Bio 32: Interruption of Reproduction

Are you ready to learn about the reproductive cycle? Great!! Remember to keep an eye out for Phil the Pill to find out how oral contraceptives interrupt this cycle. Let's begin.

Start here: Germ Cell Migration

Female Gameteogenesis

Male Gametogenesis

Ovulation

Egg Transport following Ovulation

Sperm Transport following Spermiogenesis

Sperm Transport within the Female Reproductive Tract

Fertilization

Visual Summary: Ovulation-Fertilization-Cleavage-Implantation

View Resources

Below are images showing the various stages of follicular development:

primordial follicle

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primary unilaminar follicle

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primary multilaminar (secondary) follicle

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Graafian follicle

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The ovum and its surrounding layers (the zona pellucida and the cumulus oophorus) are transported from the ovary to the uterine tube, captured by the tube's fingerlike projections (fimbriae). The granulosa and thecal cells of the follicle that remain in the ovary are now called the corpus luteum, which plays an important role in hormonal control and maintenance of the endometrium. Once in the uterine tube, the ovum (egg) is transported to the uterus by muscular contractions of the tubal wall. Tubal transport takes about 3-4 days. (Carlson, 1999)

Continue with Sperm Transport within the Female

See How Female Oral Contraceptives interrupt this process

Back to the Main Menu for Normal Reproduction

Spermatozoa are passively transported via testicular fluid from the seminiferous tubules of the testes to the head of the epididymis through fluid pressure, smooth muscle contractions, and ciliary movements. For roughly 12 days spermatozoa undergo biochemical maturation within the duct of the epididymis. The spermatozoa are now capable of fertilizing an egg.

Upon ejaculation, spermatozoa mix with two fluid secretions (one from the seminal vesicles and one from the prostate gland) as they pass through the ductus deferens. Semen exits the body through the urethra of the penis, typically consisting of 40-250 million spermatozoa and having a pH between 7.2-7.8. (Carlson, 1999) (Sherwood, 2001)

Continue with Sperm Transport within the Female

Back to the Main Menu for Normal Reproduction

In the female, sperm transport begins in the upper vagina where seminal fluid is deposited during copulation. The seminal fluid surrounding the spermatozoa acts as a buffer zone, protecting the spermatozoa from the acidity of the upper vagina. The short-lasting buffering effect creates enough time for the spermatozoa to approach the cervix (the lower outlet of the uterus). An increase in water content of the cervix around the time of ovulation enables sperm transport.

Within the cervix, there are two modes of sperm transport. Rapid transport is conducted by muscular contractions of the female reproductive tract. Slow transport results from spermatozoa using their flagella tails to swim. The outcome of this transport is entry of the spermatozoa to the inside of the uterine tube.

Capacitation of spermatozoa occurs as the spermatozoa are transported through the female reproductive tract and their surface glycoproteins are altered. The uterine tube muscles contract and simultaneously transport the egg down the tube and the spermatozoa up the tube (wow!). Sperm transport is complete when the spermatozoa contact the ovulated egg in the ampulla of the uterine tube. (Carlson, 1999) (Sherwood, 2001)

Continue to Fertilization

See How Male Contraceptive Methods can Influence Spermatogenesis and Sperm Transport

Back to the Main Menu for Normal Reproduction

Fertilization: the process whereby (typically) two gametes, an ovum and a spermatozoon, fuse together to form a zygote

Carlson, Bruce M. Human Embryology & Developmental Biology. Mosby, Inc. 1999: pp. 2-32.

Cohen, Hillary. "Follicular Development." http://sprojects.mmi.mcgill.ca/menstrualcycle/folliculardevelopmentpage.html.

Delves, P., Lund t., and Roitt I. 2002. "Future Prospects for Vaccines to Control Fertility." In HMS Beagle: The BioMedNet Magazine.
(http://www.biomednet.com/hmsbeagle/120/notes/feature)

Drill, Victor. Oral Contraceptives. McGraw-Hill Book Company, 1966. pp. 1-7, 15-29, 53-54, 59-62

Elizabeth, Pamela (interview). Director of Education, Planned Parenthood of Rhode Island. April 1, 2002.

Family Health International. "Contraceptive Update: Experimental Male Methods Inhibit Sperm," FHI's Quarterly Health Bulletin Network: Spring 1998, Vol. 18, No. 3.

Gard, David. "A summary of oogenesis in Xenopus laevis." May 1999. http://froglab.biology.utah.edu/Oogenesis.html.

Goldzieher, J., Rice-Wray, E. Oral Contraception Mechanism and Management. Charles C Thomas Publisher, 1966. pp. 1-7, 13-18,80-87

Gorman, Christine. "Who Needs a Period?" In TIME Magazine, September 18, 2002.

http://abcnews.go.com/sections/living/Healthology/morning_after010719.html#

http://pregnancy.about.com/library/blweek7.htm

http://www.abortionaccess.org/AAP/publica_resources/fact_sheets/mifepristone.htm

http://www.babycenter.com/refcap/pregnancy/fetaldevelopment/803.html

http://www.conrad.org/

http://www.drkoop.com/conditions/ency/article/001946.htm

http://www.earlyoptionpill.com/how.php3

http://ec.princeton.edu/info/ecp.html

http://www.emergencybirthcontrol.org/content_howEBCworks.htm

http://www.malecontraceptives.org

http://www.nhcqa.org/gallery.html

http://www.pharmacology2000.com/Endocrine/Gonadal/gonad6.htm

http://www.priestsforlife.org/resources/abortionimages/fig20baby7.jpg

http://www.reproline.jhu.edu/english/lfp/1advances/conrad_men.htm

http://www.standupgirl.com/inside/index.html

http://www.ultranet.com/~jkimball/BiologyPages.html

http://www.w-cpc.org/fetal1.html

http://www2.health-center.com/family/pregnancy/fetal_developm/week7.htm

Huskey, Robert J. "Germ cell migration." April 25, 1997. http://www.people.virginia.edu/~rjh/gondev.html.

Lissner, Elaine A. "Frontiers in Nonhormonal Male Contraception: A Call For Research," from http://www.malecontraceptives.org. March 8, 1994.

Mears, Eleanor. Handbook on Oral Contraception. Little, Brown & Company, Boston 1965. pp. 22-23,31-50.

Schulman, Audry. "Too much to swallow?" Boston Phoenix. April 13-20, 2002.

Sherwood, Lauralee. Human Physiology: From Cells to Systems. Brooks/Cole. 2001: pp. 715-751.

Snyder, Jeanne M. "Medical Cell Biology 2001: Fertilization and Implantation." http://www.medicine.uiowa.edu/ocrme/demo_curr/cell_biology_2001/lectures_2001/0101_fet_implnt_js.htm.

Spence, Alexander P. and Mason, Elliot B. Human Anatomy and Physiology. Benjamin/Cummings Publishing Company, Inc. 1987. pp. 810-833.

Ownby, Charlotte. "Histology: The Male Reproductive System." Nov. 2001. http://handin.cvm.okstate.edu/histology/

Turzillo, Adele. "Male Reproduction." http://www.physiol.arizona.edu/PSI467/notes/9.pdf.

Back to the Main Menu for Normal Reproduction


	Are you ready to learn about the reproductive cycle? Great!! Remember to keep an eye out for Phil the Pill to find out how oral contraceptives interrupt this cycle. Let's begin. Start here: Germ Cell Migration Female Gameteogenesis Male Gametogenesis Ovulation Egg Transport following Ovulation Sperm Transport following Spermiogenesis Sperm Transport within the Female Reproductive Tract Fertilization Visual Summary: Ovulation-Fertilization-Cleavage-Implantation View Resources		( Sherwood,2001) A human fetus surrounded by the amniotic sac




	( Huskey) (http://www.people.virginia.edu/~rjh/gondev.html)		Germ Cell Migration: Humans are sexually reproducing organisms that develop from the fusion of an egg and sperm cell. These gametes arise from primordial germ cells within the developing gonads (either ovaries or testes). Germ cells originate in the yolk sac of the embryo and migrate to the developing gonads, where they eventually give rise to female or male gametes by gametogenesis (oogenesis in females, or spermatogenesis in males). (http://www.people.virginia.edu/~rjh/gondev.html) continue here: Oogenesis Spermatogenesis Back to the Main Menu for Normal Reproduction


	( Spence, 1987).	Oogenesis: Female Gametogenesis
	(Carlson, 1999)	Female gametogenesis takes place within the ovaries of the developing embryo. Oogonia are the mitotically active female germ cells. By about the 5th month of pregnancy, these germ cells reach a maximum number. At this time, gamete proliferation is complete within the female. Primary oocytes are oogonia in the late fetal period that begin to undergo meiosis. A primordial follicle consists of a primary oocyte that is surrounded by a layer of granulosa cells. In the early months after birth, primary oocytes are halted in the diplotene stage (of prophase I) of meiosis I and remain arrested there until puberty. Stimulated by LH, the primary oocyte inside the growing follicle completes the first meiotic division shortly before ovulation (The first polar body is released.). The secondary oocyte further develops and then begins the second meiotic division. The Graafian follicle consists of the secondary oocyte and two layers of growing granulosa cells, a thin outer layer known as the zona pellucida and an inner layer called the corona radiata. As the secondary oocyte continues the second meiotic division, it is arrested in metaphase II. Stimulated by a surge of LH, the outer follicular wall ruptures. The ovum (previously the secondary oocyte) is released and is transported from the ovary to the uterine tube. If a spermatozoon fertilizes the ovum, the second meiotic division completes. A fertilized ovum and second polar body result. Ovulation consists of the rupturing of the outer follicular wall and the release of the ovum. (Carlson, 1999).


	(Spence, 1987)	Spermatogenesis: Male Gametogenesis
( Spence, 1987)	(Sherwood, 2001)	Spermatogenesis takes place in the seminiferous tubules of the testes in males. Spermatogonia are the mitotically active germ cells. In contrast to females, these germ cells remain in the mitotic cycle throughout the male's reproductive life. When spermatogonia cross the blood testis barrier, they are called primary spermatocytes. In contrast to females, meiosis of the primary spermatocytes does not begin until after puberty. During puberty, these spermatocytes undergo the first meiotic division, giving rise to secondary spermatocytes. This first division takes approximately 24 days. Secondary spermatocytes immediately enter the second meiotic division. This division, which takes approximately 8 hours, results in haploid spermatids. Through a process known as spermiogenesis, the immature spermatids become highly specialized spermatozoa. The nucleus decreases in size as the chromatin condenses, the Golgi apparatus gives rise to the acrosome, and a flagellum grows out from the main body, eventually forming a tail. All these changes are in preparation for fertilization. (Carlson, 1999) (http://www.physiol.arizona.edu/PSI467/notes/9.pdf.) Continue with Sperm Transport Back to the Main Menu for Normal Reproduction

	Egg Transport	Following Ovulation
The ovum and its surrounding layers (the zona pellucida and the cumulus oophorus) are transported from the ovary to the uterine tube, captured by the tube's fingerlike projections (fimbriae). The granulosa and thecal cells of the follicle that remain in the ovary are now called the corpus luteum, which plays an important role in hormonal control and maintenance of the endometrium. Once in the uterine tube, the ovum (egg) is transported to the uterus by muscular contractions of the tubal wall. Tubal transport takes about 3-4 days. (Carlson, 1999) Continue with Sperm Transport within the Female See How Female Oral Contraceptives interrupt this process Back to the Main Menu for Normal Reproduction		(Sherwood, 2001)	until

	Sperm Transport	Following Spermiogenesis
Spermatozoa are passively transported via testicular fluid from the seminiferous tubules of the testes to the head of the epididymis through fluid pressure, smooth muscle contractions, and ciliary movements. For roughly 12 days spermatozoa undergo biochemical maturation within the duct of the epididymis. The spermatozoa are now capable of fertilizing an egg. Upon ejaculation, spermatozoa mix with two fluid secretions (one from the seminal vesicles and one from the prostate gland) as they pass through the ductus deferens. Semen exits the body through the urethra of the penis, typically consisting of 40-250 million spermatozoa and having a pH between 7.2-7.8. (Carlson, 1999) (Sherwood, 2001) Continue with Sperm Transport within the Female Back to the Main Menu for Normal Reproduction		(Sherwood, 2001)	until

	Sperm Transport	within the Female
In the female, sperm transport begins in the upper vagina where seminal fluid is deposited during copulation. The seminal fluid surrounding the spermatozoa acts as a buffer zone, protecting the spermatozoa from the acidity of the upper vagina. The short-lasting buffering effect creates enough time for the spermatozoa to approach the cervix (the lower outlet of the uterus). An increase in water content of the cervix around the time of ovulation enables sperm transport. Within the cervix, there are two modes of sperm transport. Rapid transport is conducted by muscular contractions of the female reproductive tract. Slow transport results from spermatozoa using their flagella tails to swim. The outcome of this transport is entry of the spermatozoa to the inside of the uterine tube. Capacitation of spermatozoa occurs as the spermatozoa are transported through the female reproductive tract and their surface glycoproteins are altered. The uterine tube muscles contract and simultaneously transport the egg down the tube and the spermatozoa up the tube (wow!). Sperm transport is complete when the spermatozoa contact the ovulated egg in the ampulla of the uterine tube. (Carlson, 1999) (Sherwood, 2001) Continue to Fertilization See How Male Contraceptive Methods can Influence Spermatogenesis and Sperm Transport Back to the Main Menu for Normal Reproduction		(Sherwood, 2001)	until


	Within the Uterine Tube: Ovulation-Fertilization-Cleavage-Implantation
( Sherwood,2001) Begin Male Gametogenesis Back to the Main Menu for Normal Reproduction




Resources:
Carlson, Bruce M. Human Embryology & Developmental Biology. Mosby, Inc. 1999: pp. 2-32. Cohen, Hillary. "Follicular Development." http://sprojects.mmi.mcgill.ca/menstrualcycle/folliculardevelopmentpage.html. Delves, P., Lund t., and Roitt I. 2002. "Future Prospects for Vaccines to Control Fertility." In HMS Beagle: The BioMedNet Magazine. (http://www.biomednet.com/hmsbeagle/120/notes/feature) Drill, Victor. Oral Contraceptives. McGraw-Hill Book Company, 1966. pp. 1-7, 15-29, 53-54, 59-62 Elizabeth, Pamela (interview). Director of Education, Planned Parenthood of Rhode Island. April 1, 2002. Family Health International. "Contraceptive Update: Experimental Male Methods Inhibit Sperm," FHI's Quarterly Health Bulletin Network: Spring 1998, Vol. 18, No. 3. Gard, David. "A summary of oogenesis in Xenopus laevis." May 1999. http://froglab.biology.utah.edu/Oogenesis.html. Goldzieher, J., Rice-Wray, E. Oral Contraception Mechanism and Management. Charles C Thomas Publisher, 1966. pp. 1-7, 13-18,80-87 Gorman, Christine. "Who Needs a Period?" In TIME Magazine, September 18, 2002. http://abcnews.go.com/sections/living/Healthology/morning_after010719.html# http://pregnancy.about.com/library/blweek7.htm http://www.abortionaccess.org/AAP/publica_resources/fact_sheets/mifepristone.htm http://www.babycenter.com/refcap/pregnancy/fetaldevelopment/803.html http://www.conrad.org/ http://www.drkoop.com/conditions/ency/article/001946.htm http://www.earlyoptionpill.com/how.php3 http://ec.princeton.edu/info/ecp.html http://www.emergencybirthcontrol.org/content_howEBCworks.htm http://www.malecontraceptives.org http://www.nhcqa.org/gallery.html http://www.pharmacology2000.com/Endocrine/Gonadal/gonad6.htm http://www.priestsforlife.org/resources/abortionimages/fig20baby7.jpg http://www.reproline.jhu.edu/english/lfp/1advances/conrad_men.htm http://www.standupgirl.com/inside/index.html http://www.ultranet.com/~jkimball/BiologyPages.html http://www.w-cpc.org/fetal1.html http://www2.health-center.com/family/pregnancy/fetal_developm/week7.htm Huskey, Robert J. "Germ cell migration." April 25, 1997. http://www.people.virginia.edu/~rjh/gondev.html. Lissner, Elaine A. "Frontiers in Nonhormonal Male Contraception: A Call For Research," from http://www.malecontraceptives.org. March 8, 1994. Mears, Eleanor. Handbook on Oral Contraception. Little, Brown & Company, Boston 1965. pp. 22-23,31-50. Schulman, Audry. "Too much to swallow?" Boston Phoenix. April 13-20, 2002. Sherwood, Lauralee. Human Physiology: From Cells to Systems. Brooks/Cole. 2001: pp. 715-751. Snyder, Jeanne M. "Medical Cell Biology 2001: Fertilization and Implantation." http://www.medicine.uiowa.edu/ocrme/demo_curr/cell_biology_2001/lectures_2001/0101_fet_implnt_js.htm. Spence, Alexander P. and Mason, Elliot B. Human Anatomy and Physiology. Benjamin/Cummings Publishing Company, Inc. 1987. pp. 810-833. Ownby, Charlotte. "Histology: The Male Reproductive System." Nov. 2001. http://handin.cvm.okstate.edu/histology/ Turzillo, Adele. "Male Reproduction." http://www.physiol.arizona.edu/PSI467/notes/9.pdf. Back to the Main Menu for Normal Reproduction		until