Cockroach: reproductive system - female || XI BIOLOGY || CBSE || NEET || AIIMS

Female Reproductive Organs of Cockroach:
The female reproductive system of cockroach (Fig. 73.35) consists of a pair of ovaries, vagina, genital pouch, collaterial glands, spermathecae and the external genitalia.

Periplaneta. Female reproductive organs in dorsal view

(i) Ovaries:
There are two large, light yellow- coloured ovaries lying laterally in the segment 4th, 5th, 6th, embedded in the fat body. Each ovary is formed of a group of eight ovarian tubules or ovarioles containing a chain of developing ova. An ovariole is made up of an epithelial layer resting on a basement membrane and enclosed externally in a connective tissue coat.

However, an ovariole from in front to backwards consists of the following zones:

(i) Suspensory filament, it is thin, thread-like continuation of the connective tissue layer and provides attachment of the ovariole to the dorsal body wall and, thus, it serves to suspend the ovariole in the haemocoel.

(ii) Zone of germarium, it follows the terminal filamentous zone and consists of germ cells or oogonia and mature into oocytes and pushed downwards.

(iii) Vitellarium, this zone receives the oocytes from the zone of germarium one by one and constitutes the largest part of the ovariole, the oocytes become enclosed in a follicle of epithelium and increase progressively in size towards the posterior end which gives it beaded appearance.

(iv) Egg chamber, the vitellarium opens posteriorly into a small, thick, oval egg chamber which contains a single large mature ovum at a time.

(v) Stalk or pedicel, the egg chamber continues posteriorly into thin-walled, hollow stalk which opens into the lateral oviduct.

Oviducts:

The stalk of all eight ovarioles on one side join to form an oviduct which is lateral, small and with muscular wall.

(ii) Vagina:
Both the lateral oviducts unite to form a broad median common oviduct called vagina. The vagina opens by the female gonopore into the genital chamber.

(iii) Genital Pouch:
It is a large boat-shaped structure whose floor is formed by the 7th sternite, roof and sides are formed by the 8th and 9th sternites. The genital pouch can be divided into a genital chamber into which vagina opens and an oothecal chamber where oothecae are formed. The genital chamber also receives the accessory reproductive glands.

The female gonopore is an aperture in the 8th sternum, which lies inside the genital chamber inflected above the 7th sternite. The 7th sternite is also produced backwards into two large oval gynovalvular plates or apical lobes. The genital pouch is also referred to as gynatrium.
(iv) Collaterial Glands:
There is a pair of white much branched collaterial glands, the left is much larger than the right. Both these glands continue as collaterial ducts which join to form a common duct which opens into the dorsal side of the genital chamber. These are the accessory reproductive glands.

(v) Spermathecae:
These are a pair of club-shaped, unequal-sized, one spermathecae being larger than the other, structures. Both the spermathecae unite to form a short common duct which opens into the genital chamber on a small spermathecal papilla. Some workers claim that there is a single spermatheca and it has a lateral caecum.

(vi) External Genitalia of Female:
These lie concealed inside the gynatrium. They consist of an ovipositor formed by two gonapophyses. The ovipositor lies above and behind the gonopore, it is short and has three pairs of elongated processes, a pair of long thick arms lying dorsally and enclosing two pairs of slender tapering arms.

These two pairs of arms arise from a common base and they constitute the posterior gonapophyses, they belong to the 9th abdominal segment and are joined to the 9th tergum.

The third pair of arms of the ovipositor is large, they converge and meet posteriorly lying below the posterior gonapophyses and constitute the anterior gonapophyses. These belong to the 8th abdominal segment and are attached to the outer margins of 8th tergum. The ovipositor is used only to conduct fertilised eggs to the oothecal chamber.

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