eChapters

This practical assignment is designed in a way that students will acquire knowledge on various development departments in the district, especially on organizational structure, functioning and activities of any agency like District Rural Development Agency (DRDA).

PURPOSE

To get the students acquainted with the organization and functioning of DRDA.

To give the students a brief idea about the organizational structure and functions of other development departments at district level.

THEORETICAL ORIENTATION

The word “democracy” is derived from the Greek roots - ‘cracy’ meaning ‘rule of and ‘demos’ meaning ‘the people’. It is governance of the people, by the people, for the people. Rule by majority is, no doubt, an important feature of this system of governance; but the more important ingredient is rule by consultation - consultation between the people’s representatives on one hand and consultation with the officers on the other. ‘Decentralization’ means devolution of central authority among local units close to the areas served. Where authority is devolved by this process on people’s institution, it is ‘democratic decentralization’.

At the instance of the Prime Minister it was decided to give the process of the three-tier administration the strictly Indian name, “Panchayati Raj” which means a system of government. Panchayati Raj was conceived system of democratic local self-Government. Earlier, Mahatma Gandhi also advocated panchayati raj as the foundation of India’s political system, as a decentralized form of government in which each village would be responsible for its own affairs. The term for such a vision was Gram Swaraj (“village self-governance”). The institution of Panchayat represented not only the collective will, but also the collective wisdom of the entire rural community.

The Balwant Rai Mehta Committee, headed by M P Balwant Rai Mehta, was a committee appointed by the Government of India in January 1957 to examine the work of the Community Development Programme (1952) and the National Extension Service (1953) and to suggest measures for their better work. The committee recommended the establishment of the scheme of ‘democratic decentralisation’ which finally came to be known as 'Panchayati Raj' which would be a 3-tier system - 'Gram Panchayat' at the village level, Panchayat Samiti at the block level, and Zilla Parishad at the district level.

Teratology : is the study of abnormal development. If the malformation involves an organ or only a portion of the body, it is called an anomaly. If it is so extensive great deformity of the individual occurs when the animal is designated a monster.

etiological basis of teratology : All teratogenic agents directly or indirectly ar;ect the process of cell differentiation. These agents are divided into two broad categories i.e genetic or Intrinsic factors and environmental or extrinsic factors.

Genetic or Intrinsic factors : There are several types of genetic factors that result in abnormal development.

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.

Each optic vesicle grows outwardly until it comes into contact with the surface ectoderm. At this point, the optic vesicle induces the overlying ectoderm to thicken and to invaginate against the optic vesicle. The optic vesicle becomes concave and convert into double walled optic cup. The attachment of optic cup to the brain is called optic stalk. The space between inner and outer walls disappears as they come opposed. Since invagination of optic cup occurs at the ventral margin of the vesicle a groove is formed in ventral rim of the cup which extends along the ventral surface of the optic stalk (choroid fissure) which closes at the end of embryonic period. The groove and the notch in the optic cup are referred to collectively as the optic fissure. The optic fissure begins to close by fusion of its edges soon after the optic cup is completely formed. While it is open, the fissure allows a branch of the choroid artery (Hyaloid artery) into the cavity of the optic cup.

With the development of the optic cup the lens placode invaginates into rim of the optic vesicle and forms lens vesicle. The lens vesicle loses contact with the surface ectoderm and positioned at the opening of the optic cup and forms lens.

Towards the end of the third week of embryological development, the notochord induces the overlying columnar ectodermal cells of the embryonic disc to become pseudostratified neuroepithelial cells and form a spoon shaped thickening of dorsal ectoderm called the neural plate. The cranially expanded region of the neural plate forms the primordium of the brain, while the narrower region caudal to the brain gives rise to spinal cord.

The raised lateral edges of the neural plate form the neural folds while the depressed midline region of the plate forms the neural groove. Cellular proliferation at the medial aspects of the neural folds causes these structures to gradually approach each other in the midline, meet and fuse, forming the neural tube which encloses a central neural canal.

The integumentary system comprises the skin its hair and glands and modified cutaneous structures hooves, claws, horns, beak and feathers. Although the mammary gland is a skin derived organ, because of its close association with the female genital system it is included in respective chapter. The skin consists of two layers: a superficial layer, the epidermis, which is derived from ectoderm and a deeper layer, the dermis, which develops from mesoderm.

Epidermis : The epidermal layer covering the entire embryo initially consists of a single layer of cuboidal cells resting on a basal lamina. Shortly after neurulation, these ectodermally derived cells divide and give rise to a superficial layer of flattened cells, the periderm and underlying layer of cuboidal cells, the basal layer. Further, proliferation of the cells gives rise to an intermediate layer resulting in a multi-layered covering of epidermis. Cells of neural crest and mesodermal origin also contribute to the population of cells found in the skin.

Somites are derived from paraxial mesoderm and they are located lateral to the developing notochord and neural tube. During the third week of gestation in domestic animals, the outlines of somites first become visible and in the fifth week of gestation the somite formation is completed. Somites differentiate into sclerotome, myotome and dermatome. They form skeletal, muscular and dermal elements i.e, vertebral column, muscles and dermis respectively.

The connective tissue, cartilage and bone all differentiate from mesenchyme which arises chiefly from mesodermal somites and lateral layer of somatic mesoderm while connective tissue of alimentary canal and lower respiratory tract is derived from splanchnic mesoderm. Mesenchyme is a spongy meshwork composed of branching cells spaces between which are filled by ground substance. The supporting tissues, connective tissue, cartilage and bone are derivatives of mesenchyme in which ground substance is gelly like, stiff and firm respectively.

Lymph vessels arise from mesoderm by vasculogenesis and angiogenesis in common with the arteries and veins. Initially six primary lymph sacs develop in the late embryonic period. They are paired jugular sacs lateral to the internal jugular veins, a single retroperitoneal sac developing close to the root of the mesentry, the cisterna chyli dorsal to the retroperitoneal sac and a pair of iliac sacs at the junction of the iliac veins.

Lymphatic vessels draining the head, neck and fore limbs arise from jugular sacs. Drainage of lymph from the pelvic region and hind limbs is through the iliac sacs, while the retroperitoneal sac and cisterna chyli drain the viscera. At a later stage of lymphatic development, the lymph sacs become interconnected by a series of lymphatic vessels.The plexus between the jugular sacs and the cisterna chyli gives rise to the thoracic duct which opens into the jugular veins.

lymphatic organs : The lymphatic organs are fully developed and functional before birth. Immunocompetent cells can be detected in most lymphatic organs by the end of the second trimester of gestation.

lymphnodes : The lymphnodes are formed by the partitioning of small lymph vessels or sacs. Therefore, lymphnodes are usually found in related groups or in chains along the course of a lymph vessel. The partitioning is initiated by the ingrowth of mesenchymal processes into the lymph vessel. The mesenchyme forms a network of lymph sinusoids that communicate with the lumen of the lymph vessel. The mesenchyme also forms a reticular fiber frame work that outlines and supports the sinusoidal network. At this time a blood vessel enters the developing lymphnode. The point of entrance establishes the location of the hilus. At the periphery of the node the mesenchyme condenses to form a capsule. The mammalian lymphnodes consists of cortical and medullary regions. The cortical parenchyma contains lymphnodules, while the central medullary region contains anastomosing cords of lymphoid tissue. The structure of the porcine lymphnode differs from other domestic animals in that the lymphnodules are centrally located with the cords at the periphery. The flow of lymph in the porcine lymphnode is in the opposite direction to that in other domestic animals, with lymph entering at the hilus and leaving from the cortex.

Cardiovascular system consists of heart and blood vessels which include both arteries and veins. Blood vessels formation occurs in two stages i.e vasculogenesis and angiogenesis. Splanchnic mesodermal cells lining the yolk sac form clusters, referred to as blood islands. Vasculogenesis, the formation of blood vessels from blood islands of of Pander, commences during the third week of gestation in domestic animals first in yolk sac and later in the allantois.Development of blood vessels involves a complex series of events during which endothelial cells differentiate, proliferate, migrate and become organized into vascular network. Angiogenesis describes budding and sprouting of new vessels from existing vessels. This process a fundamental requirement for embryological development, continues postnatally.

Indifferent stage: Primordia are present for both sexes (gonads and mesonephric and paramesonephric ducts), although genetic sex is determined at fertilization.

Gonads : are structuarally indistinguishable prospective testis and ovaries. The first sign of gonadal development is a swelling called the gonadal ridge on the medial side of the middle part of the mesonephros. It enlarges due to arrival of primary germ cells. Cells of mesonephric tubules invade the ridge to form clusters and besides surround germ cells resulting in gonadal cords.

The primordial germ cells of these gonads arise from the endodermal cells of the yolk sac. These migrate to the gonadal ridge through the dorsal mesentry. Migration of primordial germ cells from the yolk sac endoderm into the gonadal ridges initiates testicular (if SRY gene is present) or ovarian development. The primordial germ cells form the sex cells, called gonadal blastema. The somatic blastema (non-germ cell) forms the other parenchymal elements of the gonads. The germ cells are capable of amoeboid-like movement.

The kidneys develop from the nephrotome (intermediate mesoderm). The series of nephrotomes forms urino-genital ridge which splits up into an lateral nephric and a medial genital ridge, which project into the coelom from the dorsal wall. This is the short segment of mesoderm that connects somite with lateral mesoderm. Three sets of kidneys are formed during embryologic development in vertebrates viz., pronephros, mesonephros, and metanephros. First two sets are temporary structures and third set becomes the kidneys found in the adult.

The development of the upper respiratory system composed of nasal cavities, naso pharynx and larynx is directly related to the development of the face. The nasal cavities are derived from ectoderm while nasopharynx and larynx are endodermal in origin. The lower respiratory system (trachea and lungs) is a derivative of the embryonic pharynx.

The epithelial lining of the lower respiratory system is endodermal in origin, while the surrounding connective tissue and cartilage are mesodermal in origin. The endoderm and underlying mesoderm from the floor of foregut i.e caudal part of pharynx grow caudally in midline and form the laryngo-tracheal groove at about the level of the branchial arches IV -VI from which the larynx and trachea arise. The laryngotracheal tube consists of an inner endodermal lining and an outer layer of splanchnic mesoderm. It grows into underlying mesenchyme. Ingrowths from the sides of the groove at about the level of the branchial arches IV - VI form a pair of ridges that grow towards each other and fuse forming a septum changing the groove into a tube with a blind end caudally. The rostral end opens into the floor of the pharynx. The blind caudal end expands in a bilobed manner into mesenchyme forming bronchial buds the primordia of right and left lungs while the groove is closing.

larynx : A pair of elevations, aryteniod swellings appears on the floor of the pharynx along midline at the level of branchial arch IV. The hypobranchial eminence is just infront of the arytenoid swellings. The depression between the hypobranchial eminence and the arytenoid swellings becomes the lumen of the larynx. The caudal part of the hypobranchial eminence forms the epiglottis. The arytenoid swellings and adjacent branchial arch mesenchyme form the other laryngeal cartilages and musculature. The thyroid cartilage arises from branchial arches III and IV. The other cartilages are derived from mesenchyme of branchial arches IV, V & VI. The intrinsic musculature of larynx is derived mostly from the branchial arch V and VI. With the exeption of the epiglottic cartilage the cartilages and muscles of the larynx are formed by the end of embryonic period.

Alimentary canal : The endoderm is formed by delamination in mammals and birds. This endoderm surrounded by splanchnic mesoderm forms the gut. The endoderm underlying the embryonic disc and serving as a flat roof to the early yolk sac becomes gut endoderm. At 20^th day a rapidly expanding embryonic disc begins to fold into a cylindrical embryo. The gut endoderm also participates as a component layer. Folding first into the head end and then into the hind end of elongating embryo this endoderm necessarily takes the form of the two internal blind tubes. The open end of the each tube where it becomes continuous with the yolk sac is called an intestinal portal while the tubes are named the foregut and hindgut. The caudal end of the hindgut is cloaca. An intermediate region opening ventrally into the yolk sac through the narrower yolk stalk is midgut.

Development of the face includes the development of orbital, nasal and oral regions. Development of face involves five facial primordia during the embryonic period of development. These primordia include the single frontonasal prominence and the paired maxillary and mandibular prominences.

The frontonasal prominence forms two sets of bilateral ectodermal thickenings, the nasal and lens placodes. Frontonasal prominence shows nasal component (of ridges) and a frontal component. A thickned area of ectoderm olfactory/ nasal placode appears at the medial tips of frontonasal prominence.

1.1 Historical background of the Embryology

Embryology is a branch of Anatomy. It is the study of growth and differentiation undergone by an organism in the course of its development from a single fertilized egg cell into a highly complex and independent living being like its parents. It explains how one develops before he is born. Important changes also take place after birth and continue to occur even to adult stage. eg: Replacement of RbC and WbC is a continuous developmental process and reverting to activities seen in prenatal condition is seen in healing of wounds. So the term ‘Developmental Anatomy’ which includes prenatal and postnatal development is preferred over term embryology as Developmental Anatomy, includes prenatal and postnatal development and as the term embryology refers truly prenatal (Intra uterine) development.

Aristotle (384-332/322 BC) proposed two theories regarding origin of life

Land is merely an area of the earth’s surface comprising all physical, chemical and biological environments that influence the land use (FAO ,1976). Land refers not only to soil but also to climate, landforms, hydrology, geology, natural vegetation including fauna and flora. The land use simply means management of a land for specific uses to meet the human needs in all rural, urban and industrial context, whereas the land use plan refers to a coherent set of decisions about the ways to achieve the desired level preferably on economic background. Thus, the land use planning is the systematic evaluation and assessment of a land and associated attributes for the purpose of identifying the best land use options beneficial to landowners or users without degrading the land resources or environment. It includes not only the landowner or users, but also the policy or decision makers as well as economic experts for financial measures from planning stage or logistic planning to execution.

Land cover

Relates to the type of feature present on the surface of the earth e.g., Fields, trees, concrete high ways.

Land use

Relates to the human activity associated with a specific piece of land. The same land would have a land cover consisting of roofs, pavements, grass and trees. The land use in an area is really an intervention by the people over the existing natural eco-environment for satisfying their needs.

Land cover is distinct from land use despite the two terms often being used interchangeably. Land use is a description of how people utilize the land and socio-economic activity - urban and agricultural land uses are two of the most commonly recognised high-level classes of use. At any one point or place, there may be multiple and alternate land uses, the specification of which may have a political dimension.

In recent times, the interpretations cover a wide spectrum of soil uses, both for agricultural and non agricultural (sewage and human waste disposal, high way construction, water and gas supply, recreation, wild life, urban and industrial structures) and many specialized uses. Soil survey if correctly carried out according to scientific principles, can provide the data base for various interpretations. This is because the same soil properties determine the behaviour of a soil for a variety of different uses. For instance, the content of clay, silt and sand, the shrink and swell behaviour, the permeability of soil to water and air, content of calcium carbonate, salts, organic matter, gypsum, soil depth, depth of ground water, hard pan formation, co-efficient of linear extensibility, water holding capacity etc. are examples of such properties that are important to plant growth and these properties also strongly influence non farm uses. Some examples in support are

A hard or petrocalcic horizon or other slowly permeable layer (clay-pan) in a soil restricts the movement of air and water, thus adversely affecting the plant root growth. Such a layer limits the soils suitability for septic tanks and other onsite waste disposal. It also makes a poor sub grade for high way construction.

A soil high in soluble salts is a poor medium for plant growth; it is also corrosive to iron and steel structures, such as pipelines and fences, causing high maintenance and repair costs.

High organic matter content is generally favourable to plant growth, but it is a limitation for road construction.

The strongly gypsiferous soils (gypsum content >10%) are considered unsuitable for arable crop cultivation because of its dissolution under irrigated or even moderate rainfall and making the surfaces uneven through the developments of sink holes. Such soils are unsuitable for irrigation and drainage canal networks and also for construction of roads, bridges etc.

The shrink- swell soils of India (vertisols) because of summer monsoon rains are suitable for growing a “kharif” crop but are very dangerous for construction of roads, air strips, buildings, laying gas, water pipelines which get distorted, develop cracks and lead to sunken floors etc.

Soil Classification

Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.

Soil classification is grouping of objects in orderly and logical manner into classes based on the properties of soils (differentiating characters) for the purpose of studying and identifying them. The soil individuals are grouped into classes of the lower category (soil series) which are grouped into classes of higher categories (soil orders). The lower categories are defined by large number of differentiating characters and higher category by a few differentiating characteristics.

For soil resources, experience has shown that a natural system approach to classification, i.e. grouping soils by their intrinsic property (soil morphology), behaviour, or genesis, results in classes that can be interpreted for many diverse uses. Differing concepts of pedogenesis and differences in the significance of morphological features to various land uses can affect the classification approach. Despite these differences, in a well-constructed system, classification criteria group similar concepts so that interpretations do not vary widely. This is in contrast to a technical system approach to soil classification, where soils are grouped according to their fitness for a specific use and their edaphic characteristics.

Soil survey is essentially a study and mapping of soils in their natural environment. It is the systematic examination, description, classification and mapping of soils of an area.

2.1. History of Soil Survey in India

The original investigations on Indian soils were carried out by Voelcker dates back to 1893 and by Leather to 1898.They classified the soils of the country into four major groups, namely the Indo-Gangetic alluvium, the black cotton soil or regur, red soil and laterite soil. Schokalskaya (1932) has published a soil map of India based on the Russian concept which describes 16 soil groups such as climate,vegetation, soil-forming materials, salinity, alkalinity, swamps and peats (Bhattacharyya et al. 2013). In 1935,Wadia and his co-workers collected a soil map of India with significance on geological formations and classified the soils as red, black (regur), laterite and lateritic soils of Peninsular India and also Indo-Gangetic Plains (IGP) which includes delta, desert, bhabar, terai and alkali soils. Vishwanath and Ukil (1943) published a soil map of India by placing the soils in different climatic zones for the first time. This was prepared by Imperial Agricultural Research Institute, New Delhi, and published in the year 1943. There were 17 kinds of soils identified, viz., deep black soils, black clay soils, black loamy soils, black sandy soils, red sandy soils, brown sandy soils, red and yellow soils, dark reddish brown soils, mixed soils (white and yellow), alluvium (Indus, Gangetic, Brahmaputra), coarse alluvium, soils of swamp lands, calcareous soils, usar soils, kallar soils, coastal alluvium soils and soils of Great Himalayan Ranges.

Soil survey works were started in 1954, in most of the states as a part of their agricultural development programme, and Bihar (Soil Survey and Land use Planning Scheme, Sabour) was pioneer. In 1954, the soil survey work was started under the leadership of Dr. P. P. Jha following the conventional procedures in Bihar (including Jharkhand) to delineate the soil associations based on geology, relief, physical and chemical characteristics of soils for the first time in India by the then Soil Survey Scheme at Sabour (Mishra et al. 2001; Mishra 2015, 2016). Meanwhile, the National Atlas Organization, Kolkata, prepared a soil map of India in 1957 classifying Indian soils into six major groups and 11 broad types. Murthy and Pandey (1983) applied the working principles of the USDA 7^th Approximation in classifying the Indian soils with available data on soil classes and thus used the US system for the first time at great soil group level, which was transformed into a soil map of India on 1:6.3 million scale. Mishra et al. (1994) attempted to propose “Fluvisols” as the 13th Order in USDA Soil Taxonomy for active floodplain soils frequently occurring in different parts of India and elsewhere. Mishra (2015, 2016) proposed a framework of Indian system of soil classification mainly based on land use options.