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repro Flashcards

1
Q

what is the barr body?

A

in the XX genotype, only one chromosome active. Other chromosome forms a Barr body/sex chromatin nuclear mass. Can identify gender from skin cells. XY does not show this.

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2
Q

Where and when do male and female gonads develop from?

A

urogenital ridge
undifferentiated in week
testes develop in week 7
ovaries develop in week 11

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3
Q

why do only the tips of chromosomes undergo recombination in a male XY?

A

to avoid transfer of SRY gene from Y chromosome to X chromosome

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4
Q

describe the primitive reproductive tract

A

Wolffian and Mullerian tubes

common external opening

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5
Q

describe SRY gene influence

A

SRY gene produces SRY protein.
SRY stimulates primordial gonads to form testes
next the sertolli cells secrete Mullerian inhibiting substance MIS. causing duct to regress.

Leydig cells secrete testosterone which stimulates wolffian duct to form the epididymis, vas deferens, seminal vesicles and ejaculatory duct.

Testosterone also stimulates secretion of dihydrotestosterone. This causes development of the penis, scrotum and prostate.

testis descend into the scrotum, this is stimulated by testosterone

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6
Q

describe the testes

A

seminiferous tubules produce sperm
tubules converge to form the rete testis
leave testes via efferent ductules to the epididymis
leads on to the vas deferens

lumen filled with nutrient rich fluid secreted by Sertolli
surrounded by sertolli cell ring
basement membrane
leydig cells outside

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7
Q

describe the blood testis barrier

A

ring of sertolli cells with tight junctions

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8
Q

how long does spermatogenesis take

A

64 days

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9
Q

describe spermatogenesis

A

occurs at puberty
FSH and LH facilitate

spermatogonium located in the basal compartment (between basal membrane and tight junctions).
FSH on sertolli cells causes release of paracrine agents that lead to proliferation and differentiation of spermatogonium.

mitosis resulting in primary spermatocytes
not all spermatogonium are converted to primary spermatocytes but are reformed to stem cell spermatagonium. those that remain outside blood testis barrier are Type A. Type B cells go on to form primary spermatocytes.

primary spermatocytes undergo meiosis to form secondary spermatocytes as they emerge into the central compartment, passing through sertolli tight junctions

secondary spermatocytes undergo meiosis 2 to form four spermatids. Throughout this, movement from basement membrane through tight junctions, closer to lumen.

undergo spermatiogenesis where they form characteristic sperm cell structure. During this phase they embed themselves into the sertoli cell plasma membrane. once complete the sertolli cytoplasms retracts and spermatozoa cells released into the seminifeorus tubule.

  1. Golgi phase - formation of vesicles containing glycoproteins
  2. CAP phase vesicle forms the acrosome
  3. Acrosome phase where spermatazoon embeds itself in the sertoli layer and flagellum and midpiece develop.
  4. MATURATION embed in sertoli cell layer, with flagellum extending into seminiferous canal lumen. excess cytoplasm is pinched off. spermatazoon formed and released into seminiferous canal.
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10
Q

what are the roles of sertolli cells

A

secrete MIS in the embryological phase

secrete nourishing fluid into seminiferous tubule lumen. contains Androgen binding protein. binds to testosterone, keeps concentration of testosterone high.

respond to FSH and testosterone to release paracrine agents, these stimulate differentiation of spermatogonium.

form sertolli cell barrier

secrete inhibin to inhibit FSH

phagocytose defective sperm

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11
Q

what do the leydig cells do

A

secrete testosterone

also stimulates secretion of dihydrotestosterone in embyo

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12
Q

describe oogenesis

A

oogonia (primitive germ cells) divide by mitosis, finish at month 7.

7 million primary oocyte produced. these differentiate to form primary oocytes.

begins meiosis 1 arrested at metaphase 1.

at birth only 1 million primary oocyte

continues at puberty just before ovulation.
secondary oocyte formed and primary polar body, released by follicle at ovulation.

undergoes meiosis 2 but arrested in metaphase 2. Continues only if fertilised.

one cell receives most of the cytoplasm. net result is one ovum, whilst in spermatogenesis it is 4.

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13
Q

describe the HPG axis

A

hypothalamic pituitary gonadal axis

hypothalamus secretes GnRH

stimulates anterior pituitary to secrete FSH and LH

LH causes the THECA cells to convert cholesterol –> androstenedione.

Androstenedione diffuses into granulosa cells. FSH stimulates conversion of Androstenedione into oestrogen.

Oestrogen stimulates building of uterus wall. Between days 12-14 it stimulates FSH and LH. causes ovulation

Other times of the cycle in inhibits.

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14
Q

what are germ cells

A

cells that develop into ova and sperm
originate from the yolk sac of the hund guy
specialised cells

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15
Q

name the penile compartments

A

corpus cavernosum x 2

corpus spongiusum which transmits the urethra

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16
Q

how is the scrotum kept at 2* cooler temperature?

A

pampiform plexus

heat exchange mechanism in the blood vessels and air circulation

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17
Q

what is the epithelium of the rete testis?

A

simple cuboidal

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18
Q

what is the epithelium of the efferent ductules?

A

pseudostratified columnar

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19
Q

what is the epididymis lined by?

A

pseudostratified columnar with stereocilia

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20
Q

what is the epithelium of the vas deferens

A

pseudostratified columnar

21
Q

out of the 2-5 ml fluid expelled during orgasm, how much is seminal, prostatic and sperm?

A

60% seminal
30% prostatic
10% sperm and trace of bubourethral

22
Q

what do prostate and seminal vesicle secretions contain?

A

buffer to protect sperm against vaginal acidic secretion

chemicals to increase sperm motility, fructose for energy

prostaglandins to stimulate female peristaltic action

23
Q

describe the pathway of sperm

A 
seminiferous tubule
rete testis
efferent tubules
epididymis
vas deferens
seminal gland 
ejaculatory duct 
prostate 
bulbourethral gland
urether 
penile urethra
24
Q

what are the 2 divisions of the seminiferous tubule

A

basal compartment - from basement membrane and the tight junctions

central compartment, from tight junctions and including the lumen

25
Q

how frequently is gonadotropin releasing hormone released from the hypothalamus in males?

A

every 90 minutes

26
Q

how does GnRH trigger FSH and LH release?

A

hypothalami hypophyseal portal system

27
Q

describe the hypothalamic pituitary gonadal axis in males

A

GnRH released every 90 minutes
release of FSH and LH from the anterior pituitary

FSH acts on sertolli cells to stimulate secretion of paracrine agents required to initiate spermatogenesis.

FSH also stimulates sertolli cells to release protein hormone INHIBIN which acts on the anterior pituitary to inhibit release of FSH.

LH acts on leydig cells to stimulate testosterone secretion.

testosterone acts locally by diffusing from interstitial space into the seminiferous tubule.

testosterone enters the sertoli cells where it helps to facilitate spermatogenesis

testosterone also inhibits LH secretion. 1) it acts on the hypothalamus to decrease the amplitude in GnRH burst. 2) acts directly on the anterior pituitary to decrease LH response to GnRH

28
Q

describe the myometrium

A

smooth muscle bundles which orientate in various directions

29
Q

what is the epithelium of the ovary?

A

simple cuboidal epithelium

30
Q

what epithelium lines the fimbriae?

A

ciliated epithelium

31
Q

what is the epithelium of the uterus

A

simple columnar ciliated epithelium

32
Q

what is the epithelium of the cervix?

A

simple columnar epithelium

33
Q

what is the epithelium of the vagina?

A

moist stratified squamous

keratinised towards the vulva end

34
Q

state the differences between spermatogenesis and oogenesis

A
  1. oogensis not a continous process but disjointed
  2. in spermatogenesis both maturations occur in the testic wherease in females one occurs in ovary and one in fallopian tube after fertilisation
  3. 1 oocyte forms 1 ovum. 1 spermatocyte forms 4 spermatozoa
35
Q

what are the changes which happen during puberty

A

before puberty
hypothalamic secretion of GnRH and GHRH is low
low levels of anterior pituitary FSH LH and GH release
low level gonadal sex steroids

at puberty
GnRH and GHRH increase
increase in FSH LH GH and sex steroids.

36
Q

describe the physical features that change during male puberty

A 
starts at 9-14
testicular enlargement
pubic axillary and facial hair growth 
growth spurt 
spermatogenesis begins
acne, body odour and mood change
37
Q

describe the physical changes at female puberty

A 
starts at 8-14
breast development
pubic and axillary hair growth 
growth spurt
menarche 2.5 years after puberty begin 
acne, body odour, mood change
38
Q

describe the follicular phase of the menstrual cycle

A

Follicular phase

• Menstrual phase

  • Oestrogen and progesterone are low because previous corpus luteum regressing.
  • Secretion of FSH and LH released from inhibition.
  • Around 10-15 of the preantral and early antral follicles are stimulated to mature into larger antral follicles.

• Proliferative phase

  • A dominant follicle is selected.
  • LH causes theca cells to produce androstenedione. Enzyme desmolase
  • FSH enables granulosa cells to produce oestrogen from aldostenedione. Enzyme aromatase.
  • FSH also induces formation of LH receptors on granulosa cells.
  • Plasma oestrogen increases due to dominant follicle secretion
  • Oestrogens stimulates endometrium to proliferate.
  • FSH decrease (and LH to a lesser extent) due to oestrogen and inhibin (affects mainly FSH) negative feedback.
  • Therefore atresia of the non dominant follicles occur.
  • LH surge is initiated by increasing plasma oestrogen during the late follicular phase. Oestrogen acts to increase LH releasing cells to GnrRH on the anterior pituitary.
  • High plasma LH acts on granulosa cells to stimulate ovulation
  • Oocyte is induced to complete meiosis 1 and undergo cytoplasmic maturation.
  • Follicle is stimulated to secrete digestive enzymes and prostaglandin
  • Ovulation mediated via digestive enzymes and prostaglandin
39
Q

describe the luteal phase of the menstrual cycle

A

day 14- 28-

Corpus luteum forms and under the influence of low but adequate LH levels, secretes oestrogen and progesterone and inhibin.

  • Progesterone inhibits LH causing it to decrease after peak. It does this by inducing negative feedback on both the hypothalamus and anterior pituitary
  • Progesterone and oestrogen stimulate edometrium to form the secretory endometrium. This starts to secrete glycogen, glycoproteins and mucopolysaccarides.
  • Secretion of FSH and LH is inhibited, so no new follicles develop.
  • Corpus luteum degenerates if no implantation occurs
  • Plasma oestrogen and progesterone decreases
  • Endometrium begins to slough at day 28 and a new cycle can begin
40
Q

where is the oestrogen secreted?

A

by the granulosa cell during the follicular phase

after ovulation by the corpus luteum.

41
Q

where is the progesterone secreted?

A

just before ovulation, by theca and granulosa cells produce small amounts.

after ovulation, corpus luteum is the major producer.

42
Q

How is the GnRH input different in males and females?

A

in males release every 90 minutes

in females, levels change over course of menstrual period.

43
Q

what enzyme is used by theca cells to synthesise androstenedione

A

desmolase

44
Q

what enzyme is used by granulosa cells to synthesis oestrogen

A

aromatase

45
Q

what occurs during menstrual phase

A 
day 1-5
progesterone withdrawal
stromal haemorrhafe
granulocytes in stroma
stromal and glandular gramentation
46
Q

what are the 2 divisions of the follicular phase

A

menstrual 1-5

proliferative 5-14

47
Q

what happens during the proliferative phase

A

menstrual flow ceases
endometrium and myometrium thickens due to oestrogen

oestrogen induces synthesis of progesterone receptors in endometrial cells.

48
Q

what are the segments of the luteal phase

A

secretory phase 14-28

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