Tag: introduction to reproduction

In almost all frogs, egg fertilization happens outside the female's body instead of inside. The female releases her eggs and the male releases his sperm at the same time. In order to make sure that the sperm reach the eggs, the male and female get into a mating posture called amplexus. The male climbs onto the female's back and clasps his forelegs around her middle. 

In frog growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body. Neurosecretory cells in an insect's brain secrete a hormone, the prothoracicotropic hormone that activates prothoracic glands, which secrete a second hormone, usually ecdysone, that induces ecdysis. PTTH also stimulates the corpora allata, a retrocerebral organ, to produce a juvenile hormone, which prevents the development of adult characteristics during ecdysis.

The frog egg is surrounded by an albuminous layer by an oviduct which later it comes into a uterus. The oviduct is a long coiled duct with the thick wall that is not connected with kidneys.  It consists some glands which secrete albumen that hardens ova. After the ovulation, the cilia of the oviducal funnel draws the coelomic fluid with ova which moves into the middle region with the help of cilia.

The mushroom gland is a large accessory male reproductive gland in the cockroach, which is 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 majors, 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. 

Genital or brood pouch 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 genital pouch of female cockroach can be divided into two parts. The anterior smaller part containing the openings of female gonopore, pores of spermathecae and collateral glands is called genital chamber, while the larger posterior part in which ootheca is formed is called oothecal chamber or vestibulum. Oviduct doesn't open into the genital chamber.