1. Please feel free to chat amongst yourselves until we begin at the top of the hour. 1

2. Seminar Agenda The Reproductive System Questions & Answers 2

3. Unit 3-5 Project: Histology NOTE: Topic Choice, Outline and List of References are due at the end of Unit 3: 25 points Complete Paper (Part 1; Histology) due at the end of Unit 5: 50 points

4. Unit 3-5 Project: Histology Topic Proposal: Include a title page containing the title of the paper, your name and course details. Body of the project should begin on page 2. The references should start on a new page at the end of the essay. At least 3 references other than your book should be used. For information on APA reference style please go to the Kaplan Writing Center or the following websites: APA Research Style Crib Sheet: http://www3.wooster.edu/psychology/apa- crib.html#Intext Psychology With Style: http://www.uwsp.edu/PSYCH/apa4b.htm Avoid extensive quotes, unless there is absolutely no way to say it any better. Almost always you should be able to put things in your own words. Beware of plagiarism! The paper should be 4-7 pages long, including the reference page but excluding the title page. It is due no later than the end of Unit 5.

5. Questions 5

6. Embryology -terminology

7. Gametogenesis Human development begins at fertilization Male gamete (sperm) and female gamete (oocyte) come together and form a single cell or zygote. Sperm and oocytes contain half the number of chromosomes (haploid number) than present in somatic (body) cells. Gametogenesis is the process of formation and the development of specialized generative cells called gametes.

8. The stages of meiosis I and II Interphase Prophase IMetaphase IAnaphase I Telophase I Prophase IIMetaphase II Anaphase IITelophase II Let’s first label each stage. (and cytokinesis)

9. The Stages of Meiosis I Interphase The chromosomes replicate. It is similar to chromosome replication of mitosis. Two identical sister chromatids are held together by a centromere. Prophase I Chromosomes shorten and thicken. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. There are 4 chromatids in a tetrad. Metaphase I Tetrads line up at the center of the cell. Anaphase I The tetrads break apart and the pairs move to opposite sides of the cell. Sister chromatids remain attached at their centromeres.

10. The Stages of Meiosis II Telophase I Prophase II Metaphase IIAnaphase II (and cytokinesis) The cell separates into two cells. Telophase II (and cytokinesis) Meiosis I results in 2 haploid (1N) daughter cells Each daughter cell has half the number of chromosomes as the original cell. The pairs of sister chromatids start toward the center. Pairs of sister chromatids line up at the center. The pairs of sister chromatids separate and move to opposite sides of the cell. Results in 4 new cells that are 1N.

11. The Importance of Meiosis 1 (2N) cell -------> 4 (1N) cells The chromosome number of the egg and sperm is cut in half to insure that the zygote will have the proper number of chromosomes.

12. “Crossing Over” During Meiosis During ________, each pair of chromatids lines up next to its _________. prophase I homologue homologous chromosomes This pairing of homologous chromosomes produces _______. tetrads tetrad A tetrad consists of ___________. 4 chromatids It is possible for the chromatids within a homologous pair to twist around one another. Portions of the chromatids may break off and attach to adjacent chromatids. This process is called “____________” crossing over “Crossing over” is the exchange of genetic information (genes) between segments of homologous chromosomes during meiosis.

13. Gamete Formation Meiosis produces four haploid cells that are different. In males, meiosis results in 4 sperm cells. In females, 4 cells are produced, but only one will become an egg cell. All of the cytoplasm and all of the organelles are put into one egg cell. The other three cells will never be functional.

14. Mitosis occurs in all cells of the _____ except _____________. Meiosis only occurs in the formation of _____________. bodyegg and sperm

15. Haploid, 2N Haploid, 1N Diploid, 2N

16. Spermiogenesis

17. Oogenesis: Prenatal Maturation of Oocytes Oogonia are transformed into mature oocytes. Maturation process begins before birth and is completed after puberty. Oogonia - immature ovum - proliferate during early fetal life - oogonia enlarge to form primary oocytes before birth Primary oocyte - connective tissue cells surround it and form a single layer of flattened, follicular epithelial – primordial follicle - zona pellucida forms – amorphous glycoprotein material that surrounds the primary oocyte - begin the first meiotic division before birth, but completion of prophase does not occur until adolescence - follicular cells secrete oocyte maturation inhibitor which keeps the meiotic process arrested

18. Oogenesis: Postnatal Maturation of Oocytes During puberty, one follicle matures each month and ovulation occurs Long duration of the first meiotic division of up to 45 years may account in part for the relatively high frequency of meiotic errors in older females Nondisjunction – failure of paired chromatids to dissociate Primary oocyte in suspended prophase is vulnerable to environmental effects No primary oocytes form after birth in females Follicle maturation – primary oocyte increases in size and before ovulation completes the first meiotic division resulting in a secondary oocyte and first polar body Polar body – small dysfunction cell that degenerates

19. Oogenesis:Postnatal Maturation of Oocytes (cont’d) At ovulation – Secondary oocyte begins second meiotic division, but progresses only to metaphase when division is arrested Sperm penetration results in the completion of the second meiotic division Results in fertilized oocyte and second polar body There are approximately two million primary oocytes in the ovaries of newborn female Most regress during childhood Adolescence only have 40,000 primary oocytes Only 400 become secondary oocytes and are expelled at ovulation during reproduction

20. Oogenesis

21. Male and female gametes

22. Abnormal Gametogenesis: chromosomal abnormalities

23. Nondisjunction

24. Trisomy 21

25. Uterus Uterus has three layers: Perimetrium Myometrium Endometrium The functional layer of the endometrium is sloughed off during menstration

26. Ovarian cycle: Follicle-stimulating hormone (FSH) stimulates the development of ovarian follicles and the production of estrogen by the follicular cells Leuteinizing hormone (LH) serves as the “trigger” for ovulation (release of secondary oocyte) and stimulates the follicular cells and the corpus luteum to produce progesterone

27. Female Reproductive System 27 Ovaries Form in a fetus under influence of X chromosome Primordial germ cells, called oocytes, in outermost cortical region of ovary Primordial follicle = small oocyte enclosed in a single layer of simple squamous cells derived from the surrounding ovarian connective tissue (stroma) Cortical region has a layer of dense connective tissue called tunica albuginea and a layer of epithelium called the germinal epithelium At puberty, oocytes and follicles enlarge due to the expression of gonadotropins Small number develop into primary follicles

28. Primary oocyte in a secondary follicle

29. Primordial follicle (left) and secondary follicle (right)

30. Ovulation

31. Hormones during menstrual cycle

32. Fertilization

34. Blastocyst formation

35. Attachment of the blastocyst to the endometrial epithelium

36. First week

37. Questions 37