Reproduction Quiz

Question 1

Testes

Answer 1

produce sperm (spermatogenesis inside structures called seminiferous tubules) and testosterone

Question 2

Epididymis

Answer 2

Maturation (motility) and storage of sperm cells

Question 3

Vas deferens/ Sperm duct

Answer 3

Carries mature sperm cells to seminal vesicle and prostate gland (arousal)

Question 4

Seminal vesicle

Answer 4

adds nutrient-filled fluids (fructose – for energy) and mucous (protection) to mature sperm cells (seminal vesicle secretions = 70% of fluid volume of semen)

Question 5

Prostate Gland

Answer 5

adds alkaline fluids (helps neutralize acidic environment of vagina so sperm can survive - prostate gland secretions = 30% of fluid volume of semen)

Question 6

Semen travels out of the body through the….

Answer 6

urethra inside the penis

Question 7

Ovaries

Answer 7

produce oocytes (they mature in the ovary during oogenesis prior to ovulation) and produces estrogen and progesterone

Question 8

Fimbriae

Answer 8

tissue adjacent to ovary that sweeps an “egg” into the fallopian tube

Question 9

Oviducts/ Fallopian tubes

Answer 9

tube that transports oocyte to uterus (where fertilization occurs as well)

Question 10

Uterus

Answer 10

location where fertilized egg will implant and develop

Question 11

Endometrium

Answer 11

Blood rich, mucous membrane lining the uterus to provide nutrients to implanting embryo

Question 12

Vagina

Answer 12

passageway for penis to deliver sperm to
uterus (note that a muscular opening called the cervix protects the uterus); passageway for birth from uterus

Question 13

Seminiferous Tubule

Answer 13

-Spermatogenesis (creation of male gametes) occurs in the testes in structures called seminiferous tubules
-Each tubule is surrounded by a membrane (basement membrane) which is lined with cells called germline epithelium cells (diploid)
-Germline epithelium cells divide by MITOSIS to make spermatogonia (which grow into primary spermatocytes (diploid cells) that divide by MEIOSIS to make spermatozoa)
-Sertoli cells in the tubules nourish developing spermatozoa
-Leydig cells (produce testosterone) and blood capillaries are found OUTSIDE/ surrounding the tubules

Question 14

Spermatogenesis Steps

Answer 14

1.Germline cells (in seminiferous tubules) divide by mitosis to produce spermatogonia (2n)
* - some return to basement membrane and some continue growth into primary spermatocytes (2n)
2.FSH (follicle-stimulating hormone) stimulates meiosis I in primary spermatocytes (producing haploid (n = 23) secondary spermatocytes)
3. LH (luteinizing hormone) stimulates Leydig cells in the testes to produce testosterone
4. Testosterone stimulates meiosis II in secondary spermatocytes (producing 4, haploid (n= 23) spermatids) and stimulates Sertoli cells
5. Spermatids differentiate into sperm with nourishment from -Sertoli cells (tails, midsections – mitochondria) and move into the interior portion of the seminiferous tubules (the lumen) to be transported to the epididymis (for storage and maturation – mobility/ swimming)

Question 15

Oogenesis (Pre-PHASE 1)

Answer 15

1. Germline cells in the ovaries divide by mitosis to produce oogonia (fetus)
2. Oogonia undergo growth to become primary oocytes (fetus)
3. Primary oocytes begin meiosis I, but are arrested at Prophase I until puberty
   * - Note: Primary oocytes are each surrounded by a layer of supporting cells called follicle cells. Primary oocytes + follicle cells = “primary follicles”

Question 16

Oogenesis PHASE 1: FOLLICULAR PHASE (Days 5-~14)

Answer 16

4. FSH (follicle-stimulating hormone) stimulates ONE primary oocyte (“follicle”) to mature and complete meiosis I (producing two haploid (n = 23) cells – one secondary oocyte and one polar body)
   * - Note: the division of the cytoplasm in meiosis in oocytes is UNEQUAL, resulting in one LARGE (largest cell in the human body by volume) secondary oocyte, and one small cell called a polar body (basically just a reservoir for the extra set of chromosomes – will later degenerate)
5. The secondary oocyte (“follicle”) secretes estrogen (to inhibit FSH - negative feedback - so only one follicle matures at a time, and to stimulate the lining of the uterus (endometrium) to “repair”/ grow and develop new tissues rich in blood vessels – to nourish an embryo if fertilization occurs)
6. Secondary oocytes begin meiosis II, but arrest at Prophase II/ Metaphase II. (Note: meiosis II will ONLY be completed IF the oocyte is fertilized by a sperm cell (this will produce another polar body and an ovum)

Question 17

Oogenesis PHASE 2: OVULATION (midway through the cycle, ~Day 14)

Answer 17

7. Rising levels of estrogen stimulate LH (luteinizing hormone) and some FSH (in lesser amounts) to be released in a “surge” from the anterior pituitary (positive feedback). This “surge” of LH stimulates ovulation of an “egg” (a secondary oocyte surrounded by an inner layer of follicle cells and a glycoprotein coat called the zona pellucida) from the ovary into the fallopian tube

Question 18

Oogenesis PHASE 3: LUTEAL PHASE (Days 14 - 28)

Answer 18

8. LH stimulates the ruptured follicle inside the ovary to develop into a structure called the corpus luteum
9. The corpus luteum secretes high levels of progesterone (and lower levels of estrogen). Progesterone thickens and maintains the highly vascular endometrium of uterus for 10-12 more days after ovulation in preparation for pregnancy.
10. High levels of both estrogen and progesterone in the bloodstream act as a negative feedback mechanism on the pituitary (no FSH and no LH = no more mature follicles produced during this time)

Question 19

Oogenesis PHASE 4: MENSTRUATION (Days 1-5)

Answer 19

11. If fertilization occurs, an embryo implants in the endometrium and secretes hormones to maintain the corpus luteum (and endometrial lining of the uterus)
12. If NO pregnancy, the corpus luteum degrades and levels of estrogen and progesterone drop

Question 20

FSH (follicle-stimulating hormone)

Answer 20

-Spermatogenesis: FSH stimulates meiosis I in primary spermatocytes (producing haploid (n = 23) secondary spermatocytes)
-Oogenesis: FSH stimulates follicular growth and stimulates estrogen secretion from follicles

Question 21

LH (luteinizing hormone)

Answer 21

-Spermatogenesis: LH stimulates Leydig cells in the testes to produce testosterone
-Oogenesis: LH surge causes ovulation and causes development of corpus luteum

Question 22

Testosterone

Answer 22

-Stimulates meiosis II in secondary spermatocytes (producing 4, haploid (n= 23) spermatids) and stimulates Sertoli cells
-Causes prenatal development of male genitalia, it aids in development of male secondary sex characteristics (body hair, deepening voice, muscle development etc.), and it helps to maintain libido (sexual drive)

Question 23

Role of Estrogen and Progesterone: Oogenesis

Answer 23

-Follicular phase of oogenesis: the secondary oocyte (“follicle”) secretes estrogen (to inhibit FSH - negative feedback - so only one follicle matures at a time, and to stimulate the endometrium to “repair”/ develop new tissues rich in blood vessels – to nourish an embryo if fertilization occurs)
-Ovulation phase of oogenesis: rising levels of estrogen stimulate LH and some FSH (in lesser amounts) to be released in a “surge” from the anterior pituitary (positive feedback). This “surge” of LH stimulates ovulation of an “egg”
-Luteal phase of oogenesis: high levels of both estrogen and progesterone in the bloodstream act as a negative feedback mechanism on the pituitary (no FSH and no LH = no more mature follicles produced during this time)
-Menstruation: without estrogen and progesterone, the endometrial lining cannot be maintained and it sloughs off (menstruation/ a woman’s period)

Question 24

Role of Estrogen and Progesterone: Developing Female Sex Characteristics

Answer 24

Estrogen and progesterone cause prenatal development of female reproductive organs, they aid in monthly development and ovulation of an egg and preparation of a woman’s body for pregnancy (post-puberty), and they aid in development of female secondary sex characteristics (breast development, body hair, fat deposition etc.)

Question 25

Role of Estrogen and Progesterone: Pregnancy

Answer 25

-Maintain the highly vascularized endometrium, thicken the cervix, and prevent FSH and LH from releasing more follicles) -Maintain the highly vascular endometrium and prevent release of FSH and LH from the anterior pituitary -Progesterone prevents uterine contractions by inhibiting oxytocin and causes development of breast tissue -Estrogen stimulates growth of uterine muscles and development of mammary glands (but it inhibits the milk producing cells from releasing milk - these are stimulated to grow by prolactin during pregnancy)

Question 26

Role of Estrogen and Progesterone: Parturition

Answer 26

-Extreme stretching of the uterine walls (baby takes up ALL space) triggers release of estrogen (estriol) from placenta -Estrogen increases sensitivity of uterine muscles to oxytocin and inhibits progesterone -Oxytocin released from pituitary (as progesterone levels drop, oxytocin release and contractions of uterine muscles no longer inhibited by progesterone) -Oxytocin targets cells of the uterus, causing muscles to contract (it also inhibits progesterone) -Oxytocin triggers lactation/ contraction of muscles in breast tissue (milk secretion/ breastfeeding); Prolactin no longer inhibited by estrogen, so triggers milk-producing cells to secrete milk

Question 27

Spermatogenesis Overview (for comparison with oogenesis)

Answer 27

-Location: Occurs entirely in testes -Meiotic divisions: Equal meiotic division of cells -Germline epithelium: Is involved in gamete production -Gamete number produced: Four -Size of gametes: Sperm are smaller than spermatocytes -Duration: Uninterrupted process -Onset: Begins at puberty -Release: Continuous -End: Lifelong (but reduces with age)

Question 28

Oogenesis Overview (for comparison with spermatogenesis)

Answer 28

-Location: Occurs mostly in ovaries -Meiotic divisions: Unequal division of cytoplasm -Germline epithelium: Is not involved in gamete production -Gamete number produced: One (plus 2 - 3 polar bodies) -Size of gametes: Ova larger than oocytes -Duration: In arrested stages -Onset: Begins in foetus (pre-natal) -Release: Monthly from puberty (menstrual cycle) -End: Terminates with menopause

Question 29

Genetic and Hormonal Control: Male

Answer 29

-In males, the 23rd pair = XY -The Y chromosome carries a gene called SRY (Sex Determining Region Y) which codes for a protein called TDF (testis-determining factor) -TDF causes the embryonic gonads to develop into testes (which produce testosterone).

Question 30

Genetic and Hormonal Control: Female

Answer 30

-In females, the 23rd pair - XX -No Y chromosome = no SRY = no TDF = embryonic gonads develop into ovaries (which produce estrogen and progesterone). -Estrogen and progesterone cause prenatal development of female reproductive organs, they aid in monthly development and ovulation of an egg and preparation of a woman’s body for pregnancy (post-puberty), and they aid in development of female secondary sex characteristics (breast development, body hair, fat deposition etc.)

Question 31

Hormones and Location of Secretion

Answer 31

-FSH is secreted from the Anterior Pituitary -Estrogen is secreted from the -Ovaries (developing follicle/ secondary oocyte in follicular phase and corpus luteum in luteal phase) -LH is secreted from the Anterior Pituitary -Progesterone is secreted from the Ovaries (corpus luteum)

Question 32

Oxytocin

Answer 32

-Oxytocin targets cells of the uterus, causing muscles to contract (it also inhibits progesterone so more oxytocin can be released) -Muscle contractions in the uterus stimulate more oxytocin to be released (causing more uterine contractions, causing more oxytocin to be released etc. – this is a POSITIVE feedback mechanism - it reinforces or AMPLIFIES the response/ change) -Oxytocin triggers lactation/ contraction of muscles in breast tissue (milk secretion/ breastfeeding) -Concentration gets higher as birth goes on

Question 33

Prostaglandins

Answer 33

-Fetus becomes increasingly cramped by contractions and releases prostaglandins, which stimulate more uterine contractions -Concentration gets higher in the midst of contractions

Question 34

Prolactin

Answer 34

-Prolactin stimulates milk producing cells to grow during pregnancy -Prolactin, once uninhibited by estrogen at the end of birth, triggers milk-producing cells to secrete milk

Question 35

Steps of Fertilization

Answer 35

1.Millions of sperm cells are ejaculated into female’s vagina (sexual intercourse) 2. Upon entering the female reproductive tract, biochemical changes occur to sperm in the final part of its maturation (capacitation) - chemicals in the uterus dissolve cholesterol coat around sperm (improves motility) and destabilize acrosome cap (for acrosome reaction once sperm meets egg) 3. Sperm travel (“swim”) from the vagina, through the cervix, up through the uterus and into the fallopian tubes (oviducts) where, hopefully, an “egg” will be waiting! FERTILIZATION OCCURS (usually) IN THE OVIDUCT!!! * * Note: Chemical signals from the egg (secondary oocyte) attract sperm toward it (chemotaxis) 4. Sperm cells that reach the egg begin working their way through (“digging into”) the follicle cells surrounding the “egg” (secondary oocyte) 5.Acrosome vesicles on sperm cells that penetrate the follicle cells bind to receptors on the zona pellucida of the “egg” and release hydrolytic enzymes from their acrosome to digest through it (acrosome reaction) 6. Once a sperm is through the zona pellucida, it binds to “docking proteins” on the egg membrane. Following this, the membranes of the sperm and “egg” fuse and the sperm nucleus (and centrioles) enters the egg. 7. Calcium ions are released in the egg, triggering the final meiotic division in the egg nucleus (and polar body creation) 8. Calcium ions (within milliseconds) also stimulate the cortical reaction (to prevent polyspermy – more than one sperm entering the egg) Vesicles (called cortical granules) are stored in the egg cytoplasm just inside the plasma membrane 9. Vesicles fuse with the plasma membrane 10. Vesicle fusion releases enzymes (exocytosis) that destroy the sperm-binding proteins on the “egg” plasma membrane and harden it (no more sperm shall bind/ pass!) – creates a “fertilization membrane/ envelope” 11. Within 24h, the two haploid (n) nucleii (sperm and egg) fuse, creating a one-celled zygote (fertilized egg) that is diploid (2n) – AKA, “Your eggo is preggo!”

Question 36

A fertilized egg is a.....

Answer 36

zygote

Question 37

In the 2-5 days post fertilization...

Answer 37

cells inside of it undergo rapid mitotic divisions to form a functional blastocyst that will implant in the endometrial lining of the uterus.

Question 38

What is the function of HCG?

Answer 38

Maintains the corpus luteum, which maintains high levels of estrogen and progesterone, maintaining the endometrium for implantation and embryo growth/ development

Question 39

Origin of HCG

Answer 39

Secreted by the embryo if fertilization occurs

Question 40

Structure of Placenta

Answer 40

-Disc-shaped structure (half fetal tissue, half mother’s tissue) that will nourish the embryo/ fetus and secrete hormones to maintain the pregnancy after the corpus luteum degrades -Placenta connects to the fetus through blood vessels in the umbilical cord -Umbilical vein delivers oxygen-rich, nutrient-rich (glucose, amino acids, water, vitamins, minerals, antibodies, lipids) blood to the fetus: this blood also contains hormones and it may contain viruses, alcohol/ drugs/ nicotine (depending on mom during pregnancy) -Pair of umbilical arteries carry carbon dioxide-rich blood (with urea, water, and hormones – like hCG) from the fetus to the placenta

Question 41

Function of the Placenta

Answer 41

-Nourishes the embryo/ fetus -Secretes estrogen and progesterone to maintain the pregnancy after the corpus luteum degrades

Question 42

Process of IVF

Answer 42

1. “Down Regulation” Using Drugs - Stop the natural menstrual cycle - these drugs prevent natural release of FSH (follicle stimulating hormone) and LH (luteinizing hormone) from the pituitary gland (which also stops the natural release of estrogen and progesterone) - process takes ~2 weeks (nasal spray) 2. “Superovulation” using FSH and hCG - High doses of follicle stimulating hormone administered through a series of injections (stimulates follicle development/ egg production). hCG then administered through a series of injections (matures follicles/ eggs). 2. Retrieval of Eggs - ultrasound to observe and eventually remove/ retrieve mature eggs through follicular aspiration (involves an outpatient operation and a VERY long aspiration needle - about as long as your arm!) 4. Sperm collection and processing * * Male provides sample while woman is undergoing retrieval * * Sperm is washed (removes debris, white blood cells, seminal proteins) * * Sperm is processed (removes dead/ degenerate/ immotile sperm - provides the best sperm for fertilization process) 5. Fertilization of Eggs (in one of two ways) - In vitro fertilization: Sperm is mixed with eggs in a petri dish and allowed to fertilize the eggs “naturally” (sperm and eggs are incubated together for 24h before fertilization success is assessed)