Reproduction

Question 1

Neuroendocrine control of reproduction:

Gonadotropin-releasing hormone (GnRH) (2)

what + who

Answer 1

• A decapeptide (10 amino acids) and is the key regulator of reproduction in vertebrates
• Was discovered by Andrew V. Schally and Roger Guillemin, both awarded 1977 Nobel prize in medicine

Question 2

Primary structure of GnRH

Answer 2

• The primary sequence of 24 diffGnRH molecular forms have been elucidated in different species
• Simlarity exists between sequences at N- and C- terminal regions

Question 3

GnRH is synthesized in —— and reaches —— via ——

Answer 3

• The neurosecretory neurons in hypothalamus
• anterior pituitary
• hypothalamohypophyseal portal system

Question 4

GnRH is released in a pulsatile manner to:

Answer 4

Stimulate release and synthesis of LH and FSH

Question 5

GnRH analoga are used to treat a number of clinical conditions including (8):

Answer 5

• precocious (advanced) and delayed puberty
• hypogonadism (diminished functional activity of the gonads—the testicles or the ovaries—that may result in diminished production of sex hormones)
• anovulation (not ovulating)
• amenorrhea (the absence of menstruation)
• premenstrual syndrome (disruptive set of emotional and physical symptoms that regularly occur in the one to two weeks before the start of each menstrual period)
• inadequate luteal function
• Endometriosis
• Hormone-dependent neoplasia (uncontrolled, abnormal growth of cells or tissues in the body)

Question 6

Neuroendocrine regulation

Effects of opiates (3):

what + estrogen + negative feedback

Answer 6

• opiates inhibit pulsatile release of GnRH
• Estrogen stimulates Kiss peptin and Kiss peptin stimulates GnRH
• The negative feedback effects of androgens on hypothalamus is to some extent through effect on opiates

Question 7

Effects of Gonadal steroids in female (4):

LH secretion + mediated by + ovulatory + inhibited

estrogen and progesterone

Answer 7

• Estrogen can increase LH secretion
• The effect of estrogen is mediated by increased production of Kiss peptins
• This is important to bring about the ovulatory surge of gonadotropins
• LH and FSH production are inhibited by combination of estrogen and progesterone

Question 8

Pregnancy pills are based on :

Answer 8

combination of estrogen and progestogens that inhibit ovulation

Question 9

In male, the effect of androgens are:

Answer 9

• primarily inhibitory: pulsatile release of GnRH and LH are inhibited by androgen surge

Question 10

Gonadal peptides

Inhibin and activin (4)

produced where + family + inhibin + activin

Answer 10

• Produced in both female ovary and male tetis and involved in specific regulation of FSH production
• Belong to the transforming growth factor-B (TGF-B) superfamily
• Inhibin inhibits secretion of FSH without effecting LH
• Activin stimulates secretion of FSH independent of GnRH in addition to other actions

Question 11

Ovarian development and oogenesis

During each ovarian cycle, a number of primordial follicle depart from —— and start rapid pattern of ——- growth ad development. Once at this stage, the follicle must achieve ovulation or become atretic. Most follicles undergo —– (degeneration that includes loss of the oocyte) and only a few reach the —–.

Answer 11

• the resting pool
• gonadotropin dependent
• astresia
• preovulatory Graafian follicle stage

Question 12

How does a primary follucle become a preovulatory (Graafian follicle) (3)?

Answer 12

Primary follicle
1. Theca and granulosa cells become more numerous and small spaces appears in the follicle. The structure forms the secondary follicle.
2. The spaces become filled with follicular fluid and enlarge to form a single large cavity, the antrum
3. The follicle enlarge to approximately 20-25 mm in diameter containing an oocyte of 120 um in diamter and become preovulatory (Graafian) follicle.

Question 13

According to the prevailing view of most investigators, female mammals produce all the egg cells—oocytes—they will ever have during their —–. A female’s total number of egg cells—a cru- cial factor for her fertility—is thus defined ——.

Answer 13

• fetal life
• at birth

Question 14

What occurs in the fetal ovaries and puberty for girls?

Answer 14

In the fetal ovaries, diploid germ cells called oogonia (haploid) divide repeatedly by mitosis to produce many oogonia. Each of these oogonia undergoes the very first stage of meiosis—during which its chromosomes replicate —during fetal life or shortly afterward. The cells are then called primary oocytes. Thereafter the cells remain as primary oocytes, without completing the first meiotic division, until they are ovulated following a female’s attainment of reproductive maturity at puberty. With each menstrual cycle, the primary oocye gets stimulated to go through maturation into mature follicle from resting pool. 10-15 every month, only 2-3 make it.

Question 15

After a female reaches sexual maturity, one or a few of the primary oocytes in her ovaries mature and undergo ovulation—release from the ovaries—during each of her ovulation cycles. Because all the primary oocytes are formed during —- life, some must remain in the ovaries, awaiting ovulation, for many years in long-lived mammals. An individual primary oocyte completes its first meiotic division at ——. It will complete its second meiotic division ——-

Answer 15

• fetal
• the time it is ovulated
• only if it is fertilized.

Question 16

One of the most important universal properties in mammalian reproduction is that ovulation always occurs in response to ——- from the —–

Answer 16

• a surge of luteinizing hormone (LH) released
• anterior pituitary gland

Question 17

Soon after a female is born, each primary oocyte in her ovaries becomes enclosed by a single layer of somatic cells. An oocyte and its layer of somatic cells are then together called a —-. After a female has reached reproductive maturity, a subset of her —— is recruited to mature further during each menstrual or estrous cycle—a process termed —–. The part of the menstrual or estrous cycle during which follicles mature is known as the —– of the cycle.

Answer 17

• primordial follicle
• primordial follicles
• folliculogenesis
• follicular phase

Question 18

Ultimately, when the follicular phase of the cycle ends with —–, the oocyte of this dominant follicle will ——; one of the daughter cells produced by this division will ——

Answer 18

• the LH surge
• complete its first meiotic division (a division that began when the female was a fetus in her mother’s uterus
• receive almost all the cytoplasm and will become the secondary oocyte that will be fertilized if mating is successful.

Question 19

When the follicle is fully developed, it is known as a mature, —— .

Answer 19

graafian/ preovulatory follicle

Question 20

Note that menstruation and estrus—the outward manifestations of menstrual and estrous cycles—occur at dramatically different times of the underlying physiological cycle; menstruation occurs —–, whereas estrus occurs —–

Answer 20

• roughly halfway between one ovulation and the next
• when ovulation occurs

Question 21

Although maturation to the secondary follicle stage requires ——, development to the primary follicle stage is —–

Answer 21

• follicle-stimulating hormone (FSH) and LH
• not believed to require hormonal support and therefore can occur without FSH and LH

Question 22

All the other follicles that initiated maturation at the start of the follicular phase—that is, all those except the single dominant one—degenerate by a process of programmed cell death termed —-. In species of mammals that normally give birth to litters of multiple offspring, atresia also occurs, but multiple follicles develop to full maturity and undergo ovulation.

Answer 22

• atresia

Question 23

What happens when the LH surge activates the process of ovulation?

Answer 23

Enzymes secreted by the fully mature follicle break down the thin layer of overlying ovarian epithelium and the juxtaposed follicular wall. Antral fluid pours out of the ruptured follicle into the space surrounding the ovary, carrying with it the oocyte surrounded by the zona pellucida and attached granulosa cells. Fertilization of an ovulated oocyte, if it occurs, normally takes place in the oviducts (also called the fallopian tubes). Each ovary is positioned near the opening of an oviduct, and oocytes released from the ovary are swept into the opening, as by ciliary action.

Question 24

In the ovary, ovulation marks the end of the —- phase and the start of the —- phase.

Answer 24

• follicular
• luteal

Question 25

Explain the lutea phase briefly:

preg + non preg

Answer 25

The cells of the ruptured mature follicle within the ovary reorganize through proliferation, vascularization, and other processes to form a structure called the corpus luteum (plural corpora lutea). If the oocyte in the oviduct is not fertilized, the corpus luteum— known as a corpus luteum of the cycle—secretes hormones for a finite time and then degenerates. In humans a corpus luteum of the cycle functions for about 10 days and then starts to regress; in the average cycle, the luteal phase ends on day 28, when the corpus luteum stops functioning entirely. If fertilization occurs, the corpus luteum—known as a corpus luteum of pregnancy—grows even further and continues to secrete hormones that are essential for establishing and maintaining pregnancy.

Question 26

Menstrual cycle is —– days in women and divided into two parts. How long is each?

Answer 26

• 25-30 days
• Follicular phase: 12-16 days
• Luteal phase: 10-16 days

Seperated by ovulation

Question 27

Follicular phase involves (2):

Answer 27

• Maturation of oocyte and ovulation

Question 28

The menstrual phase of the uterine cycle, lasting about 5 days, is the part when sloughing occurs. It is followed by the proliferative phase, during which the endometrium undergoes rapid thickening—from about 1 mm thick to 3–5 mm thick—and redevelops glands and circulatory vascularization. These uterine phases occur simultaneously with the —– in the ovaries. The uterine proliferative phase is synchronized to reach completion approximately when —–. The uterus then enters its secretory phase, which overlaps with the —– phase. In the secretory phase, the endometrium matures to the point that it is fully ready to accept implantation of an embryo and provide the embryo with nutritive support during its early postimplantation development. Implantation occurs about midway through the secretory phase if the egg that is ovulated is fertilized.

Answer 28

• follicular phase
• ovulation occurs
• ovarian luteal

Question 29

Two gonadotropic hormones (gonadotropins) secreted by the anterior pituitary gland play major roles in controlling menstrual and estrous cycles (3):

2 hormone + secretion conrtrolled by + how it works

Answer 29

• Luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
• The secretion of LH and FSH is controlled by gonadotropin-releasing hormone (gnRH), a neurohormone released by GnRH-secreting neuroendocrine cells in the hypothalamus of the brain, and by hormones—discussed later—secreted by the ovaries.
• The GnRH-secreting cells—which receive and integrate a variety of neural and neuroendocrine inputs—generate bursts of action potentials roughly every 1.5 h, and these bursts lead to synchronous release of GnRH by means of exocytosis. Accordingly, GnRH is secreted in pulses. The pulses of GnRH are carried by blood flow in the hypothalamo–hypophysial portal system to the anterior pituitary gland. There they stimulate the secretion of LH and FSH in pulses.

Question 30

Estrogen (principally estradiol) is synthesized and secreted by —–. Estrogen synthesis by
—–requires —— and entails cooperative function of the ——

Answer 30

• each such follicle
• a follicle
• both LH and FSH
• theca and granulosa cells.

Question 31

Kisspeptin neurons in the forebrain (4)

role + respond to + represent + act on by

Answer 31

• play critical roles in the control of the GnRH secreting cells.
• Because kisspeptin neurons have receptors for steroid hormones, they can respond to steroid (e.g., estrogen) signals
• Possibly represent the principal pathway by which the GnRH-secreting neurons are affected by steroid signals.
• Kisspeptin neurons act on the GnRH-secreting cells by secretion of kisspeptin, a peptide that acts—sometimes at exceedingly low concentrations—as an excitatory signal to the GnRH-secreting cells.

Question 32

Concentration of LH and FSH during ovulation and it’s effect (3).

Follicular + ovulation + effect

Answer 32

• During the follicular phase of the ovarian cycle, blood concentrations of LH and FSH remain relatively flat until a few days before ovulation.
• Then they increase dramatically, peaking at the time of ovulation. As the blood concentrations of LH and FSH rise, both hormones act on the follicles developing in the ovaries.
• The initial target of LH in each maturing follicle is the layer of theca cells that encloses the follicle. FSH acts on the granulosa cells. These two target tissues, working in concert, result in secretion of the steroid hormone estrogen by the follicles (we use the generic term estrogen for simplicity, although in fact two or more chemically specific estrogens are produced, the principal one being estradiol).

Question 33

The binding of FSH to granulosa
cell receptors stimulates:

Answer 33

the action of the enzyme aromatase, which converts the androgens into estrogen by a chemical process termed aromatization (see Figure 16.2). The granulosa and theca cells “need each other” to synthesize estrogen because only the theca cells can synthesize the androgens that are the precursors of estrogen, and only the granulosa cells can produce aromatase, which is required to convert androgens to estrogen.

Question 34

Concentration of Estrogen during ovulation and it’s effect (2).

follicular/ovul + mechanism

Answer 34

• Blood levels of estrogen increase slowly during the early stages of the follicular phase, then rise dramatically prior to ovulation.
• Estrogen itself plays a role in this increase by acting locally as a paracrine/autocrine agent within the ovary. In combination with FSH and growth factors, estrogen stimulates the proliferation of granulosa cells. This is a classic example of positive feedback in that estrogen produced by the granulosa cells stimulates mitotic multiplication of the granulosa cells themselves, and then as the cells increase in number, they produce increasing amounts of estrogen, a process that supports their continued proliferation.

Question 35

The granulosa cells of the developing follicles change in their ability to respond to LH as they mature:

Answer 35

Although they do not possess receptors for LH during the early part of follicular development, the granulosa cells of dominant follicles later produce LH receptors and incorporate them into their cell membranes. The LH receptors of the mature granulosa cells permit these cells to respond to the surge of LH that triggers ovulation.

Question 36

In addition to its effect on the anterior pituitary and hypo- thalamus, estrogen stimulates:

Answer 36

Growth of the endometrium of the uterus by binding with specific receptors in the endometrial cells. Indeed, the rise in blood levels of estrogen during the late part of the follicular phase in the ovary is responsible for the proliferative phase of the uterus (hyperplasisia = increase # and hypertrophy increase in size). Among its many effects, estrogen stimulates the endometrial cells to produce receptor molecules for progesterone, another steroid hormone, in preparation for events that occur after ovulation.

Question 37

Summarize the textbook diagram steps of: Hormonal control of estrogen produc- tion and secretion by an ovarian follicle (7)

Answer 37

Question 38

During the final part of the follicular phase, the —– of dominant follicles increase their secretion of —–, a hormone that inhibits —– secretion from the ——.

Answer 38

• granulosa cells
• inhibin
• FSH
• anterior pituitary

Question 39

For each below say where it is produced and what it does:

GnRH
LH
FSH
Androgens
Estrogen (principally estradiol)
Inhibin

Answer 39

Question 40

WHat does LH do at the surge of ovulation (3)?

induce oocyte + inc/dec/secrete .. lead to + transform

Answer 40

• When the anterior pituitary gland secretes LH in amounts sufficient to produce the surge in blood LH concentration , the LH exerts multiple effects on the granulosa cells of the dominant follicle (or follicles) that bring about dramatic events within hours. LH causes the granulosa cells to secrete chemical mediators that induce the oocyte to complete its first meiotic division.
• LH also causes the granulosa cells to begin secreting progesterone, decrease their secretion of estrogen, and release enzymes and prostaglandins that lead to breakdown of the outer follicular membranes and overlying ovarian epithelium.
• As the membranes and epithelium rupture, antral fluid and the oocyte are released from the ovary. Finally, LH initiates morphological and biochemical changes in the remaining granulosa cells and theca cells, causing them to transform into a corpus luteum.

Question 41

After the LH surge is over, the newly formed corpus luteum begins to function. At this time the anterior pituitary gland secretes a low level of ——, which maintains the corpus luteum. The corpus luteum secretes —– (which now becomes a major ovarian hormone), estrogen, and inhibin, and during the middle of the luteal phase, blood levels of these hormones ——–. —— is the major hormone secreted by the corpus luteum and rises to a particularly high blood concentration in the luteal phase. ——-, acting in concert, exert negative feedback on the anterior pituitary (and probably the hypothalamus) to keep ——-,—–,—– secretions low. Inhibin also suppresses FSH secretion.

Answer 41

• LH
• progesterone
• increase, peaking in association with maximum endometrial thickness
• Progesterone
• Progesterone and estrogen
• GnRH, LH, and FSH

Question 42

In primates, development of new follicles is greatly suppressed during the luteal phase, mediated in part by :

Answer 42

the low blood levels of LH and FSH that exist during that phase. In some other mammals, folliculogenesis can occur in all phases of the cycle but is reduced during the luteal phase.

Question 43

The corpus luteum is essential for establishing conditions that permit implantation and pregnancy. —- secreted by the corpus luteum in the luteal phase is especially important in preparing the uterus for implantation. The endometrial lining of the uterus is able to respond to —– at this time because of the process noted earlier, that ——. Stimulated by it, the exocrine glands of the endometrium secrete glycogen and enzymes, and additional blood vessels develop in the endometrium. The thickened and secretory endometrium is poised then to support implantation and nourishment of an embryo20 if fertilization occurs. Progesterone also ——-.

Answer 43

• Progesterone
• progesterone
• estrogen secreted in the follicular phase stimulated the endometrium to synthesize progesterone receptors
• inhibits contractions of smooth muscle cells in the walls of the uterus and oviducts

Question 44

The end of the luteal phase is that it sets the stage for a new cycle of folliculogenesis (i.e., the start of a new follicular phase):

Answer 44

Without a functional corpus luteum, blood concentrations of progesterone, estrogen, and inhibin decrease to the low levels that characterize the end of the luteal phase and the start of the follicular phase. The hypothalamus and anterior pituitary gland are thereby freed of negative feedback, so that secretion of LH and FSH can rise again, initiating another round of follicular development in the ovaries. Another important effect of the degeneration of the corpus luteum occurs in the uterus: The endometrium—because it is no longer supported by luteal hormones—is resorbed or, in species that menstruate, sloughed off.

Question 45

There are enzymatic expression change in corpus luteum:

Answer 45

• During follicular phase, it is predominatly estrogenic, in luteual phase it produces progesterone.

Question 46

Hormonal characteristic of luteal phase:

Answer 46

• higher levels of progesterone compared to follicullar phase which was predominatly estrogenic

Question 47

inhibin increases right before ovulation causing:

Answer 47

• Dip in FSH before it increases during ovulation again

Question 48

In the bgeining of follicular phase, FSH is —- and LH is —-. This is because —-

+ explain the chohort

Answer 48

• High
• Low
• Activin (higher FSH) which starts process of maturation of cohort from resting pool. Higher FSH receptor cohort respond to initial rise FSH. Ones with low, when there are dip in FSH goes through atresia where rest of them make to follicle.

Question 49

Why during ovulation you see a sudden rise in body temp in females?

Answer 49

• inflammatory response causes formation of fever

Question 50

Fertilization happens before it reaches

Answer 50

the uterus

Question 51

Estrogen and progesterone makes ednomerium layer ——. Also explain menstrual blood shedding:

Answer 51

• more vascularized
• contractile filaments can cause spasm that construct blood flow to cell, as long as progesterone levels are high it can prevent contractile filaments from contraction. When corpus luteum start to degenerate at end of luteal phase, there is a sudden decline in progesterone where it is no longer possible to prevent spasm. The spasm causes cell death and menstrual bleeding.

Question 52

Explain the steps of ooctye meisois (4)

Answer 52

• Meiosis start in the embruonic stages (when ovary is produced) but it does not go far to create haploid cells (end at prophase 1)
• Remains arrested until it becomes Graafin follicle
• Oocyte undergoes re-initation of meoisis because of ovulatory surge of gonadotropins (LH/FSH)
• Meiosis still does not go all the way (stops at metaphase 2) until it is fertilized

Question 53

When preganancy occurs what steps happen?:

Answer 53

1. Ovulated eggs goes follapian tube forms an embryo after finishing meiosis and attaches to the endometrium
2. The embryo start to break down endometrium layer to get nutrients
3. Cells in chorion (forms placenta) produces hormones. One of the hormone is chronic gonadotropins (LH like) produced in placenta. LH and FSH dips and chroinic gonadotropin sustains corpus luteum which supply progestrone so no spasm occurs.

Question 54

Morning afterpill (2)

what + mechanism

Answer 54

• Competitive antagonist for progesterone
• Once taken terminates pregancy since it distrupt progesterone from acting to prevent contractile filaments in endometrium

Question 55

intrauterine device

Answer 55

• prevents pregancy because once in uterus it cause inflammatory response and prevents implantation of embryo

Question 56

All steroid hormones are derived from —– and differ only in ——. They are also all —–

Answer 56

• cholesterol
• the ring structure and side chains attached to it
• lipid soluble

Question 57

Steroid hormones synthesis

Answer 57

• Sidechaine cleavage enzyme transfer cholesterol to pregnenolone (C21)
• 3 B-hydroxysteroid dehydrogenase transfer pregnenolone onto progesterone. Up to point, all happens in the gonads (testis/ovary) and adrenal cortex.
• In adrenal cortex progesterone gets converted to corticosteroids
• In gonads 17a-hydroxylase converts progesterone (C21) into 17a-hydroxyprogesterone (C21)
• C17,20-Lyase then converts this into adrogens: carbon gets cleaved off to form androstenedione (C19). Both male/female make this
• Androstenedieone is precursor to testosterone.
• Aromatase then converts androgens into estrogens. Androstenedione (C-19) becomes estrone (C18) and testosterone (C19) becomes Estradiol (C18)

Question 58

What are the 3 classes of steroids?

Answer 58

1. Progestrogenes (from progesterone in ovaries)
2. Estrogenes (2 types)
3. Androgenes (three types)

Question 59

Most of the circulating estrogen in female is:

Answer 59

Estradiol

Question 60

Explain how steroid hormone synthesis coreleates with follicule and luteal phase:

Answer 60

• In follicule phase we have more estrogen becuase of increase expression of the enzyme (aromatase, C17,20-Lyase, 17a-hydroxylase, it drives pathway to make androgen and to estrogen.
• In luteal phase, there is downregulation of some of this enzyme and aromatase level decrease and progesterone remain higher (not all transfered).

Question 61

General effects of estrogen (4):

primary + secondary + deposition + skin/feedb

Answer 61

• Enlargment and maintenance of the vagina, uterus, uterine tubes, ovareis and external repro organs (primary sexual reproduction system)
• Development of the breats (increase at follicular phase in collab with progesterone) and ductile system of the mammary glands (secondary sexual reproduction system)
• Increased deposition of adipose tissue in various subcutaneous layers, particularly the breast, thighs and buttlock (female physique)
• Influence skin texture and vascularization (menopause you get wrinkly), skeltal growth, hair distribution, electroylte balance, feedback action on pituitary and brain with kisspetin

Question 62

General effects of Progestogen (4):

endometriu + reduce + secrete + promote develop

Answer 62

• promotes secretatory changes in the endometrium, preparing uterus for implantation
• Reduce uterine contaraction and prevents expulsion of the implanated ovum
• Promotes secretion of nutrients in early luteal phase by cells linning the fallopian tube (fertilization happens at fallopian tubes)
• promotes development and secretion of alveolar tissue and general swelling tdue to secretory development in breast tissue

Question 63

2 main function of testis:

Answer 63

1. production of haploid sperm (spermatzoa)
2. Secretes hormones (steroid and peptide hormones=activin+inhibin)

Question 64

Opiate production and exercise:

Answer 64

• female athletes have fertility issues due to increase production of opiates which interferes. More exercise = more opiates

Question 65

Effects of Androgen:

In male, testosterone is a precursor for (2):

+ causes most of….

Answer 65

• Dihydrotestosterone (DHT) Only in male
• Causes most of the androgenic effect in males

Question 66

In males no cycle, they

Answer 66

constantly produce sperms (spermagensis)

Question 67

—– acts on CNS to increase sexual activity in both male and females

Answer 67

testosterone

Question 68

Anabolic steroids (2)

athletes + block

drugs made in a lab that mimic the naturally occurring male sex hormones called androgens

Answer 68

• abused often by athelete for phsique and can cause hormone dependent cancers. They build muscles
• Block gonadotropins

Question 69

Voice difference in male and female, and aggressive behaviour (CNS) is due to

Answer 69

androgen

Question 70

Menopause and germ cells:

Answer 70

• After conception, Germ cell proliferate, reach max of 7 million cell around 6 months
• By birth many Germ cells die and by puberty there is even less. At menopause you run out of germ cells and there is no follicules to make female hormones to support cycle and you have less sex drive.

Question 71

Male goes through andropause:

Answer 71

• Germ cell proliferate in testis through lufe, androgen drives it (spermatogenesis) peaks at early 20 and declines. STill enough for reproduction and masculinity