Reproductive System of Insects

and Earthworms

Reproductive System

of Insects

• How insects reproduce?

IntroductionThe reproductive organs of the insects are similar in structure and function to those vertebrates

Both types of gametes are haploid and unicellular ,both eggs are larger in volume than sperm.

Most insect species reproduce sexually by internal fertilization

Functions of Male Reproductive System

Production of spermStorage of spermDelivery of sperm in the female

The male ‘s reproductive system contains a pair of testes , usually located near the back of the abdomen.

Each testes is subdivided into functional units

( follicles) where sperm is actually produced.Near the distal end of

each follicle, there are a group of germ cells (spermatogonia) that divided by mitosis and increase in size to form spermatocytes

• These spermatocytes migrate toward the basal end of the follicle ,pushed along to the continued cell division of the spermatogonia.

• Each spermatocytes undergoes meiosis :this yield for haploid spermatids which develop into mature spermatozoa as they progress into along through the follicle.

• One or more pairs of accessory glands are usually associated with the males reproductive system.

• These are secretory organs that connect the reproductive system by means of the short ducts-some may attached near the testes, or seminal vesicles, others maybe associated with the ejaculatory duct.

1. Manufacture of seminal fluid, a liquid medium that sustains and nourishes mature sperm while they are in the male's genital system.

The glands have two major functions:

2. Production of spermatophores, pouch-like structures (mostly protein) that encase the sperm and protect them as they are delivered to the female's body during copulation.

• Mature sperm pass out of the testes through short ducts (vasa defferentia) and collect in storage chambers (seminal vesicles) that are usually little more than enlarged sections of the vasa.   Similar ducts (vasa deferentia) lead away from the seminal vesicles, join one another near the midline of the body, and form a single ejaculatory duct that leads out of the body through the male's copulatory organ (called an aedeagus).

Female Reproductive System

The female's reproductive system contains a pair of ovaries, accessory glands, one or more spermathecae, and ducts connecting these parts.

• Each ovary is subdivided into functional units called ovarioles., where the eggs actually produced.• Near the distal

end of each ovariole, there are a group of germ cells (oogonia) that divide by mitosis and increase in size to form oocytes.

• Each oocytes undergoes meiosis: this yield for cells-one egg and three polar bodies.

• The polar bodies may disintegrate or they may accompany the egg as the nurse cell.

• As developing eggs move down the ovariole,they grow in size by absorbing yolk

• Mature eggs leaves the ovaries through short lateral oviducts.

• Near the midline of the body, these lateral oviducts joint to form a common oviduct which open into a genital chamber called the bursa copulatrix.

• Female accessory glands (one or more pairs) supply lubricants for the reproductive system and secret a protein –rich egg cell(chorion) that sorrounds the entire egg.

• These glands are usually connected by small ducts or the common oviduct or the bursa copulatrix.

• During copulation, the male deposits his spermatophore in the bursa copulatrix.

• Peristaltic contractions force the spermatophore into females spermatheca.

• A spermathecal gland produces an enzyme (for digesting the protein coat of the spermatophore ) and nutrients ( for sustaining the sperm while they are in storage).

• Sperm may live in the spermatheca for weeks ,months or even a year.

• During ovulation ,each egg passes across the opening to the spermatheca and stimulates release of a sperm onto the egg surface.

• Fertilization occurs as soon as one sperm ‘s nucleus fuses with the egg cell’s nucleus.

• Oviposition (egg laying) usually follow s closely after fertilization.

• Once these process are complete ,the egg is ready to begin embryonic development.

Types of Reproduction

• Paedogenesis-reproduction by larval insects.

• Parthenogenesis- development without fertilization- unfertilized eggs produced:

*males*females*both

• Polyembryony

Mating• Monogamous

- when females of some species are essentially mate ones.• Polygamous

- when female insects mate several to many times.

Video--8. Insect reproductive systems -

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Reproductive System

of Earthworm

•How earthworm reproduce?

Earthworms -reproduce sexually. They cannot

reproduce asexually. -they are hermaphrodite

(monoecious) both ovaries and testes are found in the same individual.

-they are protandrous, the male sex cells mature much earlier than the female cells, therefore, self-fertilization is not possible..

Male Reproductive

SystemThe male reproductive

system comprises testes, testis sacs, seminal vesicle, vasa deferentia, prostate gland and accessory glands.

Female Reproductive

System• The female reproductive

organs are ovaries, oviducal funnels, oviducts and spermathecae.

I already told you about my clitellum, that whitish band near my anterior (head) end. It forms when I am about 4 to 6 weeks old. It has both male and female reproductive organs. (That means I am neither a boy or girl, I am both).

When mating, another worm and I join together with heads pointing in opposite directions. Sperm is passed from one worm to the other and stored in sacs. Then a cocoon forms on each of us on our clitellum. As we back out of the narrowing cocoons, eggs and sperm are deposited in the cocoon.

After we back out, the cocoon closes and fertilization takes place. The cocoons are much smaller than a grain of rice and are yellow-colored. Each cocoon can have 1-5 worms. If conditions are not right for hatching, such as dryness, my cocoons can be dormant for years and hatch when conditions are right.

My babies will hatch in 2-3 weeks. The new baby worms are whitish, and you can practically see through them (but I think they are beautiful, just like any parent). My babies are only 1/2 to one inch long. They are on their own as soon as they are born. In about six weeks, they will produce their own baby worms. I'll be a grandparent and the cycle starts all over again.

How do earthworms reproduce and what is their life cycle?

VideoReproductive System of Earthworm 512 1 -

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References:

http://en.wikipedia.org/wiki/Insect_reproductive_systemhttp://passscience.blogspot.com/2010/09/reproductive-system-of-earthworm.html http://classes.uofk.edu/file.php/707/The_Reproductive_System_of_Insects.pdfhttp://www.cals.ncsu.edu/course/ent425/library/tutorials/internal_anatomy/reproductive.html

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