1. The
Reproductive
System

2. Animal Reproductive Strategies
Sexual Reproduction
Asexual Reproduction
Fission
Budding

3. Different Reproductive Strategies
Parthenogenesis
Common in many species of arthropods
Females produce offspring from unfertilized eggs
Honeybees
Hermaphroditism
Individual has both ovaries and testes
Tapeworms and earthworms
Fish
Protogyny
Protandry
Some species are exclusively parthenogenic and some switch between sexual and parthenogenesis
Queen bee mates only once and stores the sperm so that she can control the release of the sperm. If no sperm are released then the eggs develop parthenogenically.
(Parth. Produces haploids)
Tapeworm can fertilize itself because it is unlikely to encounter another tapeworm.
Two earthworms are required because each functions as both male and female during reproduction and both leave the encounter with fertilized eggs.
Protogyny- change from female to male
Protandry- male to female

4. Sex Determination SRY gene is important
If no functional SRY gene is present, the organism will be a female
SRY gene – sex determining region of the Y chromosome, basically determines if its male or not.

5. Vertebrate Fertilization and Development
External fertilization
Female fish release their eggs and males release their sperm into the water, where they meet
Internal fertilization
Introduction of male gametes directly into the female reproductive tract
Internal- vertebrates began to live on land, and gametes couldn’t be released externally because they would dry up and die. Vertebrates evolved to sexually fertilize and reproduce.

6. Development Strategies
Oviparity – laying eggs
Ovoviviparity – development of eggs inside the mother and the organisms are fully developed when hatched and born
Viviparity – organism develops inside the mother
Ovi- all birds, most reptiles, few mammals
Ovo- some fish, and a lot of reptiles; nourished by egg yolk when inside the egg
Vivi- all mammals; nourished by mother’s blood through umbilical cord

7. Fertilization Most fishes and amphibians have external fertilization
Reptiles and birds have internal fertilization and lay eggs
Shelled eggs of reptiles and birds are an important adaptation of vertebrates to life on land

8. Ovulation Periodic release of mature ovum from the ovary Estrous cycle
Period of sexual receptivity
Menstrual cycle
Human and ape females shed the inner lining of their uterus during menstruation

9. Monotremes, Marsupials, and Placental Mammals
Monotremes- incubate eggs in nest or specialized pouch. Young obtain milk from mother’s mammary glands by licking skin
Ex. Duck-billed platypus, Echidna
Marsupials- fetuses are incompletely developed at birth and finish development in a pouch in the mother’s skin
Ex. Kangaroo, Opossum
Placental- fetuses nourished by placenta and remain in the mother for a longer period of time
Ex. Humans

10. Male Reproductive System
Seminiferous tubules- sites of sperm production, developed in a male fetus about days after its conception
Leydig Cells- begin to secrete testosterone at about 9-10 weeks
Testosterone secretion during embryonic development converts different structures into male external genitalia
In the absence of testosterone, structures develop female external genitalia

11. Cell divisions leading to sperm
Spermatogonium cell divides by mitosis to produce two diploid cells
One of the two cells undergoes meiotic division to produce four haploid cells that will become sperm
The other cell remains as spermatogonium
Primary spermatocyte- Diploid daughter cell that begins meiosis
Secondary spermotocyte- Two haploid cells that are produced after the first meiotic division
Spermatids- Two haploid cells produced after spermotyocytes second meiotic division

12. Seminiferous tubules consist of spermatogonia, and supporting sertoli cells

13. Sperm Structure Consists of head, body, and flagellum, or tail
Head encloses a compact nucleus capped by an acrosome
Body and flagellum help with the sperm’s movement

14. Accessory Organs
Epididymis- long coiled tube where sperm are delivered after production. Sperm must remain here for at least 18 hours
Vas deferens- Long tube where sperm enter

15. Semen Complex mixture of fluids and sperm
Prostate gland- helps to make up about 30% of semen. In the gland, the ejaculatory duct merges with the urethra from the bladder
Urethra carries the semen out of the body

16. Two Columns of Erectile Tissue
Corpora Cavernosa- along the dorsal side
Corpus Spongiosum- along ventral side
In an erection, the erectile tissue becomes hard as it fills with blood

17. Hormones regulate male reproductive function
The production of sperm and the secretion of testosterone are controlled by a follicle stimulating hormone (FSH) and a leutinizing hormone (LH) from the anterior pituitary

18. Female Reproductive System
Ovaries develop much slower than testes
Ovaries contain microscopic structures called ovarian follicles
Each follicle contains a potential egg cell called a primary oocyte and smaller granulosa cells
Granulosa cells begin to secrete estrogen at puberty and stimulate menstrual cycling

19. Oocytes and Granulosa Cells

20. Ovarian Cycles has 3 Phases
Follicular phase- the primary oocyte completes the first meiotic division and produces one large daughter cell, the secondary oocyte, and one tiny daughter cell, a polar body
Ovulation- a released oocyte is propelled through the Fallopian tube toward the uterus. If not fertilized, the oocyte disintegrates within a day. If fertilized, the zygote takes about 3 days to reach the uterus and another 2-3 days to implant in the endometrium.
Luteal Phase- the corpus luteum is formed and secretes estrogen and progesterone, another steroid hormone. The two hormones exert negative feedback inhibition of FSH and LH. This acts as a natural contraceptive mechanism and prevents both the development of additional follicles and continued ovulation.

21. Secretory Phase and Menstrual Phase
During luteal phase, estrogen and progesterone cause the endometrium to become enriched with glycogen deposits, which is called the Secretory Phase. These changes prepare the uterine lining for embryo implantation.
Menstrual Phase- the corpus luteum degenerates which declines the blood concentration of estrogen and progesterone and onsets menstruation
If implantation occurs the embryo produces human chorionic gonadotropin (hCG), and it maintains the corpus luteum and prevents menstruation until the placenta takes over.

22. Contraception and Infertility Treatments
Methods of birth control are termed contraception
Abstinence
Condom
Diaphragm
Infertility- pregnancy is unable to occur due to a variety of reasons

23. Prevention of Ovulation
Birth control pills block ovulation and no ovum is available to be fertilized
Intrauterine device- is inserted and prevents implantation of an embryo because of the irritation it produces

24. Sterilization and Infertility
Sterilization is accomplished by the surgical removal of portions of the tubes that transport the gametes from the gonads. It can be performed for males and females.
Infertility in females can be caused from hormonal imbalance, lack of ovulation, blockage of Fallopian tubes, and age.
- Male infertility is usually due to a reduction in sperm number, viability, motility, hormonal imbalance, or damage to the vas deferens.
Hormone Treatment can induce ovulation or by the use of assisted reproductive technologies, such as in vitro fertilization and intracytoplasmic sperm injection.