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

fat digestion requires two steps, Fat digestion requires two steps? What a...

Fat digestion requires two steps? What are the steps and what enzymes are used to accomplish each step?

Explain the parental gametes and recombinant gametes, In genetic recombinat...

In genetic recombination by crossing over what is the difference between parental gametes and recombinant gametes? Parental gametes are those gametes that keep the original lin

What is law or theory of demand state, What is law or theory of demand stat...

What is law or theory of demand state? The law or theory of demand states as consumers we derive satisfaction or ‘utility’ like a result of consuming a good or a service. It va

What is the peripheral nervous system, Define the Peripheral Nervous Syste...

Define the Peripheral Nervous System (PNS) Peripheral nervous system consists of cranial and spinal nerves. There are twelve pairs of cranial nerves. They arise from brain.

Why are vaccines used in the prevention, Q. Why are vaccines used in the pr...

Q. Why are vaccines used in the prevention but not in the treatment of infections? Why can antivenom serums be used in prevention and treatment? Vaccines are not used in the tr

Tricuspid excision-types of surgery, Tricuspid Excision :  For tricus...

Tricuspid Excision :  For tricuspid valve endocarditis with vegetations in drug users, valve excision is done by removing three cusps and chordae and papillary muscles. Later

Computed tomography, C omp uted tomography: Computed tomogr...

C omp uted tomography: Computed tomography (CT imaging) is also known as CAT (computed axial tomography) scanning and it is based on the X-ray principle. The CAT sc

Portal hypertension, Portal Hypertension: If you review the portal cir...

Portal Hypertension: If you review the portal circulation you may recall that normal blood flow to and from the liver depends on proper functioning of  the portal vein, the he

Explain ritonavir, Ritonavir (RTV, Norvir)  Ritonavir is well absorbed ...

Ritonavir (RTV, Norvir)  Ritonavir is well absorbed  from the gastrointestinal tract and at full doses potently inhibits HIV, but due to poor tolerability it is now used mainly

What is placebo and nocebo, Problem 1: What is Placebo and Nocebo? Desc...

Problem 1: What is Placebo and Nocebo? Describe the significance of Placebo in clinical trials. Definition of placebo and Nocebo Significance of Placebo in clinical 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