Reproduction

Reproduction:

6.6.1 Reproductive systems

The internal reproductive organs in the female include:

Vagina: The vagina is a canal that joins the cervix (the lower part of uterus) to the outside of the body. It also is known as the birth canal.
Uterus (womb): The uterus is a hollow, pear-shaped organ that is the home to a developing fetus. The uterus is divided into two parts: the cervix, which is the lower part that opens into the vagina, and the main body of the uterus, called the corpus. The corpus can easily expand to hold a developing baby. A channel through the cervix allows sperm to enter and menstrual blood to exit.
Ovaries: The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones.
Fallopian tubes: These are narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus. Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. The fertilized egg then moves to the uterus, where it implants into the lining of the uterine wall.

1: Ovary
2: Medial surface
3: Lateral surface
4: Free border
5: Mesovarial margin
6: Tubal extremity
7: Uterine extremity
8: Oviduct (fallopian tube)
9: Opening of fallopian tube
10: Infundibulum of fallopian tube
11: Fimbriae of fallopian tube
12: Ovarian fimbria
13: Ampulla of fallopian tube
14: Isthmus of fallopian tube
15: Uterine part of fallopian tube
16: Uterine opening of fallopian tube

Ovulation animation: http://www.argosymedical.com/flash/ovulation/landing.html

Spermatagonium - parent cells for sperm that do meiosis 1 and 2 each one makes 4 sperm sperm is made when testosterone receptors in the cells are triggered
Testes - male reproductive glands where sperm are produced, 20 feet of tubes in each testicle
Semiferious tubules - Tiny tubes in the testes where sperm cells are produced, grow and mature
Leydig Cells - Cells of the testis lying between the testicular tubules in which sperm are formed
Sertoli Cells - Cells lining the seminiferous tubules which produce immature sperm sperm
Epididymis - The long, coiled tube that rests on the back side of each testicle. It transports and stores the sperm cells produced in the testes, and brings them to maturity
Vas deferens - The long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the urinary bladder, pushes sperm to the urethra
Semen- A thick fluid, containing a mixture of glandular secretions and sperm cells
Seminal vesicles - Paired glands located on either side of the prostate that secrete substances to nourish sperm
Prostate gland - The prostate secretes a thin, opalescent, slightly alkaline fluid which forms part of the semen
Hormonal Control of the testes (GnRH, FSH, LH, testosterone) (978-Figure)
Hypothalamus - part of the brain, the hormonal regulation center, located adjacent to and above the pituitary gland, secretes GnRH

Cell type	ploidy/chromosomes	chromatids	Process
spermatogonium (types Ad, Ap and B)	diploid/46	2N	spermatocytogenesis (mitosis)
primary spermatocyte	diploid/46	4N	spermatidogenesis (meiosis 1)
secondary spermatocyte	haploid/23	2N	spermatidogenesis (meiosis 2)
spermatid	haploid/23	1N	spermiogenesis
sperm	haploid/23	1N	spermiation

Males reproductive system animation: http://health.howstuffworks.com/adam-200136.htm

Sperm production animation; http://health.howstuffworks.com/adam-200017.htm

Sperm production animations: http://www.argosymedical.com/flash/Sperm/landing.html

Spermatogenesis 1 animation: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__spermatogenesis__quiz_1_.html

6.6.2 & 6.6.3 Hormones in menstrual cycle

	What Happens During the Menstrual Cycle? Females of reproductive age experience cycles of hormonal activity that repeat at about one-month intervals. (Menstru means "monthly"; hence the term menstrual cycle.) With every cycle, a woman's body prepares for a potential pregnancy, whether or not that is the woman's intention. The term menstruation refers to the periodic shedding of the uterine lining. The average menstrual cycle takes about 28 days and occurs in phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase. There are four major hormones (chemicals that stimulate or regulate the activity of cells or organs) involved in the menstrual cycle: follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone. Follicular Phase of the Menstrual Cycle: This phase starts on the first day of the period. During the follicular phase of the menstrual cycle, the following events occur: Two hormones, follicle stimulating hormone (FSH) and luteinizing hormone (LH) are released from the brain and travel in the blood to the ovaries. The hormones stimulate the growth of about 15-20 eggs in the ovaries each in its own "shell," called a follicle. These hormones (FSH and LH) also trigger an increase in the production of the female hormone estrogen. As estrogen levels rise, like a switch, it turns off the production of follicle-stimulating hormone. This careful balance of hormones allows the body to limit the number of follicles that complete maturation, or growth. As the follicular phase progresses, one follicle in one ovary becomes dominant and continues to mature. This dominant follicle suppresses all of the other follicles in the group. As a result, they stop growing and die. The dominant follicle continues to produce estrogen. Ovulatory Phase of the Menstrual Cycle: The ovulatory phase, or ovulation, starts about 14 days after the follicular phase started. The ovulatory phase is the midpoint of the menstrual cycle, with the next menstrual period starting about 2 weeks later. During this phase, the following events occur: The rise in estrogen from the dominant follicle triggers a surge in the amount of luteinizing hormone that is produced by the brain. This causes the dominant follicle to release its egg from the ovary. As the egg is released (a process called ovulation) it is captured by finger-like projections on the end of the fallopian tubes (fimbriae). The fimbriae sweep the egg into the tube. Also during this phase, there is an increase in the amount and thickness of mucous produced by the cervix (lower part of the uterus.) If a woman were to have intercourse during this time, the thick mucus captures the man's sperm, nourishes it, and helps it to move towards the egg for fertilization. Luteal Phase of the Menstrual Cycle: The luteal phase of the menstrual cycle begins right after ovulation and involves the following processes: Once it releases its egg, the empty follicle develops into a new structure called the corpus luteum. The corpus luteum secretes the hormone progesterone. Progesterone prepares the uterus for a fertilized egg to implant. If intercourse has taken place and a man's sperm has fertilized the egg (a process called conception), the fertilized egg (embryo) will travel through the fallopian tube to implant in the uterus. The woman is now considered pregnant. If the egg is not fertilized, it passes through the uterus. Not needed to support a pregnancy, the lining of the uterus breaks down and sheds, and the next menstrual period begins.
	GnRH (Gonadotropin-releasing hormone) - Gonadotropin-releasing hormone (GnRH), also known as Luteinizing-hormone releasing hormone (LHRH), is a tropic peptide hormone responsible for the release of FSH and LH from the anterior pituitary. GnRH is synthesized and released from neurons within the hypothalamus. FSH (follicle stimulating hormone)- FSH stimulates the growth and recruitment of immature Ovarian follicles in the ovary. It is released by pituitary, receptors on the cells of the follicle and egg that trigger these cells to grow and the egg to start meiosis II. As the follicle matures, one becomes dominant. It releases inhibin and estradiol, both of which decrease FSH production by inhibiting GnRH production in the hypothalamus Estrogen - A hormone that promotes the development and maintenance of female sex characteristics, when a high level of estrogen is reached the anterior pituitary releases a surge of LH. They promote the development of female secondary sex characteristics, such as breasts, and are also involved in the thickening of the endometrium and other aspects of regulating the menstrual cycle. LH (luteinizing hormone) - this surge triggers the cells in the follicle to go through ovulation, the follicle is left Progesterone – after ovulation the levels go up, it makes sure that the lining of the uterus remains thick and that there’s a place for the fertilized egg to go, after 14 days no progesterone is produced and menstruation occurs Progesterone- Under the influence of progesterone, the endometrium (uterine lining) changes to prepare for potential implantation of an embryo to establish a pregnancy · Progesterone is sometimes called the "hormone of pregnancy" and it has many roles relating to the development of the fetus: · Progesterone converts the endometrium to its secretory stage to prepare the uterus for implantation. At the same time progesterone affects the vaginal epithelium and cervical mucus, making the mucus thick and impermeable to sperm. If pregnancy does not occur, progesterone levels will decrease, leading, in the human, to menstruation. Normal menstrual bleeding is progesterone withdrawal bleeding. · During implantation and gestation, progesterone appears to decrease the maternal immune response to allow for the acceptance of the pregnancy. · Progesterone decreases contractility of the uterine smooth muscle. · In addition progesterone inhibits lactation during pregnancy. The fall in progesterone levels following delivery is one of the triggers for milk production. · A drop in progesterone levels is possibly one step that facilitates the onset of labor.

Oogenesis: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__maturation_of_the_follicle_and_oocyte.html

Menstrual cycle animation: http://health.howstuffworks.com/adam-200132.htm

Menstrual cycle interaction: http://msnbcmedia.msn.com/i/msnbc/Components/Interactives/Health/WomensHealth/zFlashAssets/menstrual_cycle_dw2%5B1%5D.swf

ovulation animation: http://health.howstuffworks.com/adam-200064.htm

Egg production animation: http://health.howstuffworks.com/adam-200017.htm

Conception animation: http://health.howstuffworks.com/adam-200112.htm

6.6.4 Role of testosterone

Prenatal androgen effects. Most of the prenatal androgen effects occur between 7 and 12 weeks of gestation.

· Genital virilization (midline fusion, phallic urethra, scrotal thinning and rugation, phallic enlargement); although the role of testosterone is far smaller than that of Dihydrotestosterone.

· Development of prostate and seminal vesicles

Pre- Peripubertal effects. Pre- Peripubertal effects are the first visible effects of rising androgen levels at the end of childhood, occurring in both boys and girls.

· Adult-type body odour

· Increased oiliness of skin and hair, acne

· Pubarche (appearance of pubic hair)

· Axillary hair

· Growth spurt, accelerated bone maturation

· Develop hair on upper lip and sideburns.

Pubertal effects. Pubertal effects begin to occur when androgen has been higher than normal adult female levels for months or years. In males these are usual late pubertal effects, and occur in women after prolonged periods of heightened levels of free testosterone in the blood.

· Enlargement of sebaceous glands. This might cause acne.

· Phallic enlargement or clitoromegaly

· Increased libido and frequency of erection or clitoral engorgement

· Pubic hair extends to thighs and up toward umbilicus

· Facial hair (sideburns, beard, moustache)

· Chest hair, periareolar hair, perianal hair

· Leg hair & Axillary hair (underarm)

· Subcutaneous fat in face decreases

· Increased muscle strength and mass

· Deepening of voice

· Increase in height

· Growth of the Adam's apple

· Growth of spermatogenic tissue in testes, male fertility

· Growth of jaw, brow, chin, nose, and remodeling of facial bone contours

· Shoulders become broader and rib cage expands

· Completion of bone maturation and termination of growth. This occurs indirectly via estradiol metabolites and hence more gradually in men than women.

Adult testosterone effects. Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Some of these effects may decline as testosterone levels decline in the later decades of adult life.

· Libido and clitoral engorgement/penile erection frequency.

· Regulates acute HPA response under dominance challenge

· Mental and physical energy

· Maintenance of muscle trophism

· The most recent and reliable studies have shown that testosterone does not cause Prostate cancer, but that it can increase the rate of spread of any existing prostate cancer.Recent studies have also shown its importance in maintaining cardiovascular health.

· Under dominance challenge, may play a role in the regulation of the fight-or-flight response

6.6.5 In vitro fertilization

In vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside of the womb, in vitro. IVF is a major treatment in infertility when other methods of assisted reproductive technology have failed. The process involves hormonally controlling the ovulatory process, removing ova (eggs) from the woman's ovaries and letting sperm fertilize them in a fluid medium. The fertilized egg (zygote) is then transferred to the patient's uterus with the intent to establish a successful pregnancy. The first test tube baby, Louise Brown, was born in 1978.

In vitro fertilization animation: http://www.muschealth.com/video/Default.aspx?videoId=10081&cId=34&type=rel

In vitro fertilization animation: http://www.sumanasinc.com/webcontent/animations/content/invitrofertilization.html

6.6.6 Ethics of in vitro fertilization

Wikipedia: http://en.wikipedia.org/wiki/IVF

Goldworth: Ethics of in vitro fertilization

What Happens During the Menstrual Cycle?

Follicular Phase of the Menstrual Cycle: This phase starts on the first day of the period. During the follicular phase of the menstrual cycle, the following events occur:

Ovulatory Phase of the Menstrual Cycle: The ovulatory phase, or ovulation, starts about 14 days after the follicular phase started. The ovulatory phase is the midpoint of the menstrual cycle, with the next menstrual period starting about 2 weeks later. During this phase, the following events occur:

Luteal Phase of the Menstrual Cycle: The luteal phase of the menstrual cycle begins right after ovulation and involves the following processes:

Prenatal androgen effects. Most of the prenatal androgen effects occur between 7 and 12 weeks of gestation.

Pre- Peripubertal effects. Pre- Peripubertal effects are the first visible effects of rising androgen levels at the end of childhood, occurring in both boys and girls.

Pubertal effects. Pubertal effects begin to occur when androgen has been higher than normal adult female levels for months or years. In males these are usual late pubertal effects, and occur in women after prolonged periods of heightened levels of free testosterone in the blood.

Adult testosterone effects. Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Some of these effects may decline as testosterone levels decline in the later decades of adult life.