Reproductive organs, Biology

Assignment Help:

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.


Related Discussions:- Reproductive organs

Drought-water stress and adaptations, Drought Drought refers to a condi...

Drought Drought refers to a condition of water shortage and it can result from many reasons. Frequently less than the normal rainfall is a common cause of drought. Less than 75

Psychiatric emergencies, Psychiatric Emergmcy: Psychiatric  Emergmcy i...

Psychiatric Emergmcy: Psychiatric  Emergmcy is  the treatment of disorders of mood, thought and behavior in  an emergency  setting. Psychiatric emergencies are conditions in w

Floristic composition - qualitative characters, Floristic Composition - Qua...

Floristic Composition - Qualitative Characters One of the important qualitative characteristics of a community is its floristic composition. This broadly refers to the kind o

Phylums, characteristics of the Nematoda

characteristics of the Nematoda

How do foods and animals become contaminated with dioxin, Normal 0 ...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Could this be accomplished by passive diffusion, In the human body, the pot...

In the human body, the potassium ion can pass easily through cell membranes, yet the potassium ion concentration is higher inside many cells than it is outside these cells. Could t

What is dietary fibre, Q. What is Dietary fibre? Dietary fibre is defin...

Q. What is Dietary fibre? Dietary fibre is defined as plant polysaccharide resistant to hydrolysis by the digestive enzymes in the human intestinal tract. It includes: • Str

Coronary prevention, a) The West of Scotland Coronary Prevention Study (WOS...

a) The West of Scotland Coronary Prevention Study (WOSCOPS): The study randomized healthy men between the ages of 45 and 64 years with TC levels higher that 252 mg/dL and LDL chole

How dissimilar are intracellular and extracellular digestion, How dissimila...

How dissimilar are intracellular and extracellular digestion? What is the evolutionary benefit of extracellular digestion? Intracellular digestion is that in which the breaking

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd