Investigation of Reproduction and Development in AnimalsDue Date: 12/9/96Cycles, Conception and ContraceptionFertility is the condition of being fertile. The aim of contraception is toinhibit fertility in individuals, hence, slowing population growth. The systemby which all female contraception must operate: the menstrual cycle.
What is the menstrual cycle? and what hormones are involved in controlling it?After puberty, the female produces an egg each month. Other changes take placeon a cyclic basis including the uterus lining and hormone levels. These changesare called the menstrual cycle. Follicle stimulating hormone (FSH) from thepituitary gland stimulates the growth of follicles in the ovary. Folliclesproduce oestrogen that stimulates the pituitary to produce leutinising hormone(LH). As LH increases the size of the follicle increases until an egg isreleased. The corpus luteum formed in the follicle secretes progesterone thatprepares the lining of the uterus for pregnancy. If fertilisation does not occurthe lining of the uterus is discharged from the body in the process calledmenstruation.
What is the birth control pill?The combined oral contraceptive pill (the pill) is a reversable, hormonalmethod of birth control.
The pill consists of a mixture of two synthetichormones similar to oestrogen and progesterone, the womans natural hormoneswhich regulate the menstrual cycle. The pill is on of the most popular methodsof birth control.
How does it work?The pill basically prevents ovulation, therefore, the ovaries cant release amature egg. Without an egg for the sperm to fertilize , a woman cannot getpregnant . The hormones also increase cervical mucus, making it difficult forsperm to pass into the uterus.
How effective is the pill?If used correctly, the pill is highly effective. It has a less than one percentfailure rate. However, because many people misuse it, the actual failure rate ismore like three percent. The pill does not provide protection against sexuallytransmitted diseases.
How are pills used?One pill must be swallowed at the same time every day. It is not any singlepill, but the day-to-day process of taking the pill which provides protectionagainst pregnancy.
What is infertility?Infertility in humans and other species(animals) is the inability to concieve orcarry a pregnancy to a live birth. The causes of infertility can be identifiedin some cases. The majority of cases relate to female factors (50%), 40% relateto male factors and 10% aree unknown. Infertility sometimes may serve as acombination of both male and female factors.
If the cause of infertility is known, treatment of some kind may be available.
In other cases a problem may disappear on its own and fertility is restored. Formany couples, about 40% of those affected, there is no solution to theirinfertility.
Now days, there are a range of technologies and options available to coupleswishing to have children of their own. These methods include: donor insemination,IVF ( in vitro fertilisation), ZIFT, GIFT and so on.
What is IVF?IVF involves fertilization outside the body in an artificial environment. Thisprocedure was first used for infertility in humans in 1977,in England. To date,thousands of babies have been delivered as a result of IVF treatment. The IVFprocedure has become simpler, safer and more successful over the years.
What types of infertility can be helped by IVF?IVF is a good option for a couple in several instances. The most common reasonsfor this procedure is blocked or damaged fallopian tubes. Through IVF, thedamaged fallopian tubes are bypassed and the fertilization which usually takesplace within fallopian tubes is now performed in the human embryo culturelaboratory. Other factors that might lead to the need for IVF include low spermcount, endometriosis and unexplained infertility which has not responded toother courses of treatment.
How is procedure carried out?To accomplish pregnancy as a result of IVF several steps are involved:- Stimulation of the ovary to produce several fertilizable eggs. – Retrieval ofthe eggs from the ovary. – Fertilization of the eggs and culture of the embryosin the IVF laboratory. – Placement of the embryos into the uterus forimplantation (embryo transfer or ET).
Bibliography:Encarta Encyclopedia, Microsoft 96 Kinnear, Judith, Book One: Nature of Biology,The Jacaranda Press, Sydney, 1992. Winston, Robert, Infertility, A SympatheticApproach, Optima Book, Great Britian, 1994. World Book Encyclopedia, World BookInc, Chicago, 1991. The Human Body, World Book Inc, Chicago, 1990.
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