1. The process of a male gamete (sperm) fertilizing a female gamete (egg or ovum)

2.  The cellular union between each gamete ensures that half the genetic makeup of the resulting zygote is derived from each parent.  Ensures genetic variation Dimorphism – different body forms of males and females  Hormones play a role in both development and regulation of sexual physiology

3.  The Reproductive System produces gametes  The structures of the male and the female reproductive system are adapted for production and release of the gametes  In Females: Nurtures and protects the developing embryo

4.  The release of LH (Luteinizing Hormone) stimulates cells to produce increased amounts of testosterone. (Signaled by Hypothalamus)  Testosterone causes the male physical changes associated with puberty  Together with FSH (Follicle-Stimulating Hormone) stimulates the development of sperm

5. Diagram: Page 199 Figure 6.19 Erectile Tissue

6. Menstrual Cycle – the process of egg formation and release  One ovary “usually” produces and releases one mature ovum every 28 days.  The purpose is for fertilization and implantation  Implantation must occur in a highly vascular endometrium  Cycle is regulated by the hypothalamus

7.  The highly vascular endometrium is not maintained if there is no implantation  The breakdown of blood vessels leads to menstruation  Menstruation = not pregnant

8. Ovaries – Primary reproductive organ in females  The hypothalamus produces a hormone known as gonadotrophin releasing hormone (GnRH)  The target of GnRH is the pituitary gland and results in 2 hormones into the blood stream.  LH (Luteinizing Hormone) and FSH (Follicle- Stimulating Hormone) stimulates ovaries  Ovaries produce estrogen

9. Estrogen  Target tissue is the endometrium of the uterus  Results makes endometrium is making it highly vascular  Estrogen causes the female physical changes associated with puberty

10. FSH & LH  Produce structures within the ovaries known as Graafian Follicles  Ovaries contain follicle cells and the reproductive cells known as oocytes  FSH & LH arrange these cells into a structure known as Graafian Follicles

11. FSH & LH  A spike of these hormones causes ovulation Zona Pellucida – an inner ring of follicle cells and a glycoprotein membrane that a glycoprotein membrane that accompanies the oocyte. accompanies the oocyte.  This entire structure is known as a follicle and typically enters the Fallopian tube

12.  The outer ring of follicle cells remain within the ovary  They produce a hormone: Progesterone  Corpus Luteum – structure formed after the same follicle cells continue to divide and fill in the area left by ovulation  Progesterone is continually produced for 10 – 12 days

13. Progesterone  Maintains the thickened, highly vascular endometrium  As long as progesterone is produced enometrium will not beak down waiting for implantation  Estrogen and progesterone are negative feedback for hypothalamus  Hypothalamus does not produce GnRH, so FSH and LH are not produced, Graafian Follicle is not produced

14.  If there is no pregnancy the corpus luteum breaks down  Declines in both progesterone and estrogen  The highly vascular endometrium will not be maintained  Capillaries and small blood vessels begin to rupture and menstruation begins  The drop in progesterone and estrogen signals the hypothalamus to secrete GnRH and the process begins again

17.  Natural fertilization usually occurs in the Fallopian Tubes  24 – 48 hours after fertilization  Some couples cannot bear children because:  Males with low sperm count  Males with impotence  Females who cannot ovulate  Females with blocked Fallopian Tubes  In-vitro fertilization is a fairly new technology used to overcome these issues

18. Steps of an IVF Procedure  To prepare women are injected with FSH for 10 days  This ensures ovulation when you want  Several eggs are harvested surgically  Man ejaculates in a container to collect sperm for fertilization  Harvested eggs are mixed with sperm in culture dishes

19. Steps of an IVF Procedure  Microscopic observation reveals which ova are fertilized and if the early development appears normal and healthy  Usually 2 or 3 healthy embryos are introduced into the woman’s uterus for implantation

20.  The procedure is expensive and using one embryo presents a high risk of failure  That means you have to repeat the procedure  More embryos implanted increases the chances of success: oh and multiple fetuses…..  Healthy not planted embryos can be frozen

21. Ethical Issues For:  It enables couples who would otherwise be unable to have children to have a family  Embryos that are visibly not healthy in the early stages of development can be eliminated from implantation  Genetic screening is possible  Technology will advance and lead to further benefits in reproductive biology  Superbaby???

22. Ethical Issues Against:  Embryos produced during culturing, not implanted are either frozen or destroyed  There are complex legal issues concerning the use of those frozen embryos when couples split up  Genetic screening of embryos could lead to society choosing desirable characteristics  IVF bypasses natures way of decreasing the genetic frequency of that reproductive problem  Multiple births………