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

Modes of nitrate reductase and nitrite reductase, Modes of NO - 3 reducti...

Modes of NO - 3 reduction Accordingly, there are the following three basic modes of NO - 3 reduction. Directly dependent upon photosynthesis as in cyanobacter

Explain the concept of menu planning, Explain the Concept of Menu Planning?...

Explain the Concept of Menu Planning? You have learnt from the previous units that our body's many functions, be it physical activity, mental exercise, growth (in the case of c

Factors influencing metabolism, Let us learn about the factors that affect ...

Let us learn about the factors that affect metabolism: 1) More energy is required when muscular work is carried out. 2) The larger the surface area of the body, more heat is

Human milk composition and infant growth and development, Explain the Human...

Explain the Human Milk Composition and Infant Growth and Development? This sub-section deals with composition of human milk, compares human milk with cow's milk and why human m

Describe nerve cells, In eukaryotes possibly the most rapid and complex sig...

In eukaryotes possibly the most rapid and complex signaling is mediated through nerve impulses.  The Nerve  cells  (neurons)  consist  of  a cell  body  with  numerous projections

Explain arterial continuous mummer, Explain arterial continuous mummer? ...

Explain arterial continuous mummer? Arterial Continuous Mummer : These originate in constricted arteries as in carotid or femoral artery obstruction (Mummer are louder in sys

Determine the psychological problems, Psychological Problems Failure to...

Psychological Problems Failure to fulfill the patient's expectations and failure to gain the patient's acceptance and satisfaction constitutes a psychological failure. It is hi

How does poliomyelitis affect the neural transmission, Q. How does poliomye...

Q. How does poliomyelitis affect the neural transmission in the spinal cord? The poliovirus destroys and parasites spinal motor neurons causing paralysis of the muscles that de

Define end and the beginning of the first interphase period, Q. What are th...

Q. What are the events that mark the end and the beginning of the first interphase period? What happens inside the cell in this period? The initial interphase period is the G1.

List the routine treatment sequence for an implant patient, List the routin...

List the routine treatment sequence for an implant patient. The different phases are - Preliminary treatment - Stage I surgical phase - Stage II surgery and Prosthetic

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