Cockroach Reproductive System Short Notes | Free Biology Notes

In this article we will discuss about the cockroach reproductive system

Cockroach Reproductive system

• All characters of sexual dimorphism in cockroach present in abdomen
• In male, in addition of anal cerci, 9th sternum bears anal style (unjointed thread like) which are absent in females
• Cockroach are sexual dimorphism. Male and female are separate.

Male Cockroach Reproductive System

• The male cockroach reproductive system of cockroach consists of a pair of testes, vasa deferentia, an ejaculatory duct, utricular gland, phallic gland and external genitalia

Testes

• A pair of three lobed testis located on lateral side in 4-6 abdominal segments
• Testis produces sperms
• Testes become non functional in old adults

Vasa deferentia

• From each testis arises a thin thread-like tube is called vasa deferens
• Both the vasa deferentia meet in the middle and open into an ejaculatory duct

Ejaculatory duct

• Ejaculatory duct is an elongated wide duct
• Opens out by male gonopore situated ventral to the anus

Mushroom gland or utricular

• Large accessory reproductive gland
• Mushroom gland is present in the 6th and 7th abdominal segments of male cockroach
• Located at the junction of vasa deferentia with the ejaculatory duct
• It has a three types of glandular tubules
  • Utriculi majores: peripheral long tubules
  • Utriculi breviores: small short central tubules
  • Seminal vesicles: behind the short central tubules are some short but more bulbous tubules filled with sperms
• Function of these gland is forms inner layer of spermatophore and nourishment to the sperms

Phallic or conglobate gland

• Long and club-shaped accessory gland
• Phallic duct open by a separate aperture
• Involved in the formation of the spermatophore

External genitalia

• Surrounding the male genital pore in the genital pouch there are three chitinous plates called phallomeres
• The phallomeres together constitute the phallic organs or gonapophyses
• These organ help for copulation

Spermatophore

• Sperm produced in testes are stored in seminal vesicle
• All sperms released from seminal vesicles glued together to form a ball called sperm ball
• Long tubules of mushroom gland secrete a membrane around sperm ball called spermatophore
• Small tubules secrete a nutritive fluid in spermatophore
• At the time of copulation spermatophore enters into ejaculatory duct
• Ejaculatory duct secrete another coat on spermatophore and hence it becomes double layered
• When it is released outside from male genital pore then phallic gland secretes another layer, so spermatophore becomes three layered
• They are finally discharged during copulation

Female Cockroach Reproductive System

Ovaries

• One pair of ovaries are situated in 2nd to 6th segments
• Each ovary consists of 8 blind ovarian tubules or ovarioles
• Inside ovarioles series of ova are situated in an acropetal order

Oviducts

• Ovarioles of ovary unite to form short and wide lateral oviduct
• Two lateral oviducts join to form a median common oviduct or vagina in the 7th segment

Vagina

• Posterior wider part of the common oviduct
• Vagina opens into a large genital pouch by female genital pore on the 8th sternum

Genital pouch

• Genital pouch is formed by the 7th, 8th and 9th sternites
• Genital pouch can be divided into two parts
• Genital chamber: anterior part containing female gonopore and pores of spermathecae and collateral glands
• Vestibulum: larger posterior part in which ootheca is formed

Collaterial glands

• A pair of branched accessory reproductive gland
• These glands open into the genital pouch by two separate openings
• The secretion of collateral glands helps in the formation of ootheca

Spermathecae

• A pair of unequal sized spermatheca are associated with genital chamber
• Spermathecae opens into the genital chamber on a small spermathecal papilla
• Responsible for receiving, maintaining, and releasing sperm to fertilize eggs

External genitalia of female

• Situated between the female genital pore and anus inside the genital pouch there are 3 pairs of chitinous plate like structures called gonapophyses or pallomeres
• These gonapophyses help in copulation, egg-laying and in the formation of ootheca.

Copulation

• Breeding season from march to september
• The females secrete sex attracting scent from their scent glands called pheromones or ectohormones
• Male perceive the smell of this scent with help of antennae
• First the male gets under female, extends his hooked phallomere into the female genital chamber
• Sperms are transferred through spermatophores
• Spermatophore remains inside the body of the female for about 20 hours
• During this period all its sperms escape out and fill in the two spermathecae
• Sixteen ova are discharged at a time into the genital pouch
• Simultaneously, sperms stored in the spermathecae are also discharged into the genital pouch to fertilize the ova

Fertilization

• Fertilization is internal
• Fertilized eggs become hardened by the secretion of colleterial glands, which hardens to form an ootheca
• Ootheca is a dark reddish to blackish brown capsule
• They are dropped or glued to a suitable surface
• Development of egg takes place inside ootheca
• Development is indirect, meaning there is development through nymphal stage
• The nymphs look very much like adults, the nymph grows by moulting about 13 times to reach the adult form.
• Nymph changes into an adult in 1 year