Reproduction 1

Question 1

Presence of the Y chromosome leads to male gonad development due to the presence of what gene? The non-functional X chromosome condenses to form nuclear mass known as what in females?

Answer 1

SRY gene

Barr body- lyonisation

Question 2

Both female and male gonads are derived from what? Up until what week are primordial gonads are undifferentiated? The undifferentiated reproductive tract includes what?

Answer 2

The urogenital ridge
6th week
A double genital duct system: Wolffian ducts, Mullerian ducts

Question 3

What ducts persist and regress in the male? The Sertoli cells of the testes produce what protein hormone? What gene induces the expression of MIF? Testosterone from Leydig cells causes what to happen?

Answer 3

Wolffian ducts persist and Mullerian ducts regress
Mullerian-inhibiting factor- MIF
SRY gene–> Mullerian duct degenerates
Wolffian duct–> epididymis, vas deferens, ejaculatory ducts and seminal vesicles

Question 4

Externally, under the influence of what does the penis form and tissue near it fuse to form the scrotum? What does testosterone also stimulate?

Answer 4

Dihydrotestosterone (DHT) produced from testosterone

The testes to descend into the scrotum

Question 5

In the female, the Mullerian system develops into what? What structure does not play a role in developmental processes? What are germ cells? Where do they originate from?

Answer 5

Fallopian tubes and a uterus
The ovaries
Specialised that develop into sperm and ova
The yolk sac of the hind gut

Question 6

When does mitosis in germ cells occur in males? In females?

Answer 6

Some in embryonic testes to form primary spermatocytes present at birth- begins during male puberty and continues throughout birth
During fetal development–> primary oocytes

Question 7

What are the results of the first meiotic divisions in males? In females? The second cell is what in females?

Answer 7

Secondary spermatocytes
Secondary oocyte
The first polar body which has no function

Question 8

When does the second meiotic division occur in males? In females? This results in what?

Answer 8

Continuously after puberty with spermatids and mature sperm cells produced
Not until after fertilisation of secondary oocyte by a sperm
A zygote and the second polar body which also has no function

Question 9

What is semen? % which is seminal vesicle fluid, prostatic and sperm? Included in prostate and seminal vesicle secretions?

Answer 9

Fluid and sperm cells together
60% seminal vesicle fluid, 30% prostatic and 10% sperm
Buffers to protect sperm against acidic vaginal secretions, chemicals to increase sperm motility e.g. fructose, prostaglandins to stimulate female peristaltic contractions

Question 10

Mnemonic to remember path of sperm to outside?

Answer 10

SREEVEN UP
Seminiferous tubules, rete testis, efferent ducts, epididymis, vas deferens, ejaculatory duct, nothing, urethra, penile urethra.

Question 11

What is each seminiferous tubule bounded by? How are Sertoli cells located in the testes?

Answer 11

A basement membrane

Each extends from the membrane to the lumen in the centre and is joined to adjacent ones by tight junctions

Question 12

Two compartments tight junctions divide the tubule into?

Answer 12

Basal compartment- between membrane and tight junctions and central compartment- beginning at tight junctions and including the lumen

Question 13

What does the arrangement of Sertoli cells allow (blood-testes barrier)?

Answer 13

Prevents chemical moving from blood into lumen of seminiferous tubule, ensures proper conditions for germ cell development and differentiation within the tubules, permits different stages of spermatogenesis to take place in different compartments and thus different environments

Question 14

What are undifferentiated germ cells called? When they begin to divide? They produce what types of daughter cells? Type A and Type B daughter cell do what?

Answer 14

Spermatogonia
At puberty
Type A- remain outside blood-testes barrier and produce daughter cells until death
Type B- differentiated into primary spermatocytes (in basal compartment)

Question 15

Where must primary spermatocytes pass through to to gain entry into the central compartment? What then happens? In Meiosis 2, the secondary spermatocytes differentiated into what?

Answer 15

The blood-testis barrier through tight junctions of Sertoli cells
They undergo meiosis 1–> 2 secondary spermatocytes
4 spermatids

Question 16

How do spermatids become spermatozoa? What is this also known as? What happens when sperm formation is complete?

Answer 16

They grow a tail and discard their cytoplasm to become lighter
Spermiogenesis
The cytoplasm of the Sertoli cells around the sperm retracts and the sperm are released into the lumen to be bathed in luminal fluid

Question 17

What is the tip of the nucleus covered by? Mitochondria form what section of the sperm?

Answer 17

The acrosome- a protein-filled vesicle containing enzymes to penetrate the egg
The midpiece- provide energy for movement

Question 18

GnRH secreting neuroendocrine cells of the hypothalamus fire a brief burst of action potentials how often? GnRH travels where to stimulate the release of what 2 hormones?

Answer 18

Every 90 minutes- secrete GnRH

The anterior pituitary via the hypothalamo-hypophyseal portal vessels- release LH and FSH

Question 19

In males, FSH acts on what cells to stimulate the secretion of what? LH acts on what cells to stimulate what secretion? Testosterone travels where and does what?

Answer 19

The Sertoli cells to stimulate the secretion of paracrine agents to initiate spermatogenesis
Leydig cells- stimulate testosterone secretion
Diffuses from interstitial spaces into seminiferous tubules–> Sertoli cells where it facilitates spermatogenesis

Question 20

What hormone does testosterone inhibit the secretion of? In what 2 ways does it do this?

Answer 20

LH
1) Acts on hypothalamus to decrease amplitude of GnRH burst 2) Acts on anterior pituitary to decrease LH response to GnRH

Question 21

Sertoli cells release what hormone which acts on anterior pituitary to inhibit the release of FSH? Around what month of gestation do the fetal oogonia stop dividing? During fetal life, how many oogonia turn into primary oocytes?

Answer 21

Inhibin
7th month
All oogonia differentiate into primary oocytes

Question 22

When does Meiosis I begin in females? When is meiosis then arrested at metaphase 1 until? Known as? Only what eggs will complete meiosis 1? What occurs during Meiosis 2?

Answer 22

In-utero before 12 weeks
Until puberty 
Meiotic arrest
Eggs destined for ovulation 
The secondary oocyte develops into the ovum

Question 23

When is Meiosis 2 arrested until in females? Before puberty. low level of what hormones? What happens at puberty? What is normal puberty influenced by?

Answer 23

Until fertilisation
GnRH and GHRH from hypothalamus, anterior pituitary; FSH, LH, GH and gonadal sex steroids
Increase in GnRH and GHRH, FSH, LH, GH and sex steroids
Nutrition, insulin, genetic factors and exercise

Question 24

Male changes in puberty? Female changes in puberty?

Answer 24

Testicular enlargement, pubic, axillary and facial hair growth, growth spurt, spermatogenesis begins, acne, body odour and mood changes
Breast development, pubic and axillary hair growth. growth spurt, menarche, acne, body odour and mood changes

Question 25

When is the follicular phase? Follicles begin as what? What does this consist of? What do granulosa cells secrete?

Answer 25

Day 1-13
Primordial follicles
Primary oocyte surrounded single layer of cells called granulosa cells
Oestrogen, small amounts of progesterone before ovulation, inhibin

Question 26

Primordial follicle develops into what? What happens then? What passes through these gap junctions?

Answer 26

Primary follicle
Oocyte increases in size, it becomes separated from inner granulosa cells by zona pellucida secreted by outer follicular cells, inner granulosa cells stay in contact with oocyte via cytoplasmic processes and form gap junctions
Nutrients and chemical messengers to the oocyte

Question 27

Primary follicle develops into what? What happens then? Theca and granulosa cells function together to form what?

Answer 27

Preantral follicle
Follicle grows larger through mitosis of granulosa cells, connective tissue cells around granulosa cells forms layer cells known as the ‘theca’
Oestrogen

Question 28

Preantral follicle develops into what? What happens then? Majority of follicles in ovaries are what?

Answer 28

Early antral follicle- primary oocyte reaches full size. fluid-filled space called antrum forms in midst of granulosa cells due to fluid they secrete
Still primordial, constant numbers of preantral and early antral follicles

Question 29

At start of period, how many preantral and early antral follicles–> larger antral follicles? 1 week in, only what continues to develop? Selected based on what? Non-dominant follicles undergo what process instead?

Answer 29

10-25
Dominant follicle- condition of oocyte and on oestrogen production
Atresia- form of cell death

Question 30

As the time for ovulation approaches, what happens to primary oocyte? Due to surge in what? What follicle becomes so large, it balloons out on surface of the ovary? When does ovulation occur?

Answer 30

It emerges from meiotic arrest- due to LH–> secondary oocyte
Graafian follicle
When thin walls of follicle and ovary rupture at site where they are joined due to enzymatic digestion

Question 31

What occurs during ovulation? When does this happen?

Answer 31

Secondary oocyte is carried out of the ovary and onto the ovarian surface by antral fluid= day 14

Question 32

When is the luteal phase? What happens then and what structure forms? This structure secretes what 3 hormones? It reaches maximum development within how many days? Degenerates by what process?

Answer 32

Day 14-28 
Follicle discharged antral fluid and egg, it collapses, granulosa cells enlarge greatly--> corpus luteum forms
Oestrogen, progesterone and inhibin 
10 days 
Apoptosis- this triggers menstruation

Question 33

Oestrogen produced by what? Progesterone made and released by what cells and when? Sequence of menstrual phase depends on levels of what?

Answer 33

Granulosa cells mainly during follicular phase, then by corpus luteum after ovulation
By granulosa and theca cells just before ovulation, then by corpus luteum
GnRH- change over 24 hours over menstrual cycle

Question 34

What is FSH needed for? Why does this increase as one cycle ends and next begins? It stimulates what in the first week?

Answer 34

Follicle development beyond preantral and early antral
Progesterone, oestrogen and inhibin decrease- remove -ve feedback on hypothalamus and anterior pituitary
The granulosa cells to multiply and produce oestrogen and antrum to enlarge

Question 35

What does oestrogen act as within the follicle? As the dominant follicle matures, FSH induces what to appear on the granulosa cells? Why does FSH decrease more than LH?

Answer 35

A paracrine/ autocrine agent- stimulates proliferation of granulosa cells- further increases oestrogen production
LH receptors
Granulosa cells secrete inhibin which inhibits mainly FSH secretion

Question 36

When is the ‘LH surge’? Followed by what? LH acts on theca cells in the first week to do what? Where do these androgens then diffuse into and do?

Answer 36

Around 18 hours before ovulation
Rapid decrease and then a further slow decline during the luteal phase
To proliferate and to make androgens- granulosa cells and converted to oestrogen by aromatase

Question 37

When does oestrogen levels increase rapidly? Decreases before what has peaked? Followed by what? Ends with what?

Answer 37

Low and stable in 1st week–> increases rapidly during second week and dominant ovarian follicle grows and secretes more oestrogen
Before LH peak–> a second increase due to secretion by corpus luteum
Rapid decrease during last days of cycle

Question 38

When are very small amounts of progesterone released by the ovaries? Why large increase? When does inhibin increase?

Answer 38

During the follicular phase until just before ovulation
Due to corpus luteum- the rapid decrease during last days of cycle
During late follicular phase–> high during luteal phase and decreases until corpus luteum degenerates

Question 39

Large oestrogen amounts during luteal phase act on anterior pituitary to do what? Leads to what? Why does LH surge start to decline?

Answer 39

Increase sensitivity of LH-releasing cells to GnRH (from hypothalamus)= +ve feedback mechanism
LH surge and ovulation–> act upon granulosa cells induce ovulation
Due to small increase in progesterone from corpus luteum inducing -ve feedback on anterior pituitary and hypothalamus

Question 40

Corpus luteum degrades within how many weeks if no pregnancy? Day 1 of period known as what? Epithelia lining uterus known as what degenerates?

Answer 40

2 weeks
The Menstrual phase- lasts 3-5 days
The endometrium–> menstrual flow

Question 41

From 5 of menstrual cycle, known as what? What happens then?

Answer 41

The proliferative phase- around 10 days
Flow ceases, endometrium begins to thicken due to oestrogen–> growth of endometrium and myometrium (underlying smooth muscle), also synthesis of receptors for progesterone in endometrial cells

Question 42

After the proliferative phase, what phase occurs? What happens then? What acts upon the oestrogen-primed endometrium to turn it into an actively secreting tissue?

Answer 42

The secretory phase- between ovulation and onset of next menstruation
Endometrium starts to secrete glycogen in glandular epithelium, then glycoproteins and mucopolysaccharides
Progesterone- makes endometrium a hospitable environment for implantation and nourishment of embryo

Question 43

How does progesterone influence the myometrium?

Answer 43

Progesterone inhibits myometrial contractions- opposing stimulatory actions of oestrogen and prostaglandins (ensures fertilised egg can safely implant into uterus)

Question 44

How does oestrogen affect the cervical mucus? most pronounced when? Progesterone influences cervical mucus how?

Answer 44

Makes it abundant, clear and watery
During ovulation to allow sperm to move easily on way to uterus and fallopian tubes
Thick and sticky- after ovulation (plug prevents bacteria from entering uterus via vagina)