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

Illustrate oil-bearing materials, Illustrate oil-bearing materials Oil...

Illustrate oil-bearing materials Oil contents for vegetable oil-bearing materials vary between 18% and 68% of the total weight of the seed, nut, kernel or fruit as indicated i

Preadmission preparation - nursing, Preadmission Preparation   Preadmi...

Preadmission Preparation   Preadmission preparation is most effective when the admission is planned and there is enough time for the nurse to provide necessary information to

Protection of plants against toxic substances, Protection of Plants against...

Protection of Plants against Toxic Substances Plants produce several toxic substances themselves and may also encounter the ones produced by other plants or present in the env

Mode of nutrition, explain the mode of nutrition in paramecium, euglena and...

explain the mode of nutrition in paramecium, euglena and hydra

Oxidation of glyceraldehyde-3-phosphate, Oxidation of glyceraldehyde-3-phos...

Oxidation of glyceraldehyde-3-phosphate Oxidation of glyceraldehyde-3-phosphate : The  conversion  of glceraldehyde- 3-phosphate to  1,3-bisphosphoglycerate  is catalysed  by

What is the parasite that causes giardiasis, Q. What is the parasite that c...

Q. What is the parasite that causes giardiasis? How is it transmitted and what are the typical manifestations of the disease? The Giardiasis is a protozoal infection caused by

Evolution, how to calculate the frequency of mating with the HW equation?

how to calculate the frequency of mating with the HW equation?

Illustrate about the complex partial seizures, State about the Complex part...

State about the Complex partial seizures Complex partial seizures, another type of focal seizure, originate most commonly in the temporal lobe. Complex partial seizures are cha

What is primary structure of a protein, Q. What is primary structure of a p...

Q. What is primary structure of a protein? What is the significance of the primary structure? The primary protein structure is the linear sequence of amino acids that outline t

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