Structure of a typical long bone

Comments

Post a Comment

Popular posts from this blog

Biodiversity Explanation and Biodiversity in India

  Biodiversity   Our planet, earth, is occupied by diverse kinds of living organisms. They live in various environments. The world is estimated to have 5 to 30 million species of living organisms. At present about 2.5 million species of living organisms have been given scientific names. Over 1.5 million of them are animal species and out of which 750,000 belong to insect species alone. There are 350,000 species of plants including algae, fungi, mosses and higher forms of plants. Thus the existence of different forms of a species or genus and diverse adaptations for, varied surroundings are referred to as 'biodiversity'.   The survival of such a vast range of living beings could be ensured only when their habitats and environmental conditions remain without alterations. The term '  biosphere ' had been coined to highlight the interdependence of living and non-living world. It represents a stable environment of various physical and biological factors which have been op...
Read more

Endoplasmic Reticulum (ER) and Function of Endoplasmic Reticulum

  Endoplasmic Reticulum. (ER)   Electron microscopic study of sectioned cells has revealed the pres-ence of a three dimensional network of sac-like and tubular cavities called cisternae  bounded by a unit membrane inside the cell. Since these structures   are concentrated in the endoplasmic portion of the cytoplasm, the entire organisation is called the  endoplasmic reticulum . This name was coined by  Porter  in 1953.   The occurrence of ER varies from cell to cell. They are absent in erythrocytes, egg cells and embryonic cells.   The ER is the site of specific enzyme controlled biochemical reactions. Its outer surface carries numerous ribosomes. The presence of ribosomes gives a granular appearance . In this condition ER is described as  rough endoplasmic reticulum  (RER). RER is the site of syn-thesis of proteins. Ribosomes are absent on  smooth endoplasmic reticulum  (SER). SER is concerned with lipid metabolism. ...
Read more

Developmental Biology - Gametogenesis, Spermatogenesis, Oogenesis, Fertilization

  Developmental Biology   The process of sexual reproduction ensures the formation of a diploid zygote which could constitute the next generation. A zygote is a single celled structure. By an ontogenetic process the zygote undergoes various develop-mental phases resulting in multicellular embryonic organisation. These phases include  cleavage ,  gastrulation , neurulation ,  organogenesis  and the pe-riod of  growth  and  histological differentiation . Inspite of the fact that or-ganisms vary in their structure, form and mode of life, the processes of embryogenesis, development and differention are remarakably similar in all metazoans. Till later stages of development a fundamental uniform pattern in development can be observed. The ontogenetic stages also reflect the historical development of species or  phylogenetic development .   Realising the mode of formation of a young individual of the next gen-eration has always interested ...
Read more