Reproduction and Development

Human Development

    The reproductive system makes it possible for organisms to pass on their genes to the next generation. There are many different ways to accomplish the task, but ultimately new individuals will develop and enter the world. In this section you will get a brief introduction to the different types of reproduction among animals. We will focus on the the reproductive anatomy of humans and our own development during the nine months in the womb.

The following questions will help you to review the material from the lecture, the laboratory, as well as the text.
  1. What is the overall goal and purpose of the reproductive system in animals?
  2. Define asexual reproduction.
  3. What are the advantages with asexual reproduction? Disadvantages?
  4. Briefly describe the processes of fission, budding and fragmentation and how these exemplify asexual reproduction?
  5. Define the process of parthenogenesis (use aphids and whiptail lizards as examples).
  6. What are the advantages with sexual reproduction? Disadvantages?
  7. Describe the generalized life cycle of an animal (e.g. mice).
  8. Explain the concept of hermaphroditism in animals.
  9. What is the difference between external and internal fertilization?
  10. Why is internal fertilization a dominant reproductive theme among terrestrial animals?
  11. Which two major reproductive strategies evolved among the reptiles in response to the challenging terrestrial environment?
  12. Define and explain the differences between ovoparity, ovoviviparity and viviparity among animals.
  13. Among many mammals the offspring is able to move and follow the parents within an hour of birth. Is there any connection between this observation and being viviparous?
  14. Describe the anatomy of the human male reproductive tract. Make a sketch. Label important structures. What is the function of these structures?
  15. The prostate gland is often a menace for many males. Why?
  16. Describe the structure of the testis and the epididymis. What are the function/s of these two structures?
  17. "Sperm cells are very specialized". True or false? Defend your choice.
  18. Describe the composition of semen. What is the origin and the role of the different components?
  19. When do human males start to produce sperms cells? When does the process stop in the life of a man?
  20. Describe the process of spermatogenesis in the seminiferous tubules.
  21. Describe the anatomy of the human female reproductive tract. Make a sketch. Label important structures. What is the function of these structures?
  22. What is the role/function of the uterus and the endometrium within the uterus?
  23. Describe the process that occurs in the ovaries of a female.
  24. What is the role of the hormones LH and estrogen in the process of ovulation? Where do these two hormones originate from?
  25. Why are egg cells often so much larger than sperm cells?
  26. For how long is an egg viable after ovulation (i.e. how long is the "window of opportunity" for fertilization)?
  27. Development can often be viewed in terms of the following sequence: gamete formation, fertilization, cleavage, gastrulation, organogenesis and growth. Briefly explain each component.
  28. Can "love" be viewed as a biological process? If so, what is its biological purpose? Why did it evolve?
  29. After intercourse: for how long are sperm cells viable?
  30. Where does fertilization occur?
  31. Briefly describe the process of fertilization. Can one single sperm cell fertilize an egg cell?
  32. What is a zygote? A blastula? A gastrula? An embryo? A fetus?
  33. How long does it take before the embryo implants in the endometrium? What is the purpose of the implantation event?
  34. Why is the first trimester of development such a critical period? What events occur during the last six months of gestation?
  35. What is the role of the placenta? From what tissue/cells does the placenta originate?
  36. Does gestation period among different mammalian species vary? Give a few examples.
  37. Labor is a "positive feedback" process. Explain.
  38. What is the role of the hormone oxytocin in the labor process?
  39. How does a woman know when labor has started?
  40. Is birth a painful process? Are there any remedies for such pain?
  41. What happens to the placenta after the baby is born?
  42. Why is it so important to try to nurse a baby just after it has been born?
  43. Do dolphins and whales nurse their young? Why?
  44. How does milk composition vary among different mammals? Can you explain the observed variation (use an example)?
  45. Summarize: Briefly describe the process of development from zygote to a mature baby in the human species.
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Lecture Outline
Function of the system
Passing the traits of the organism to the next generation
Asexual versus sexual reproduction

Asexual Reproduction
Individuals genetically identical
Only one “parent” is necessary
Works well in a stable environment
Examples of asexual reproduction

Sexual Reproduction
Promotes genetic diversity in the population
Two individuals are necessary
Role of meiosis in the production of gametes
How does meiosis generate genetic variation?
Connect to earlier lecture on cell division
Examples of different animal species
The Male Reproductive System
Reproduction in Humans

Male reproductive anatomy
Locate and know the function of: Testis, scrotum, epididymis, vas deferens, bulbourethral gland, seminal vesicles, prostate gland, urethra, erectile tissue in the penis, penis.
Structure of sperms cells (acrosome, nucleus, mitochondria, flagellum)
Males produce sperms cells on continuous basis from puberty to death
Role of seminiferous tubules in the testis.
Front View
Identify the above structures in this unlabeled drawing.

Female reproductive anatomy
Know the location and function of:  ovaries, oviducts (Fallopian tubes), uterus, cervix, vagina, labia, and the clitoris. (Front View).
The Female Reproductive System
All the egg cells in a female are formed in her ovaries during development (i.e. they are present (frozen in meiosis) at birth in contrast to males). These egg cells are activated one by one every month (with exceptions) from puberty to menopause (45-55yrs).

Role of Hormones
Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH) are produced by the pituitary gland in the brain
Progesterone and estrogen are produced by the ovaries and associated structures.
The ratio of these hormones control reproductive events in the females in a monthly cycle.
LH peaks during ovulation
The sharp drop in progesterone triggers menses.

What are the events that occur in the ovary each month in a reproductive non-pregnant female? In the uterus?

Role of the follicle
Corpus luteum

Examples of contraceptives
Fertilization between a sperm cell and an egg cell
Fertilization occurs in the oviduct
A human egg cell is receptive for about 24 hours
A human sperm cell is viable for about 72 hours (3 days)

After fertilization the combination of egg cell and sperm cell is referred to as a zygote.
Cell division is initiated as the zygote continues to move along in the oviduct.
Rapid cell division leads to a ball of cells referred to as a blastula.
The blastocyst will under the proper conditions implant into the uterine wall.
The first trimester is critical – during this time all the major organ systems are established. The new human being is referred to as an embryo.
The following two trimesters (the next six months) are focused on growth. The human being is referred to as a fetus.Human fetus in the womb
A 7-month old fetus is viable with the current medical technology.
Take a closer look at changes in the growing embryo/fetus as well as in the mother in these outstanding animations. Ultrasound can be used to evaluate the status of the growing fetus during development.
Birth occurs about 40 weeks after conception (about 9 months).
Vaginal delivery
Role of fontanels in the skull of the infant
Caesarean section (C-section)


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West Valley College
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Page created by: Peter Svensson
Updated: November 22  2010