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

Is there interphase again between meiosis i and meiosis ii, Is there interp...

Is there interphase again between meiosis I and meiosis II? There is no interphase nor DNA duplication among the divisions of meiosis. Only a short interval called diakinesis h

Dormancy - plant growth substances, Dormancy - Plant Growth Substances ...

Dormancy - Plant Growth Substances Dormancy can be defined as a state of suspended growth and metabolism. When most plants are exposed to seasonal periods of very inclement we

What factor contributed to the current variations, According to the theory ...

According to the theory of natural selection, what factor below contributed to the current variations in beak sizes of finch species on the Galapagos Islands? a. Finches dispersed

Phylum protozoa, PHYLUM  PROTOZOA Definition  and  Introduction  ...

PHYLUM  PROTOZOA Definition  and  Introduction  All  unicellular ( or  acellular )  eukaryotic  animals. Most  primitive (Gr. Protos = first=zoon= animals ) organisms

Egg type, why their is different amount of yolk is present in eggs.

why their is different amount of yolk is present in eggs.

Calculate the length of the implant used, Length of the Implant Used Th...

Length of the Implant Used The length of the implant to be used is dictated by the available bone height. The success rate is proportional to the implant length and the quality

What are the main human diseases caused by fungi, What are the main human d...

What are the main human diseases caused by fungi? The main human diseases caused by fungi are coccidioidomycosis, histoplasmosis, blastomycosis, paracoccidioidomycosis, or Sout

What is the spinal cord, What is the spinal cord? Of which elements is the ...

What is the spinal cord? Of which elements is the spinal cord constituted? The spinal cord is the dorsal neural cord of vertebrates. It is the kind of the central nervous syste

What is the process of breathing, What is the process of Breathing? Oxy...

What is the process of Breathing? Oxygen is supplied to the blood, and carbon dioxide is removed from the blood by the process known as breathing. Air is moved into an exchan

Signs and symptoms of hypothyroidism, Q. What are some signs and symptoms f...

Q. What are some signs and symptoms found in patients with hypothyroidism? In hypothyroidism the production and secretion of T3 and T4 are impaired. Since these thyroid hormone

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