Topic 11.4:  Sexual Reproduction

Essential Idea:   Sexual reproduction involves the development and fusion of haploid gametes.

At SHS, Topic 11.4 is taught in the following class unit(s):

• Reproductive Hormones (unit 49)
• Gametogenesis (unit 50)
• Pregnancy and Birth (unit 51)

Statements & Objectives:

11.4.U1  Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

• Define oogenesis and spermatogenesis.
• Outline the processes involved in spermatogenesis within the testes, including mitosis, cell growth, the two divisions of meiosis and cell differentiation
• Outline the processes involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of cytoplasm and the degeneration of polar body

11.4.U2  Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm.

• Compare the processes of spermatogenesis and oogenesis, including the number of gametes, size of games, the timing of formation and release of gametes.

11.4.U3  Fertilization in animals can be internal or external.

• Define polyspermy and explain why it is detrimental to an organism.
• Outline the process of fertilization.
• Describe mechanisms that prevent polyspermy.

11.4.U4  Fertilization involves mechanisms that prevent polyspermy.

• Compare internal and external fertilization.

11.4.U5  Implantation of the blastocysts in the endometrium is essential for the continuation of pregnancy.

• Define zygote, blastocyst and fetus
• Outline embryonic development from zygote to blastocyst.
• Draw a diagram of a blastocyst, labeling the inner cell mass.​

11.4.U6  HCG stimulates the ovary to secrete progesterone during early pregnancy.

• List the source, target and function of HCG.

11.4.U7  The placenta facilitates the exchange of materials between the mother and fetus.

• Describe the structure of the placenta, including the fetal villus, fetal capillary, maternal blood pool and chorion).
• Explain the benefits of having a high chorion surface area and a selectively permeable placental barrier.
• List the direction and mechanism of transport between maternal and fetal blood for CO2, O2, glucose, urea, antibodies and water in the placenta.

11.4.U8  Estrogen and progesterone are secreted by the placenta once it has formed.

• List the source, target and function of estrogen and progesterone as related to pregnancy.

 11.4.U9  Birth is mediated by positive feedback involving estrogen and oxytocin.

• List the source, target and function of estrogen and oxytocin as related to the birth process.

11.4.A1  The average 38-week pregnancy in humans can be positioned on a graph showing the correlation between animals’ size and development of the young at birth for other mammals.

• Analyze a graph to determine the relationship between gestation time and animal mass.
• Contrast altricial and precocial development mechanisms.

11.4.S1  Annotation of a diagram of seminiferous tubule and ovary to show the stages of gametogenesis.

• Label the following on a diagram of a seminiferous tubule:  interstitial cells, basement membrane, germinal epithelium cells, primary spermatocyte, secondary spermatocyte, Sertoli cells, spermatids, spermatozoa and spermatogonium.
• Label the following on a diagram of a ovary:  basement membrane, primary follicles, primary oocytes, developing follicles, secondary follicles, secondary oocycle, mature follicle, developing corpus luteum, corpus luteum, and degenerating corpus luteum.  

11.4.S2  Annotations of diagrams of mature sperm and egg to indicate functions.

• Label the following on a diagram of a mature sperm:  head, acrosome, plasma membrane, haploid nucleus, midpiece, helical mitochondria, microtubules, protein fibres in tail and tail.
• State the function of each of the following sperm structures:  head, acrosome, plasma membrane, haploid nucleus, midpiece, helical mitochondria, microtubules, protein fibres in tail and tail

• Label the following on a diagram of a mature egg:  haploid nucleus, centrioles, polar body, plasma membrane, corona radiata, zona pellucida, cortical granules and cytoplasm.
• State the function of each of the following egg structures:  haploid nucleus, centrioles, polar body, plasma membrane, corona radiata, zona pellucida, cortical granules and cytoplasm.

11.4.NOS  Assessing risks and benefits associated with scientific research-the risks to human male fertility were not adequately assessed before steroids related to progesterone and estrogen were released into the environment as a result of the use of female contraceptive pill.

• Outline how the female contraceptive pill prevents pregnancy.
• Describe problems attributed to estrogen pollution in water.

In the News:

• ​Scientists a step closer to mimicking way human body creates sperm (2018-12-01)
  
• Why humans develop sex cells as embryos — but corals don't (2016-12-20)
• ​Mothers and daughters: How starfish egg cells eliminate crucial structures to ensure the embryo will be viable (2016-03-21)
• Preventing sperm's 'power kick' could be key to unisex contraceptive (2016-03-17)
• Fertilized human egg emits microscopic flash of light (2016-04-27)
• Scientists find protein that unites sperm and egg (2014-04-16)
• How sperm get into the zona (2014-06-16)
• Embryo development: Some cells are more equal than others even at four-cell stage (2016-03-24)
• Human embryos grown in lab for longer than ever before (2016-05-04)
• Bacteria found in healthy placentas (2014-05-21)
• NIH gears up for a closer look at the human placenta (2014-06-02)
• Artificial womb for premature babies successful in animal trials (2017-04-25)
• Depression study examines levels of 'love' hormone and its impacts on mother-baby emotional bonding (2016-03-22)
• Estrogen in birth control pills has a negative impact on fish (2016-03-04)
• Unnoticed sex reversal in amphibians due to artificial estrogen from pills​ (2016-04-04)