Reproductive organs, Biology

Reproductive Organs

In several metazoans, gonads are well-defined. Testes and ovaries take up dissimilar shapes and anatomical dispositions. In cases of certain hermaphrodites similar reproductive tissue from one part may generate sperms and from another part the ova. In sponges, gonads are poorly defined. Sperms and eggs arise from choanocytes and archaeocytes that are transformed into spermatogonia. Sperms leave the sponge by water currents. They enter choanocytes of other sponges that transport the sperms to the egg. Thus fertilisation takes place in situ by the intervention of choanocytes. In cnidarians, testes and ovaries are distinct. In a number of species of Hydra both tests and ovaries may be formed in the same individual (monoecious, bisexual) or in dissimilar individuals but in most species they are found in different individuals (dioecious unisexual). A single ovum produced in the ovary is fertilized in situ by the sperms generally coming from a different hydra. In colonial cnidarians the gonads are formed on the medusae from interstitial cells below the radial canals. They are formed in the epidermis of sub-umbrella. Fertilization is generally external, in water.

Posted Date: 2/5/2013 1:08:40 AM | Location : United States







Related Discussions:- Reproductive organs, Assignment Help, Ask Question on Reproductive organs, Get Answer, Expert's Help, Reproductive organs Discussions

Write discussion on Reproductive organs
Your posts are moderated
Related Questions
Composition of Plant and Animal Tissues Food supplies nutrients popularly known as major and minor nutrients based on the quantities in which they are required for the living b

What is the mRNA sequence to this DNA sequence : Guanine, cytosine, adenine, adenine, thymine, guanine

Planning the Nursing Care   The goals of nursing care are:    Identify the causative factor of megaloblastic anaemia.    Administer appropriate vitamins depending  on

Stages of Research Process: Planning Stage The planning stage of research process  includes a  series of  interdependent steps consisting of 1)  conceptualizatioq of  the r

What is ancylostomiasis? Ancylostomiasis is a disease caused by Ancylostoma duodenale or Necator americanus, both hookworms belonging to the nematode phylum (roundworms). Ancyl

what is test cross?

Utilization of Soy Protein Concentrate Soy protein concentrates are used in food products for  their nutritional characteristics or for their functional properties or for both.

Are there chloroplasts in cyanobacteria? In cyanobacteria there are no chloroplasts and the chlorophyll layers are dispersed in cytosol. Which chemical element is central in


Protozoans - Regeneration in Invertebrates Most single celled animals such as protists, i.e. protozoans, regenerate very well. If part of the cytoplasm is removed from the