embryonic development of a frog

Comparative Embryology - Haeckel (1834-1919) formulated that 'ontogeny recapitulates phylogeny'. This means that the developmental stages that an organism goes through repeat the evolutionary history of the group to which the organism belongs. Stages in Embryological Development Though it..

In the life of most flowering plants, 3 distinct phases are seen. i) Seed germination and vegetative growth phase ii) Reproductive phase iii) Senescence and dea..

Growth period in man may be divided into 5 stages. Prenatal stage - 9 months of embryonic life Infantile stage - Birth to 10 months of age Early childhood - 10 months to 5 years of age Juvenile stage - 5 years to 14 years or the time of puberty Adolescent and post adolescent stage - 14 ye..

a) In honey bees (Apis indica) larvae are fed by the workers and the development depends on nature of food provided to the larvae. b) In birds like sparrow, weaver bird, pigeon etc. the hatchlings are naked, blind and need more parental care. Such young ones are called altricial or nidico..

. The first half of the phase and the changes in these phases are controlled by estrogens and progesterone. The secretion of these hormones occur cyclically because of the cyclic secretions of pituitary gonadotropins in the female. The fertilised ovum in mammals and other higher animals passes thro..

. Vehicle (vector) DNA is the DNA which carries the passenger DNA to the new host. It is usually the plasmid from bacterial or a bacteriophage. Various enzymes such as lyases, ligases, alkaline phosphates, reverse transcriptases and nucleases are used in the technology. The most widely used nucleas..

. Vehicle (vector) DNA is the DNA which carries the passenger DNA to the new host. It is usually the plasmid from bacterial or a bacteriophage. Various enzymes such as lyases, ligases, alkaline phosphates, reverse transcriptases and nucleases are used in the technology. The most widely used nucleas..

Summary - All higher multicellular animals, called eumetazoans, exhibit a tissue and higher levels of organization There are four primary tissues in animals epithelial, muscular, connective and nervous Epithelial tissue (epithelium) is the simplest. It is avascular and develops from all t..

>The male gamete of one individual fertilizes the female gamete of another individual to produce the zygote. The fertilisation may be external or internal. External fertilisation takes place in animals like the fish and frog where the fertilisation takes place in water, outside the body. ..