Describe male reproductive system of cockroach
Answers
The male reproductive system of cockroach consists of a pair of testes, vasa deferentia, an ejaculatory duct, utricular gland, phallic gland and the external genitalia.
★Testes:
There is a pair of three-lobed testes lying dorsolaterally in the 4th and 5th abdominal segments, being embedded in the fat body. The testes are well developed and elaborate structures in young cockroach and they are full of sperms. The testes become non-functional and reduced in old adults but some sperms may still be found in them.
★ Vasa Deferentia:
From each testis arises a thin thread-like, white vasa deferens. Both the vasa deferentia pass backwards almost to the posterior end of abdomen and then bend forwards to meet in the middle and open into an ejaculatory duct.
★ Ejaculatory Duct:
The ejaculatory duct is an elongated wide median duct which runs backwards in the abdomen and opens out by male gonopore situated ventral to the anus.
★ Utricular or Mushroom-shaped Gland:
It is a large accessory reproductive gland, whitish in colour and situated at the junction of vasa deferentia with the ejaculatory duct. It has a mass of glandular tubules of three kinds, the peripheral long tubules or utriculi majores, the central tubules are small short tubules or utriculi breviores and behind the short central tubules are some short but more bulbous tubules forming the seminal vesicles filled with sperms.
★ Phallic or Conglobate Gland:
It is a long and club-shaped accessory gland. Its anterior broader end lies in the 6th segment slightly to the right of the nerve cord. It narrows posteriorly into a tubular structure and finally tapers to open by a separate aperture located close to the male gonopore at the hind end of the body.
★ External Genitalia:
Some chitinous asymmetrical structures are found surrounding the male gonopore at the end of the abdomen. These are three phallomeres or male gonapophyses which constitute the external genitalia.
Right Phallomere:
It is mid-dorsal in position. It has two chitinous but membranous horizontal opposing plates and a broad serrate lobe with a saw- toothed edge and two large teeth, and at its posterior side it has a sickle-shaped hook.
Left Phallomere:
It has a broad base from which several structures arise, on the extreme left is a long slender arm with a curved hook called titillator, next to the titillator is a shorter and broader arm ending in a black hammer-like head called pseudopenis.
Close to the pseudopenis are three small soft lobes, one of which bears a hook and is called an asperate lobe. The duct of the phallic gland traverses the left phallomere and opens between the asperate lobe and pseudopenis.
Ventral Phallomere:
It is very simple in structure and lies partly below the right phallomere. It has a large brown plate and bears the male gonopore
Spermatophore:
The sperms produced from testes, while the cockroach is still young, are brought by the vasa deferentia into the seminal vesicles for storage. The sperms in the seminal vesicles are glued together in the form of bundles called spermatophores. Actually, the spermatophores are discharged by the male during copulation.
A spermatophore is pear-shaped about 13 mm in diameter and its wall has three layers.
Its innermost layer is first formed by the milky secretion secreted from the long peripheral tubules of the utricular gland. This layer then receives bundled sperms from seminal vesicle and a liquid from the short tubules of the utricular gland. Then this inseminated layer passes down the ejaculatory duct and it receives the second layer from the cells of ejaculatory duct.
During mating, the two layered spermatophore, thus, formed is attached to the spermathecal aperture of the female and then the secretion of phallic gland is poured over it which hardens to form the third and outermost layer of the spermatophore