Reproductive mechanism of Earthworm
Reproduction in EarthwormEarthworm are monoecious or hermaphrodite or bisexual.However, self-fertilization no occur due to the fact that of relative location of male and female reproductive organs and it is protandrous.Protandrous ad the condition where male reproductive guts mature earlier than the mrs ones.Thus, overcome fertilization wake up in earthworm.It comprises of masculine reproductive organs and female reproductive organs.
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Male Reproductive guts of Earthworm:The masculine reproductive offal comprises the testes, testis sacs, seminal vesicles, spermiducal funnel, vasa deferentia, prostate glands and also accessory glands.The masculine reproductive guts include:
|Testis||2 pairs||10th and also 11th segment|
|Testis sacs||1 pair||10th and also 11th segment|
|Seminal vesicles||2 pairs||11th and 12th segment|
|Spermiducal funnels||2 pairs||10th and also 11th segment|
|Vasa differentia||2 pairs||10/11th come 18th segment|
|Prostate glands||1 pair||16/17th come 20/21th segment|
|Accessory glands||2 pairs||17th and also 19th segment|
|Common prosatic ducts||1 pair||18th segment|
|Male genital aperture||1 pair||18th segment|
i. Testes:Testes are very minute frameworks that are whitish in colour.There space two pairs of testes and they are lobed.One pair each is existing in segment 10th and also 11th the are discovered attached through the posterior surface ar of 9/10 and 10/11 inter-segmental septa.Each testis possess 4-8 finger like lobules that includes rounded cell in masses termed as spermatogonia.Testes are enclosed within testis sac.During the young stage of the earthworm, the testes are fully developed conversely, they acquire degenerated in the adult stage.
ii. Testis sacs:Testis sacs room whitish, broad bilobed sacs the encloses testis.They are thin-walled and fluid-filled sacs.On the ventrolateral political parties of the ventral nerve cord, the 2 testis sacs are located in the 10th and 11th segment beneath the stomach.In the testis sac, a big spermatic funnel having actually folded and ciliated spare part is present behind each of the four testes.The testis sacs links with a pair that seminal vesicles.The spermatogonia are casted right into the testis bag then, they are passed right into the seminal vesicles.
iii. Seminal vesicles:These space large, whitish spherical structures.These are discovered in 2 pairs, every pair is located in 11th and also 12th segment.The testis sacs open right into seminal motor by a narrow duct.The posterior seminal engine are bigger than the anterior ones.The seminal engine of the 11th segment are present enclosed in the posterior larger testis sac.The seminal motor of the 12th segment space exposed in the coelomic cavity.These are located ventro-laterally below the stomach.They are additionally termed together septal pouches, together they construct as septal outgrowths.The spermatogonia native testis sac are received by seminal vesicles.Seminal engine aids because that nourishment to the sperm.Here, the spermatogonia matures and form spermatozoa.
iv. Spermiducal funnel/ spermatic funnel:They room cup like curvature in structure and also are existing in 2 pairs.Each spermiduct funnel is within ciliated.It is located listed below each testis in the segment 10th and also 11th segment.It is uncovered enclosed in ~ the exact same testis sac.It help in conduction that spermatozoa.After the maturation, sperms from seminal motor revert come testes sac and pass into vasa differentia via spermiducal funnel.
v. Vasa deferentia:It is thin, long, narrow, thread prefer tubular structure.Posteriorly, each spermiducal funnel leads to vasa deferens.These are found in two pairs and also each pair is located on the either side of the alimentary canal.Both the pair of vasa deferentia runs in nearby proximity and laterally to the nerve cord listed below the alimentary canal ~ above the ventral body wall.It extends native 12th come 18th segment and also meets prostatic duct in the 18th segment forming common prostatic and also spermatic duct.The sperms from spermatic funnel are accumulated by the vasa deferentia and also are provided to prostate glands.
vi. Prostate glands:Prostate glands space large, whitish, flat solid, irregularly shaped glands.These are uncovered in pair and also are situated one on either next of the alimentary canal in the segments from 16th to 20th or 17th to 21st .Maximum section of prostate glands space glandular region while a small component is non-glandular region.A thick curved prostatic duct arises from each prostate gland in 18th segment.The prostatic duct is linked to the two vasa deferntia that its own side and forms a usual prostatic and also spermatic duct.On the ventral next of 18th segment, prostatic duct opens via a male genital aperture.Hence, each genital aperture has actually three distinctive apertures, 2 of the vasa deferentia and also one of the prostatic gland.In earthworm the prostatic cheap is valuable for the activation that sperms.It additionally aids in motility that sperms.
vii. Accessory Glands:Accessory glands space rounded structures and are found in two pairs.Each pair is located in the segment 17th and 18th on the ventral body wall at the lateral political parties of the nerve cord.These glands space exposed to outside by a arsenal of little ductless glands. On the 2 pairs the genital papillae positioned externally ~ above either side of the mid-ventral line, these glands open up in the 17th and 19th segments.The cheap of these glands is assumed to host the 2 worms together throughout the copulation process.After the perfect of spermatogenesis, tailed spermatozoa space formed.These spermatozoa again enter the testis sacs and also reach the vasa deferentia via the spermatic funnels.Then they are discharged with the male genital apertures along with the prostate glands’ secretion.Male genital pores are found in pairs and also is situated in 18th segment.
Female Reproductive organs of Earthworm:Female reproductive guts consist of the ovaries, oviducal funnel, oviducts and spermathecae.Female reproductive body organ includes:
|Ovaries||1 pair||13th segment|
|Oviducal funnels||1 pair||13th segment|
|Oviducts||1 pair||13th and also 14th segment|
|Female genital aperture||single||14th segment|
|Spermathecae||4 pairs||6th, 7th, 8th, and 9th segment ventrolaterally|
i. Ovaries:Ovaries are white, small, lobulated frameworks that are found in a pair.In the 13th segment, ovaries are situated one ~ above either side of the ventral nerve cord.It is attached v the posterior an ar of the inter-segmental septum of 12/13 segments.Each ovary is composed of various finger like projections where occurring ova are discovered in a row, offering the beaded appearance.In each ovarian lobe, the ova exhibits number of stages that its development where mature people lie in the distal component and the immature people are discovered in the proximal part.
ii. Oviducts:A small, ciliated ovarian funnel with folded margins space present below each ovary in 13th segment.Each ovarian funnel opens right into a short and also conical oviduct.Oviducts room ciliated.The oviducts of both the political parties unite listed below the nerve cord.Here, it open by a solitary median mrs genital spicy ventrally in the 14th segment.The ova after maturation room released indigenous the ovaries and also are obtained by the ovarian funnel.Then, the passes through the oviduct and also that is discharged the end via the mrs genital pore.
iii. Spermathecae:Spermathecae are four pairs and also each pair is situated ventro-laterally in the 6th, 7th, 8th, and 9th segments.Each spermatheca is flask shame structure.Each spermathecum is made of ampulla and also neck (upper quick tubular part).the key body is the ampulla.At the junction that the ampulla and neck, a tiny sac is found.This sac is termed together diverticulum.Spermathecae are also termed together seminal receptacles together they space designed for receiving sperms from an additional worm throughout copulation and also temporary warehouse of sperms.The diverticulum of spermathecae in Pheretima posthuman stores sperms, which reach right here after copulation.But in other varieties of earthworm, sperms space store in ampulla.In Pheretima posthuma ampulla aids nourishment to the sperm yet in other varieties of earthworm, diverticulum gives nourishment.Spermathecal duct opens external by tiny pores situated in the grooves the 5/6, 6/7, 7/8, and 8/9 segments.
iv. Female genital pore:It is solitary pore and is located in the 14th segment.
Copulation in Earthworm:Copulation has been checked out in several types of earthworms.It typically take location in the rainy season during the months of July come October, in the morning hours before sunrise.During copulation, 2 earthworms lie opposite come each other in together a method that your ventral surfaces remain in touch and male genital openings that one comes just opposite come the spermathecal openings the the other and also vice versa.Both the earthworms receive sperms and also prostatic secretion in every one of their spermathecae through a protuberance that arises from the male genital opening.Copulation big for about an hour.Sperms space stored in the spermathecae.
Cocoon formation in Earthworm:Fertilization only occurs in the cocoon or ootheca and also is always external.After tires of ovaries, cocoon or ootheca development starts after copulation.Three arrays of glands are existing in the epidermis the clitellar segments, i.e., 14th , 15th and 16th segments.They are mucous glands the secrete mucus for copulation, cocoon-secreting glands that produces the wall surface of the cocoon and also albumen glands that secrete albumen in which eggs space deposited in the cocoon.A cocoon of earthworm contains many fertilized eggs.However, only one creates into embryo, while other fertilized eggs serve nutritive/ nurse cells.Cocoon-secreting glands the the clitellum secretes a membranous girdle.This girdle ~ hardening, the deposition the albumin in between the girdle and also the body wall surface takes place.The worm begins to retract itself backwards native the girdle.As the girdle moves end the woman genital pore, it receives eggs, and when the passes end the spermathecae, sperms are emitted right into it v spermathecal pores.Finally, the girdle is eliminated off indigenous the anterior end of the worm.In a short time, the elasticity of its wall surface closes increase its two ends forming a cocoon or ootheca.Several cocoons formation occurs after every copulation as the spermatozoa current in the spermatheca carry out not relocate out every at one time.The cocoons room oval in structure, light yellow in colour and are around 2 to 2.4 mm in length and 1.5 to 2 mm in breadth.
Fertilization in earthworm:Fertilization occurs inside the cocoon and also normally over there is just one embryo in a cocoon.Cocoon is uncovered in moist and also cool places and young one hatch out after 2-2.5 months.Albumen cells administer nutrition to the embryo.Cleavage is holoblastic and unequal.Development is straight without any larval stage.
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