1.1 Development of the reproductive system

Question 1

How do new individuals arise?

Answer 1

from fusion of 2 haploid gametes

Question 2

what does fusion of 2 haploid gametes form?

Answer 2

diploid conceptus (embryo)

Question 3

where do gametes (sex cells: sperm / ova) originate from?

Answer 3

diploid germ cells (diploid sex cells)

undergo meiosis –> haploid gametes

Question 4

what are diploid germ cells?

Answer 4

embryonic cells that have the potential to develop into spermatozoa / ovum (gametes)

Question 5

what are gametes?

Answer 5

spermatozoa or ovum
(sex cells - haploid)
from diploid germ cells

Question 6

where do diploid germ cells separate from?

Answer 6

separated from somatic cells early in embryonic life

Question 7

what is the male and female gamete?

Answer 7

female gamete = ovum

male gamete = sperm

Question 8

what is the male gametes production rate? why?

Answer 8

7000 sperm / second

have to exploit (make use of) the intermittent female activity

Question 9

what is the production of female gametes like?

Answer 9

limited by the number that can be supported by gestation

about 400 in total fertile lifespan (40 years), 12-14 per year (between conception to birth)

Question 10

where are gametes produced?

Answer 10

in the gonads

Question 11

what are the male and female gonads?

Answer 11

males = testis
female = ovary

Question 12

aside from gonads, what is the remainder of the reproductive system divided into?

Answer 12

internal and external genitalia

Question 13

what are the female internal genitalia?

Answer 13

Ovaries
Duct system:
vagina
cervix
uterus
fallopian tube

Question 14

what are the female external genitalia?

Answer 14

vestibule
labia minora & majora
clitoris
perineum

Question 15

what are the male internal genitalia?

Answer 15

testis
Duct system: epididymus, vas deferens, (urethra)
seminal vesicles
prostate
bulbo-urethral gland

Question 16

what are the male external genitalia?

Answer 16

penis

scrotum

Question 17

when do secondary (sexual) characteristics arise?

Answer 17

at puberty when gametes begin to be produced

Question 18

what does secondary characteristics aid?

Answer 18

facilitate sexual interaction

Question 19

what are the secondary characteristics in females?

Answer 19

decrease in body size (relative to male)
subcutaneous fat distribution
hair & skin changes
breast development
smell & touch become more acute
CNS effects

Question 20

what are the secondary characteristics in male?

Answer 20

increase in body size (relative to female)
change in body composition
hair & skin changes
pain experienced more acutely
CNS effects

Question 21

what are the secondary characteristic changes coordinated by?

Answer 21

hormones e.g. those by pituitary gland (FSH & LH) or from gonads (testosterone, oestrogen & progesterone)

Question 22

what do the hormones in repro coordinate?

Answer 22

production of gametes
mechanisms of gestation
parturition (birth)

Question 23

where are the repro hormones produced from?

Answer 23

hypothalamus
anterior & posterior pituitary gland
gonads
placenta

Question 24

what are the hormones produced in the hypothalamus?

Answer 24

peptides releasing factors:
GnRH (gonadotrophin releasing hormone)
FSH (follicle stimulating hormone)
LH (leutinising hormone)

Question 25

which hormone is produced in the posterior pituitary gland?

Answer 25

oxytocin | hypothalamus neural control

Question 26

what are the hormones produced in the anterior pituitary gland?

Answer 26

gonadotrophins: FSH (follicle stimulating) LH (leutinising)

Question 27

which hormones are produced by the gonads? (ovaries & testis)

Answer 27

gonadal steroids: male = testosterone females = oestrogens (oestradiol, oestrone, oestriol) & progesterone inhibin

Question 28

what are the hormones produced by the placenta?

Answer 28

human chorionic gonadotrophin (hCG) human placental lactogen (hPL) Oestrogen (oestradiol, oestrone, oestriol) Progesterone

Question 29

when do germ cells arise?

Answer 29

3 weeks after conception

Question 30

what is the genetic sex of an individual determined by?

Answer 30

the chromosome (XX or XY) of the germ cells which arise 3 weeks post conception

Question 31

what is the developed gonad made up of?

Answer 31

somatic cells from original primordium (early structure) and germ cells

Question 32

what does primordial gonad consist of?

Answer 32

cortex and a medulla

Question 33

what can the primordial gonad form?

Answer 33

ovary or testis - depending on genetic sex

Question 34

how do male germ cells develop from the primordial gonad?

Answer 34

colonise in the medullary region, cortex region will atrophy M = Medullary, Male thick tunica albuginea (enclose gonads tightly)

Question 35

what do the germ cells within males allow for?

Answer 35

rapid growth of the definitive sex cords

Question 36

where does structural development occur?

Answer 36

in utero

Question 37

when does functional development and maturation occur?

Answer 37

continues after birth

Question 38

what is the indifferent stage of development of reproductive tracts?

Answer 38

gonad and duct systems

Question 39

what is the developmental 'cross-roads' stage of reproductive tracts regulated by?

Answer 39

genetic sex: XX or XY

Question 40

what is the urogenital ridge?

Answer 40

region of intermediate mesoderm giving rise to both embryonic kidney and gonad

Question 41

what is indifferent gonad derived from?

Answer 41

intermediate mesoderm + primordial germ cells (extragonadal)

Question 42

Where do primordial germ cells arise from? where do they migrate to? what do they form?

Answer 42

arise in yolk sac, migrate into retroperitoneum, along dorsal mesentery into UG ridge forming primordial gonads, mesonephric origin

Question 43

what determines the genetic male?

Answer 43

male gamete (sperm) carrying Y chromosome primordial germ cells carry Y chromosome (meiosis to form haploid gamete) so XY male conceptus (embryo)

Question 44

what physical characteristics (organs) determine male?

Answer 44

``` gonad (testis) internal genitalia (duct system) external genitalia ```

Question 45

what drives the development of MALE?

Answer 45

expression of SRY genes

Question 46

what determines genetic female?

Answer 46

male gamete carrying X chromosome (XX female conceptus) | primordial germ cells do NOT carry Y chromosome

Question 47

what leads to development of female?

Answer 47

absence of Y chromosome

Question 48

what is the female gonad?

Answer 48

ovary

Question 49

how do female germ cells develop from the primordial gonads?

Answer 49

colonise the cortex of primordial gonad (containing primordial of follicles) medullary cords regress no tunica albuginea

Question 50

what is the (indifferent stage) duct systems that develop? where do they end?

Answer 50

mesonephric (embryonic kidney ducts) and paramesonephric ducts developes in both male & female embryos both end in cloaca

Question 51

what is the mesonephric system?

Answer 51

mesonephric tubules which perform primitive renal function (filter blood - nephrons)

Question 52

what makes up the embryonic kidneys?

Answer 52

mesonephric tubules + mesonephric duct

Question 53

what is mesonephric duct also know as? what is it's direction of travel? what does it make contact with?

Answer 53

Wolffian duct runs caudally make contact with cloaca