Cockroach Reproductive System Short 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

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