eChapters

The sense organs are the organs of the body that respond to external stimuli by conveying impulses to the nervous system. The sense organs allow animals to sense changes in the environment around them and in their bodies so that they can respond properly. Animals can sense a wide range of stimuli that include the sense of vision, the sense of hearing, the sense of olfaction (smell), the sense of taste and the sense of touch including pain and pressure. In animals, there are two major groups of senses, the general senses and the special senses.

The defined endocrine glands include the pituitary gland, the pineal gland, the adrenal glands, the thyroid gland and the parathyroid glands. The organs which contain groups of endocrine cells include the pancreas, the testis, ovary and placenta. The Hassall's corpuscles of thymus secrete hormone which contributes to the maturation of T-lymphocytes. Hence the thymus can be considered as having an endocrine function.

Pituitary : Refer to Part II, Chapter 2

Thyroid gland : Refer to Part II, Chapter 2

Pineal gland (Epiphysis cerebri) : Develops as a dorsal neuro epithelial diverticulum of the caudal part of the roof of the diencephalon. After its formation the gland remains attached to the diencephalon by a stalk. The neuroepithelial cells differentiate into pinealocytes and glial cells. The developing gland is surrounded by a thin layer of piamater.

Heart

The heart is a cone shaped thick walled and four chambered muscular organ. It lies obliquely craniocaudal in the middle mediastinum in between the left and right lungs and is covered by pericardium inside the thoracic cavity. The major part of heart (about 60 per cent) lies to the left of the middle mediastinum. The broad upper end is the base of the heart. It lies at the junction of the dorsal and middle third of the dorsoventral diameter of thorax at the level of about third to sixth rib and it faces craniodorsally. The narrow lower end is the apex. It lies just dorsal to the sternum at the level of about sixth rib and it faces caudoventrally. The surfaces, right and left are convex. They meet cranially at the right ventricular border and caudally at the left ventricular border. The right (cranial) border is strongly convex. It runs ventrally and caudally. The greater part of this border lies parallel to the sternum. The left (caudal) border is much shorter and nearly vertical. The surfaces of the heart are marked by grooves which indicate the division of the heart into four chambers the two atria dorsally and the two ventricles ventrally. The atria are separated internally by the interatrial septum. The ventricles are separated by interventricular septum. The circular coronary groove indicates the division of the heart in to atria dorsally and ventricles ventrally. It encircles the heart in its upper third part except at the level of the origin of pulmonary artery. The coronary groove is quite deep and wide. It provides passage for the coronary artery and vein. Apart from these, it is deeply filled with fat. The right (subsinuosal) interventricular groove and left (paraconal) interventricular groove indicates the line of separation between the two (right and left) ventricles by the interventricular septum. Both of these grooves run downward from the coronary groove towards the apex parallel to the respective borders and terminate just above the apex. The right and left ventricular grooves are occupied by the respective coronary vessels along with the fat.

The great vessels that leave and enter the chambers of the heart include the Aorta, the Pulmonary Artery and the Pulmonary Veins.

Aorta

The Aorta is the main systemic arterial trunk. It begins as ascending aorta at the base of the left ventricle, passes craniad and dorsad between the pulmonary artery on the left and the right atrium on the right and then turns caudad inclining slightly to the left, thus describing a curve called the aortic arch with its convexity directed upward and forward and the concavity facing downward and backward. From here it proceeds caudad on the ventrolateral surface of the thoracic vertebrae and the longus colli muscle as the descending aorta. At its origin from the base of left ventricle, the caliber of the aorta is greatest forming the bulbus aorta and here it presents three dilatations called the aortic sinuses. As the descending aorta reaches the level of the seventh thoracic vertebra it continues behind as thoracic aorta running through the middle and caudal mediastinum between the left and right lungs. The thoracic aorta first lies to the left of the median plane and then gradually inclines inwards medially and becomes median in position when it reaches to the diaphragm. It then passes through the hiatus aorticus of the diaphragm and enter the abdominal cavity as abdominal aorta. From here it passes caudad below the bodies of the lumbar vertebrae and the psoas major muscle. After reaching at the level of the sixth lumbar vertebra, the abdominal aorta terminates in the iliac quadrification by dividing into two external and two internal iliac arteries.

The lymphatic system is a part of circulatory system and a vital part of the body’s immune system. It is comprised of lymph vessels, lymph ducts, and lymph nodes that move the lymph from tissues to the blood stream and the organs such as the spleen, thymus and bone marrow that produce the lymphocytes and white blood cells. Lymph is very similar to blood plasma. During circulation through the body, the blood reaches to the capillaries at the interstitial spaces. The plasma of the blood is filtered through the capillary wall. The fresh oxygen along with nutrients, hormones and other necessary fluid matters from this plasma are released in to the interstitial fluid and about 85 per cent of the plasma along with the carbon dioxide and metabolic wastes, return into the circulation through the capillary walls. The remaining 15 per cent of the plasma along with the debris of other waste products and the lymphocytes constitutes the lymph which is returned to the circulation through an accessory route of lymphatic vessels and lymph nodes constituting the lymphatic system.

Lymph Vessels: The lymph vessels start as finger-like blind ending thin walled lymph capillaries in the interstitial connective tissue. These capillaries form a network and drain into the thicker walled collecting lymph vessels, lymph ducts and lymphatic trunks. Finally the larger lymph trunks and ducts empty their content the lymph into the cranial vena cava at the thoracic inlet. The lymph vessels contain numerous valves with one or two leaflets preventing the back flow of lymph through the lymph vessels. During its course in a centripetal direction through the lymph vessel, the lymph of each lymph vessel has to pass through at least one lymph node prior to its entry into the blood circulation. As a result there lies a chain of lymph nodes on the pathway of lymph vessels in the body.

Most of the bones of the skull are joined (articulated) with the adjacent bones by sutures. These are immovable joints (synarthroses). The uniting medium is a fibrous tissue and is called the sutural ligament. Most of these joints exist in the early life of the animals and as the age of the animal advances the adjacent bones fuse with each other.

In the realm of cell culture, the quality and composition of the growth media and reagents play a pivotal role in growth and sustaining cells in vitro. The preparation of these essential components requires precision, attention to detail, and adherence to the strict protocols to ensure optimal cellular growth, viability, and experimental reproducibility. This introduction serves as a foundational overview of the critical aspects involved in the preparation of media and reagents for cell culture experiments. Furthermore, the preparation of media and reagents for cell culture necessitates adherence to stringent quality control measures to ensure consistency and reproducibility across experiments. Validation of media batches, sterility testing, and periodic quality assessments are essential practic

Introduction

Structural changes in host cells by the viral infection is referred as cytopathic effect (CPE) and the responsible virus is called cytopathogenic virus. As a virus hijacks a cell to make copies of itself, the cell goes through distinct changes in its chemistry and structure. These effects are easiest to see in lab grown cell cultures. The severity of the damage caused by the virus depends on the specific virus itself, the type of cell it infects, how many viruses infect each cell (MOI), and other factors.

The early stages of this damage, called cytopathic effects (CPE), can be spotted directly under a microscope without any dyes or special treatments. While various types of CPE exist in living cells, some signs of viral infection, like inclusion bodies, require staining the cells to be visible. We can classify viruses based on how quickly they cause visible damage (cytopathic effect) in cell cultures. Viruses are typically considered slow if it takes 4-5 days to see this effect in cultures with a low starting dose of virus (MOI). On the other hand, viruses are considered fast if the damage shows up in just 1-2 days under the same conditions. It is important to note that at a high MOI all CPE can occur rapidly. So all decisions about rate of CPE appearance should be based on the lowest MOI that produces CPE

Muscles of the back (spine), muscles of thorax and muscles of thoracic girdle of Horse, Dog, Sheep and Goat, and Pig almost resemble those of ox except for a few miner differences due to variations in the number of bony segments of the vertebrae, ribs and sternebrae.

Fowl

Muscles of back (spine)

Spinalis thoracis is the thoracic part of the spinales complexus. It originates by aponeurosis on the spinous processes of the thoracic vertebrae including the dorsal median ridge of the synsacrum, dorsal surface of the bases of the transverse processes and the cranial border of the ilium. The muscle inserts by multiple tendinous slips on the spinous processes, vertebral arches, transverse processes of several thoracic vertebrae and the vertebral ribs. This muscle helps in straightening of the head and neck of the fowl.

Iliocostalis et longissimus dorsi is the segmented muscle originating on the transverse processes of the thoracic vertebrae and inserting on the vertebral parts of the ribs. This muscle assists in elevating the thorax.

Boundaries

The cavity of thorax (thoracic cavity) is formed like a truncated cone which is compressed laterally in its cranial part and some what wider in its caudal part. The dorsal wall or roof of the thorax is formed by the thoracic vertebrae and the ligaments and muscles connected with them. The lateral walls are formed by the ribs and intercostal muscles and other muscles supporting the walls internally and externally. The floor or the ventral wall is formed by the sternum and costal cartilages along with the ligaments and muscles attached to them. The caudal wall or the base of the thorax is formed by the diaphragm. It slopes craniad and ventrad. It is bound dorsally by the last thoracic vertebra, ventrally by xiphoid cartilage and laterally by the last pair of ribs and the costal arch formed by the union of costal cartilages of asternal ribs. The apex of the cone is narrow, nearly oval or triangular in form and it is directed cranially. The cavity of the apex is bound dorsally by the first thoracic vertebra, laterally by the first pair of ribs and ventrally by the first sternebra along with manubrium sterni. The apex is fully occupied by the longus colli muscle, oesophagus, trachea, vessels, nerves and lymph nodes. The width of the thorax is greatest at the level of ninth ribs. The wall of the thorax is internally lined by the serous membrane which is a part of the pleura.

The venous drainage from the wall of the thorax is performed by the dorsal intercostal veins. These veins are distributed as below.

The dorsal intercostal veins are twelve pairs in number. Of these, the fourth to twelfth intercostal veins from right side and fifth to twelfth intercostal veins from the left side join the vena azygos.

The thoracic spinal nerves of the horse, dog, sheep and goat, pig and fowl almost resemble to those of ox in origin, disposition and distribution. The number of pairs of thoracic spinal nerves, however, vary and it corresponds to the number of thoracic vertebrae present in those particular species of animal.

Surface locations for clinical examination on the wall of thorax

Lymph nodes

Prescapular lymph node is palpable as a cylindrical object just cranial to the point of shoulder. Palpation can be performed by putting the base of the hand on the cranial edge of the scapula and pressing forward with fingers. This enables to roll the skin and feel the lymph node flicking underneath the fingers.

Heart

The clinical examination of heart is performed by percussion and auscultation on the thoracic wall.

For percussion of heart, usually the fifth rib is identified opposite the olecranon of a straight vertical limb. Two fields are identified for percussion of heart. (1) The area of absolute cardiac dullness corresponds to the area of contact of the pericardium with the thoracic wall. It gives a flat sound on light percussion. (2) The area of relative cardiac dullness indicates the outline of heart which is covered by the thin margin of lung. It needs somewhat stronger percussion to define this area which is usually difficult in animals. The absolute dullness is used to test the hypertrophy, displacement and pericardial effusion. In ox, the normal area of absolute dullness is explored in the fourth and fifth intercostal spaces. Traumatic pericarditis may result in absolute dullness in these spaces extending above a horizontal line through the shoulder joint. In horse this area is a triangle bounded by the triceps in front, the sternum below and the lung along the line joining these two. On left side of the normal horse, the dullness extends about 7 cm above the olecranon in the fourth intercostal space and about 3 cm above the olecranon in the fifth space. On the right side, the dullness extends about 3 cm above the olecranon in the fifth space only. In dog, the area of absolute dullness extends about 1 to 2 cm above the sternum in the fourth and fifth intercostal spaces in the line with the corresponding costochondral junction.

Horse

In addition to the common articulations of vertebrae, the lumbar region of horse has two special articulations, the inter-transverse articulations and lumbosacral articulations.

The intertransverse articulations are bilateral joints formed between the transverse processes of the fourth and fifth and between the fifth and sixth lumbar vertebrae. The articular surfaces of these joints are the oval facets on the transverse processes of these vertebrae, the cranial ones being concave while the caudal ones the convex. These are synovial joints (diarthrodial). The capsule of the joint is reinforced ventrally.

The lumbosacral articulations are diarthrodial joints formed between the transverse processes of the sixth lumbar vertebra and the wings of the sacrum. These joints are similar to the intertransverse articulations.

The sacroiliac articulation of the pelvis is similar to that of ox. However, the sacrosciatic ligament is broader. Its lateral surface is related to middle gluteus, biceps femoris and semitendinosus muscles.

Bar chart: The bar chart or diagram is one of the ways of graphically displaying categorical data. A bar chart is identical to a histogram, except that in a bar chart the rectangles representing the various frequencies are spaced, thus indicating that the data is categorical. The bar diagram is used for variables measured on nominal or ordinal scales.

General article: A general or popular article is like a short review paper based on an area of public interest. The author can incorporate his own idea on the particular topic in this article.

Halo effect: When making an observation, some observers may be influenced to rate an individual on one aspect of the interaction by the way he was rated on another. This is similar to something that can happen in teaching when a teacher’s assessment of the performance of a student in one subject may influence his rating of that student’s performance in another.

Judgment sampling: Judgment sampling is utilized frequently during qualitative research to develop hypotheses rather than to generalize to larger populations. The research worker’s decision is used for selecting items which are considered as representative of the population in judgment sampling.

Karl Pearson’s coefficient: Karl Pearson’s coefficient of correlation (also simple correlation) is the most widely used methods of measuring the degree of relationship between two variables. This coefficient assumes that there is a linear relationship between the two variables; the two variables are causally related which means that one of the variables is independent and the other one is dependent; and a large number of independent causes are operating in both variables so as to produce a normal distribution.

Latent Structure Analysis: Latent Structure Analysis shares both of the objectives of factor analysis to extract latent factors as well as an express relationship of observed (manifest) variables with the factors as their indicators and to classify a population of respondents into guanine types. This analysis is suitable if the variables involved in the study do not possess dependency relationship and happen to be non-metric.