector.
• A Materials Manager organizes and hands dissection instruments.
• A Recorder records measurements and observations and may take photos.

Fetal Pig Dissection as an Autopsy

• Fetal pig anatomy is very similar to human anatomy.
• Following the student guide, the procedure is similar to a human autopsy.
• All organ systems are removed from the body cavity for better observation of the organs and their placement.

General Orientation of the Fetal Pig

• Dorsal refers to the top side or above.
• Ventral refers to the lower side or below.
• Anterior refers to toward the head or front.
• Posterior refers to toward the tail or rear.
• Lateral refers to toward the side.
• Medial refers to toward the midline.
• Proximal refers to near a point of reference.
• Distal refers to away from a point of reference.
• Right: Structures to the right of the dorsal midline
• Left: Structures to the left of the dorsal midline

Key Features to Examine on a Fetal Pig

• Weight and length are key features to examine.
• The amount and color of hair along with any birthmarks or unique markings are important to note.
• Observe the mouth, nostrils, tongue, ears, and eyes.
• Examine the dorsal side and appendages, especially the feet.
• Examine the ventral side and abdomen.
• Mammary papillae (teats) are for lactation (milk production) in mature female mammals.
• The umbilical cord connects the fetus to the placenta, allowing the exchange of nutrients and waste.
• The umbilical vein carries oxygenated blood and nutrients from the placenta to the fetus.
• The umbilical artery carries deoxygenated blood and waste products from the fetus to the placenta.
• The allantoic duct helps the umbilical cord and placenta is involved in the early development of the urinary bladder and the exchange of gases between the embryo and the mother and contributes to development of the umbilical cord and placenta during the first trimester.
• External genitalia refer to the scrotum and urogenital opening for males, or genital papilla for females. They are sex, or reproductive, organs visible on the outside of the body; also called genitals
• The scrotum is a sac-like structure that contains the testes in males, providing a cooler environment for sperm production.
• The urogenital opening in males is the external opening through which both urine and reproductive fluids (sperm) are expelled.
• A genital papilla is a small projection near the urogenital opening in females.

Incision Procedure

• A Y-shaped incision is made to open the pig.
• The chest plate is removed to expose the heart, lungs, and liver.
• Organs of the trunk are removed as a block for examination.

Respiratory System

• The larynx, or voice box, contains vocal cords for sound production.
• The trachea is a cartilage-lined airway that carries air from the larynx to the lungs.
• Bronchi are two branches of the trachea that direct air into the lungs.
• Lungs are organs where gas exchange occurs, taking in oxygen and releasing carbon dioxide.
• The esophagus is a muscular tube that transports food from the mouth to the stomach.
• The thymus is an endocrine gland that plays a role in the immune system, particularly in infancy.
• The thyroid is an endocrine gland that produces hormones like thyroxine, which regulates metabolic rates.
• The diaphragm is a muscle that separates the chest cavity from the abdominal cavity and is essential for breathing, moving down when inhaling and up when exhaling.
• Histology of Mammal Lung section.

Circulatory System

• The heart includes several key structures.
• The pericardial sac: A fluid-filled membrane that surrounds and protects the heart.
• The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation.
• The coronary artery supplies oxygenated blood to the heart muscle.
• The coronary vein drains deoxygenated blood from the heart muscle.
• The anterior vena cava returns deoxygenated blood from the anterior part of the body to the right atrium of the heart.
• The posterior vena cava returns deoxygenated blood from the posterior part of the body to the right atrium of the heart.
• The pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart.
• The aorta is the largest artery, carrying oxygenated blood from the left ventricle to the rest of the body.
• The left and right auricles are external, ear-like flaps on the atria of the heart.
• The left and right ventricles: Lower chambers of the heart that pump blood out. The left ventricle pumps oxygenated blood to the body, and the right ventricle pumps deoxygenated blood to the lungs.
• Valves: tricuspid, pulmonary, mitral (bicuspid), and aortic
• Interatrial septum: The wall that separates the left and right atria of the heart.
• Foramen ovale (hole in septum): A hole in the interatrial septum in fetal mammals that allows blood to bypass pulmonary circulation; it closes after birth.
• Histology of Mammal Artery and Vein
• Artery: Ring of smooth muscle that lines the wall and helps maintain blood pressure (blood vessel that carries oxygenated blood away to the body)
• Vein: Small amount of smooth muscle that expands, with one-way valves to prevent backflow. (blood vessels that carries deoxygenated blood to the heart)

Digestive System

• The liver produces bile, detoxifies blood, and stores glycogen and vitamins.
• The gallbladder stores and concentrates bile, which emulsifies fats.
• The stomach stores food, mixes it with gastric juices, and begins the digestion of proteins.
  • The cardiac sphincter controls the passage of food from the esophagus into the stomach.
  • Rugae are folds in the stomach lining that allow the stomach to expand.
• Gastric glands produce pepsinogen and hydrochloric acid for protein digestion.
  • Histology of Fundic Stomach:
    • Parietal cells produce hydrochloric acid
    • Chief cells produce pepsinogen
• The pancreas is both an endocrine and exocrine gland that produces pancreatic juice and hormones like insulin, glucagon, and somatostatin, which regulate blood sugar.
• The small intestine is the primary site for digestion and absorption of nutrients and water.
  • Three sections: duodenum, jejunum, and ileum
• The ileocecal valve controls the passage of material from the small to the large intestine.
• The caecum (in large intestine) is a large pouch-like structure of the large intestine that aids in the digestion of plant material (cellulose).
• The large intestine (colon) absorbs water and electrolytes from remaining digested material, forming feces.
  • Parts: spiral (sigmoid) colon, ascending colon, descending colon, rectum, and anus.
• Histology of small and large intestine
  • Villi and microvilli: Folding structures that provide a large surface for absorption

Urogenital System

• Kidneys filter blood and produce urine to remove waste products.
  • Regions: cortex, medulla, and renal pelvis
• Histology of Mammal Kidney - Glomeruli and Bowman’s capsules are filtering units of the nephrons responsible for filtering blood and producing urine
• Ureters are tubes that carry urine from the kidneys to the urinary bladder.
• The urinary bladder stores urine until it is eliminated from the body.
• The urethra is the tube through which urine is discharged from the bladder.
• Female:
  • Ovaries are female reproductive organs that produce eggs and female sex hormones (estrogen and progesterone).
  • Oviducts are tubes that transport eggs from the ovaries to the uterus.
  • The uterine horns are extensions of the uterus in pigs that accommodate multiple fetuses during pregnancy.
  • The uterus is the organ in female mammals where the fertilized egg implants and develops.
  • Histology of Mammal Graafian Follicles: Spherical cell in the ovary that contains an ovum, which can be released during ovulation.
  • The Vagina is the female reproductive canal.
  • The urogenital sinus is a cavity in female mammals into which urine from the urethra empties and then is discharged through the urogenital orifice.
• Male:
  • Testes are male reproductive organs that produce sperm and testosterone.
  • The scrotum is a sac-like structure that contains the testes, providing a cooler environment for sperm production.
  • The epididymis is a coiled structure that stores sperm and transports it to the vas deferens.
  • The vas deferens is a duct that carries sperm from the epididymis to the urethra.
  • Histology of Mammal Epididymis: Note the large population of sperm composed of a head (nucleus) and a flagellum.
  • Seminal vesicles are glands that contribute fluids to semen.
  • The prostate gland is a gland that contributes fluid to semen.
  • Bulbourethral glands are glands that produce alkaline fluid that protects sperm by neutralizing the acidity of the urethra.
  • The penis is the male organ for copulation and urination.

Heart and Kidney Comparisons

• Compare fetal pig heart and kidney with adult pig heart and kidney (both external and internal features).
• Heart: The fetal pig heart has special structures like the foramen ovale, a hole between the right and left atria that allows blood to bypass the lungs, and the ductus arteriosus, a vessel that connects the pulmonary artery directly to the aorta.
  • In an adult pig heart, these structures close after birth, becoming the fossa ovalis and ligamentum arteriosum, since the lungs now supply oxygen.
  • The fetal pig heart is smaller and has thinner ventricular walls compared to the adult pig heart, which has thicker walls, especially in the left ventricle, to support stronger circulation throughout the body
• Kidney: The fetal pig kidney is smaller and still developing, so its structures are not as fully formed or efficient as in the adult kidney.
  • In fetal pigs, the kidneys play a limited role in filtering waste because waste removal is mainly handled by the placenta, not the kidneys.
  • The adult pig kidney is fully developed, larger in size, and performs all functions of waste removal and fluid regulation on its own.
  • Additionally, the nephrons in an adult kidney are more mature and effective at filtering blood compared to those in a fetal kidney

Final Steps

• Organs are placed back into the body cavity.
• The incision is sutured.
• An autopsy report is completed.
• Specimens are disposed of properly.