Shellfish Breeding and Hatchery Management (2+1)

29.1.2 Male Sex determination and Reproduction

29.1.2 Male Sex determination

The androgenic gland is meut is male and responsible for producing androgenic hormone (AH), which determins all the primary and secondary sexual characters of the male. Although it was first discovered in the males of the amphipod orchestia, the gland is now known to present in all super – order of higher crustaue. Usually it consists at a strand of cells lying along the var differences near it termination, and so between the coxopodite muscles at the last thorak leg; but in some isopods it lies close to the testicular tubues. It is absent in females.

Whenever, the androgenic gland is implemented into a young female it prevents the development of female secondary sexual characters, such as oostegits, and result in masculnization, including a change in the apendages as that of males male condition.

The effect of the hormone is clearly a direct one, since the ovary can be removed prior to implantation without altering the result. If the ovary is not removed, it ceases to produce eggs and instead forms sperm which are fertile and can be used artificially to fertilize normal eggs. Females with implanted andriogenic glands display normal male behaviour and will mate the normal female. They cannot, however, fertilize the females as, although a var deferences with a lumen is developed, it is not functional. Injection of tests without androgenic gland into females has no mascularizing effect.

Reciprocal transplants of ovaries into males give further proof that control of male characteristics is governed slowly by the androgenic gland. Thus, when an ovary is transplanted into a normal male, it is converted into a testis. When an ovary is put into a male which the androgenic gland has been remove, however it remains as an ovary. Finally, removal of the androgenic glands from a male can result in a progressive loss of male secondary characters and in at least one case. Orchestia montag, the tests may become converted into an ovary about a month after the operation.

Injection of steroid, which in mammals have androgenic effects, have no such action in crustacea and, since the histological appearance of the gland resembles that of vertebrate protein – producing cells, it seems possible that the effective hormone is a protein or peptide.

The determination of sex is also influenced by the environmental factors. In the female the androgenic gland does not develop and gonad becomes the ovary.

Reproduction:

One of the obvious features of crustaceans is a thick chitin cuticle (or) exoskeleton. The replacement of the old exoskeleton is accomplished by moulting. In addition moulting is also for the purpose of mating which is usually occur during the reproductive cycle. Whether the moulting is for growth or for purpose of reproduction.