Experiments on the appearance and anatomy of the domestic pigeon (or domestic chicken)
Experiments on the appearance and anatomy of the domestic pigeon (or domestic chicken)
Source of content: general zoology lab guide.
Operation method
Experiments on the appearance and anatomy of the domestic pigeon (or domestic chicken)
Principle
1. to recognize the basic structure of the systems of birds and their main features adapted to the flying life through the observation of the shape, skeleton and anatomical structure of the domestic pigeon (or domestic chicken); 2. to learn the methods of dissecting birds.
Materials and Instruments
Specimens Live homing pigeons Move I. Observations on the skeletal system of the domestic pigeon (or domestic chicken) Caveat 1. This lab focuses on anatomical manipulation. 2. The skeletal system is based on the understanding of the general structure of birds related to the adaptation to the flying life, and the memorization of the number and names of localized bone fragments, such as the skull, is not required. Common Problems I. Demonstrations 1. demonstration of orthotropic, downy and hairy feathers of birds. For more product details, please visit Aladdin Scientific website.
Bell shaped hood Ether Dissection tray Bone scissors Scissors Tweezers
1. Spine
Distinguish between the cervical, thoracic, lumbar, recommendatory and caudal vertebrae. With the exception of the cervical and caudal vertebrae, most of the vertebrae in birds have healed together, making their backs stronger and easier to fly.
(1) Cervical vertebrae
14 (16 - 17 in domestic chickens), separated from each other. The first and second cervical vertebrae are specialized into atlas and cardinal vertebrae. Take a single cervical vertebrae (except atlantoaxial and cardinal vertebrae) and observe the articulating surfaces between the vertebrae; what is the difference between the upper and lateral surfaces? What is the shape of the cervical vertebrae in birds? What are their functions?
(2) Thoracic vertebrae
The 5 thoracic vertebrae are fused to each other, and each thoracic vertebra is associated with a pair of ribs. What is the difference between the ribs of birds and those of fish?
(3) The healing sacrum (healed sacrum)
It is formed by the healing of thoracic (1), lumbar (5-6), sacrum (2), and caudal (5) vertebrae.
(4) Caudal Vertebra
There are 6 relatively separate caudal vertebrae behind the healed sacrum.
(5) Caudal vertebrae
Located at the end of the spine, it is formed by the healing of 4 caudal vertebrae.
2. Skull
The bones of the bird's head are made up of thin, lightweight bone fragments that are almost seamless (the boundaries of the fragments are recognizable only in young birds).
The anterior part of the skull is the facial region; the posterior part is the parieto-occipital region, with the large occipital foramen on the posterior ventral surface. The skull has large, deep orbits centrally on both sides.
Small auricular foramina posterior to the orbits. Note that the maxilla and mandible extend forward to form a rostrum and are not dentate.
3. Shoulder girdle, forelimbs and sternum
(1) Shoulder girdle
Consists of scapula, olecranon and clavicle, very robust, divided into right and left parts, connected ventrally to the sternum.
A scapula: slender, blade-like, located dorsal to the thorax, parallel to the spine.
B Ulna: stout, on the ventral side of the scapula, connected to the sternum.
C clavicle: elongated, before the rostrum, the right and left clavicles are fused ventrally to form a "V"-shaped fork. In life, the upper end is connected to the rostrum, and the lower end is connected to the sternum by a ligament. The foramen is unique to birds. What is its function?
D Acromion: a joint depression formed by the scapula and olecranon, associated with the humerus.
(2) Forelimbs
Recognize the shape and structure of the bones of the humerus, ulna, radius, and carpal bones against the diagrams in the textbook, and note the characteristics of their carpometacarpal merger and phalangeal degeneration.
(3) Sternum
It is a broad bone piece in the middle of the front of the trunk, the left and right edges are connected with the ribs, and there is a longitudinal keel protrusion in the center of the abdomen.
4. Girdle and hind limbs
(1) Girdle
The ilium, pubis, and sciatica that make up the girdle are fused into an anonymous bone.
The ilium forms the anterior part of the anulus and the sciatica forms its posterior part.
The pubis is elongated and lies at the ventral margin of the sciatic bone. Open pelvis.
(2) Hind limbs
Compare the diagram in the textbook and note that the tibia and tarsus merge to form the tibiotarsus.
The tarsus and metatarsus merge to form the tarsometatarsus. The joint between the two bones is the intertarsal joint. Note the arrangement of the phalanges.
Internal anatomy of pigeon (or chicken)
20-30 min before the experiment, put the domestic pigeon (or domestic chicken) into a bell-shaped mask filled with ether to anesthetize it to death. Alternatively, the dorsal part of the experimental animal is pinched tightly to asphyxiate it to death.
Before dissecting the specimens, the specimens were first observed for appearance. The domestic pigeon (or domestic chicken) has a fusiform body. The whole body is divided into five parts: head, neck, trunk, tail and appendages. The whole body is covered with feathers, except for the beak and tarsal-plantar area, which has a horny covering. The head has a beak at the front (the skin at the base of the upper beak is called the wax membrane). There is an external nostril on each side of the base of the upper beak. Eyes with movable eyelids and translucent transient membranes. Postocular aperture covered by feathers behind the eye. Forelimbs specialized into wings. Count the number of primary and secondary flight feathers on the wings. On the dorsal surface of the tail there is a caudal fat gland, what is its function?
Wet the ventral feathers of the experimental bird with water and pluck them. Be especially careful when plucking feathers from the neck, not more than 2 or 3 at a time, and in the direction of the feathers. Hold the thin skin of the neck with your hand while plucking to avoid tearing the skin. Place the plucked bird in a dissecting dish. Note the distribution of the feathers and distinguish between feathered and naked areas. What does this mean for flight?
Incise the skin along the keel protuberance. The incision is made anteriorly to the base of the beak and posteriorly to the cloaca. Separate the skin with the blunt end of a scalpel; be especially careful when peeling to the crop to avoid breakage.
Carefully incise the pectoralis major muscle along the sides of the keel and along the edge of the forks. Leave the muscle at the stop of the upper end of the humerus, the muscle exposed below being the pectoralis minor. Cut it in the same way and try to draw these muscles to understand their function. Then cut the ribs with bone scissors along where the sternum joins the ribs, and cut the olecranon with bone scissors where it joins the forks. Remove the sternum and the olecranon, etc., and the natural position of the internal organs can be seen.
1. Digestive system
(1) Alimentary canal
Mouth: cut the corners of the mouth for observation. The margins of the upper and lower jaws bear horny rostrums. The tongue is situated in the mouth with an arrow-shaped anterior end. At the top of the mouth there is the endonasal aperture in the middle of two longitudinally traveled mucosal fold walls. The posterior part of the mouth is the pharynx.
Esophagus: It runs down the left side of the ventral surface of the neck and expands into a crop at the base of the neck. The crop stores food and partially softens it.
Stomach: The stomach consists of a glandular stomach and a muscular stomach. The glandular stomach, also known as the foregut, is connected to the crop at the upper end and is long fusiform. Cut open the glandular stomach and observe the rich digestive glands on the inner wall. The muscular stomach, also known as the sand bladder, is connected to the foregut at the upper end and is located at the posterior edge of the right lobe of the liver, and is a flat circular muscular sac. The myogastric stomach was dissected, and the muscle fibers arranged in a radial pattern were examined. Myogastric stomach wall is thick and hard, and the inner wall is covered with hard keratin membrane, which is yellowish green. Myogastric stomach contains sand particles, which are used to grind food.
Duodenum: Located at the junction of the glandular and muscular stomachs, it has a U-shaped curve (within the mesentery of this curve, the pancreas is lodged). Look for the population of the bile ducts and pancreatic ducts.
Small intestine: elongated, coiled in the abdominal cavity and finally connected to the short rectum.
Rectum (large intestine): short and straight, opening at the end into the cloaca. At its junction with the small intestine, there is 1 pair of bean-shaped cecums. The large intestine of birds is shorter and cannot store feces.
(2) Digestive glands: How many lobes are there in the liver of the pigeon (or chicken)? Note that the domestic pigeon does not have a gall bladder. On the back of the right lobe of the liver there is a deep depression from which two bile ducts extend into the duodenum.
2. Respiratory system
External nostrils: openings at the base of the upper rostrum (located anteriorly and inferiorly to the wax membrane in the domestic pigeon).
Inner nostril: located in the longitudinal groove in the center of the roof of the mouth.
Larynx: located behind the root of the tongue, the central longitudinal fissure is the laryngeal valve.
Trachea: generally as long as the neck, supported by a complete ring of cartilage. At the bifurcation of the right and left trachea there is a more expanded song tube, which is the characteristic vocal organ of birds.
Lungs: left and right 2 lobes. Located in the dorsal aspect of the thoracic cavity, they are 1 pair of solid spongy organs with less elasticity.
Air sacs: pairs of membranous sacs connected to the lungs, located in the neck, thorax, abdomen and inside the skeleton (see demonstration specimen).
3. Circulatory system
(1) Heart
The heart is located in the midline of the body and is very large. The pericardium is pulled up with forceps and then cut longitudinally with small scissors.
Removing the pericardium from the dorsal and lateral sides of the heart reveals that the heart is separated into anterior and posterior parts by a band of fat. The maroon enlarged portion in front is the atrium, and the lighter colored portion behind is the ventricle.
(2) Artery
Near the base of the heart, the remaining pericardium, connective tissue, and fat are cleared away, exposing two larger grayish-white vessels, the innominate arteries.
The innominate artery divides into the carotid, subclavian, brachial, and thoracic arteries, which enter the neck, forelimbs, and chest, respectively (the subclavian artery is a direct continuation of the innominate artery).
By gently lifting the right innominate artery with forceps and pulling the heart slightly downward, the right body arterial arch is seen to go dorsal posteriorly, transforming into the dorsal aorta posteriorly, giving off many vessels along the way to the organs in question. Lifting the right and left atrial atrial arteries slightly, the pulmonary arteries below are seen to divide into 2 branches and then go around to the dorsal side and reach the lungs.
(3) Veins
In front of the right and left atria, two thick and short vein trunks can be seen, which are the anterior large veins. The anterior large veins are formed by the confluence of the jugular, brachial, and thoracic veins. These veins are almost parallel to the artery of the same name and are therefore easily visible.
Turning the heart to the front, a thick vessel is seen leading from the anterior margin of the right lobe of the liver to the right atrium; this is the posterior great vein.
From experimental observation it is seen that the heart of the bird is very large and differentiated into four chambers; the venous sinuses are degenerated; and the body arterial arch is left with only one branch on the right side. Thus the arterial and venous blood are completely separated, and a perfect double circulation is established. Consider how the above features relate to the flying lifestyle of birds.
4. Genito-urinary system
(1) Excretory system
Kidneys: purple-brown, right and left pairs, each divided into three lobes, close to the dorsal wall of the body cavity.
Ureter: runs down the ventral surface of the body cavity and passes into the cloaca. Birds do not have a bladder.
Cloaca: cut open the cloaca, you can see the cavity with 2 transverse folds, the cloaca is divided into 3 chambers: the front of the larger for the fecal tract, the rectum that opens here; the middle of the cloacal tract, the vas deferens (or fallopian tubes) and the ureter opens here; and finally for the anal tract.
(2) Reproductive system (students can exchange male and female specimens for observation)
Male: with paired white testes. The vas deferens extends from the testes and enters the cloaca parallel to the ureter. Most birds do not have external genitalia.
Female: right ovary reduced; left ovary filled with follicles; well-developed oviduct. The anterior end of the oviduct passes through the body cavity by means of a trumpet; the inner wall of the posterior curvature is rich in glands that secrete proteins and form the egg shell; the end is short and wide and opens into the cloaca.