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MEDSCI 142 > Reproductive Lab > Flashcards

Reproductive Lab Flashcards

1
Q

spermatogenesis

A
  • spermatogonial stem cells (2n = 46) → mitosis
  • some spermatogonia remain near basement membrane and remain undifferentiated
  • some spermatogonia lose contact with basement membrane → squeeze through tight junctions of blood-testis barrier → undergo developmental changes → differentiate into primary spermatocytes
  • primary spermatocytes (2n = 46) replicate its DNA → meiosis I → secondary spermatocytes
  • secondary spermatocytes (n = 23, each chromosome has two chromatids) → meiosis II → spermatids
  • spermatids (n = 23, each chromosome has one chromatid)
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2
Q

unique process of spermatogenesis

A
  • as spermatogenic cells proliferate, they fail to complete complete cytoplasmic separation (i.e. cytokinesis)
  • remain in contact via cytoplasmic bridges
  • likely accounts for synchronised production of sperm in any given area of seminiferous tubule
  • provides survival value as half of sperm has X chromosome and other half has Y chromosome, larger X chromosome may carry genes needed for spermatogenesis that are lacking on the smaller Y chromosome
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3
Q

spermiogenesis

A
  • development of spherical spermatids → elongated, slender sperm
  • acrosome forms above the nucleus
  • flagellum develops
  • mitochondria multiply
  • sustentacular cells (i.e. sertoli) dispose of excess cytoplasm
  • finally sperm are released from the connections to sustentacular cells (i.e. spermiation)
  • sperm enter lumen of seminiferous tubule
  • fluid secreted by sustentacular cells push sperm towards the ducts of the testes
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4
Q

oogenesis

A
  • begins before female is born
  • primordial germ cells migrate from yolk sac → ovaries
  • germ cells differentiate → oogonia
  • oogonia (stem cells, 2n = 46) → mitosis → millions of germ cells
  • most of these germ cells degenerate (i.e. atresia)
  • germ cells → primary oocytes
  • primary oocytes are surrounded by single layer of follicular cells (i.e. primordial follicle)
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5
Q

ovarian cortex

A
  • surrounds primordial follicles
  • consists of collagen fibres and stromal cells (fibroblast-like)
  • at birth → 200,000~2,000,000 primary oocytes in each ovary
  • at puberty → 40,000 primary oocytes in each ovary
  • ~400 mature and ovulate during a woman’s reproductive lifetime
  • remainder undergo atresia
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6
Q

follicular development

A
  • each month after puberty, gonadotropins (i.e. FSH/LH) secreted by anterior pituitary stimulate development of primordial follicles
  • primordial follicles -> primary follicles -> secondary follicles -> mature/Graafian follicles
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7
Q

primary follicles

A
  • primary oocyte surrounded by several layers of granulosa cells
  • outermost granulosa rests on basement membrane
  • as it grows, forms a clear glycoprotein layer (i.e. zona pellucida) between primary oocyte and granulosa cells
  • stromal cells surrounding basement membrane form layer (i.e. theca folliculi)
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8
Q

secondary follicles

A
  • theca differentiated into two layers
  • theca interna → highly vascular internal layer, has cuboidal secretory cells that secrete oestrogens
  • theca externa → outer layer of stromal cells and collagen fibres
  • granulosa cells secrete follicular fluid, build up in cavity (i.e. antrum) in centre of follicle
  • innermost layer of granulosa cells become firmly attached to zona pellucida (i.e. corona radiata)
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9
Q

mature/graafian follicles

A
  • diploid primary oocyte (2n = 46) → meiosis I → two unequal haploid cells (n = 23, two chromatids in a chromosome)
  • smaller cell (i.e. first polar body) is a packet of discarded nuclear material
  • larger cell (i.e. secondary oocyte) recieves most of cytoplasm
  • meiosis II begins
  • rupture of mature follicle releases secondary oocyte (i.e. ovulation)
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10
Q

ovulation

A
  • secondary oocyte, first polar body, and corona radiata released into pelvic cavity
  • normally are swept into uterine tube
  • if fertilisation does not occur → cells degenerate
  • if sperm is present → meiosis II continues
  • first polar body → splits into two polar bodies → degenerates
  • secondary oocyte (n = 23, two chromatids in a chromosome) → two unequal haploid cells (n = 23, one chromatid in a chromosome)
  • smaller cell → second polar body → degenerates
  • larger cell → ovum
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11
Q

difference in gamete production between sexes

A
  • male → one primary spermatocyte produces four gametes (i.e. sperm)
  • female → one primary oocyte produces a single gamete (i.e. ovum)
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12
Q

oestrogen

A
  • promote development and maintenance of female reproductive structures, secondary sex characteristics
  • increase protein anabolism (i.e. building strong bones)
  • lower blood cholesterol level
  • moderate levels in the blood inhibit GnRH and LH/FSH
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13
Q

progesterone

A
  • secreted mainly by corpus luteum
  • cooperates with oestrogens to prepare and maintain endometrium and mammary glands for pregnancy
  • high levels in the blood inhibit GnRH and LH
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14
Q

relaxin

A
  • produced by corpus luteum
  • relaxes uterus by inhibiting contractions of myometrium (implantation occurs more readily in relaxed state)
  • placenta produces more relaxin in pregnancy → helps to dilate the uterine cervix
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15
Q

inhibin

A
  • secreted by granulosa cells of growing follicle and by corpus luteum after ovulation
  • inhibits secretion of FSH and LH (to a lesser extent)
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16
Q

phases of female reproductive cycle

A
  • menstrual cycle -> first 5 days
  • preovulatory phase -> days 6-13
  • ovulation -> day 14
  • postovulatory phase -> days 15-28
17
Q

events in uterus during menstrual phase

A
  • declining levels of progesterone and oestrogens → stimulate release of prostaglandins → cause uterine spiral arterioles to constrict
  • cells of stratum functionalis become oxygen deprived, die, and sloughs off
  • only stratum basalis remains
18
Q

events in ovaries during menstrual phase

A
  • FSH initiates development of primordial follicles → primary follicles → secondary follicles
  • may take several months to occur
  • therefore follicle that develops at beginning of menstrual cycle may not ovulate until several menstrual cycles later
19
Q

events in ovaries during preovulatory phase

A
  • secondary follicles begin to secrete oestrogens and inhibin
  • a single secondary follicle in one ovary has outgrown all of the others (i.e. dominant follicle)
  • oestrogen and inhibin secreted by dominant follicle → decreases secretion of FSH → causes less dominant follicles to stop growing, undergo atresia
  • dominant follicle → develops into mature follicle → increases its production of oestrogens
20
Q

events in uterus during preovulatory phase

A
  • oestrogens released by follicles in the blood → stimulate repair of endometrium
  • cells of stratum basalis → mitosis → produce new stratum functionalis
  • endometrial glands develop, arterioles coil and penetrate stratum functionalis
  • thickness of endometrium doubles
21
Q

events during ovulation

A
  • high levels of oestrogens during last part of preovulatory phase → positive feedback on LH and GnRH → LH surge causes rupture of mature follicle
  • mature follicle ruptures → secondary oocyte (surrounded by corona radiata and zona pellucida) is released into pelvic cavity → swept in to uterine tube
22
Q

events in ovary during postovulatory phase

A
  • mature follicle collapses → basement membrane between granulosa cells and theca interna breaks down → blood clot forms → corpus hameorrhagicum
  • theca interna cells mix with granulosa cells under influence of LH → corpus luteum
  • corpus luteum is stimulated by LH → secretes progesterone, oestrogens, relaxin, and inhibin, and absorb the blood clot
  • if oocyte is not fertilised → corpus luteum has a life span of 2 weeks → secretory activity declines → degenerates into corpus albicans → decreased progesterone, oestrogen, inhibin → release of GnRH, FSH, LH rises → follicular growth resumes → new ovarian cycle begins
  • if oocyte is fertilised → hCG released by chorion of embryo → stimulates secretory activity of corpus luteum → persists past its lifespan of 2 weeks
23
Q

events in uterus during postovulatory phase

A
  • corpus luteum secretes progesterone and oestrogen → promotes growth and coiling of endometrial glands, vascularisation of stratum functionalis
  • prepatory activity peaks ~1 week after ovulation, around the time that a fertilised ovum might arrive in the uterus
  • if fertilisation does not occur → levels of progesterone and estrogens decline due to degeneration of corpus luteum
24
Q

ovarian cycle

A
  • follicular phase -> - menstrual phase + preovulatory phase, ovarian follicles are growing and developing
  • luteal phase -> postovulatory phase, corpus luteum is formed
25
Q

uterine cycle

A
  • proliferative phase -> preovulatory phase, endometrium is proliferating
  • secretory phase -> postovulatory phase, secretory activity of endometrial glands
26
Q

female athlete triad

A
  • disordered eating, amenorrhea, premature osteoporosis
  • athletes experience pressure to lose weight → develop disordered eating behaviours
  • low levels of leptin produced by adipose cells → reduced secretion of GnRH → decreased release of LH/FSH → ovarian follicles fail to develop, ovulation does not occur, synthesis of oestrogen/progesterone wanes → absence of menstruation (i.e. amenorrhea)
  • low levels of oestrogens → loss of bone mineral density → osteoporosis
27
Q

what could be the cause of decreased concentrations of FSH, LH, oestrogen and progesterone?

A
  • delayed puberty
  • lower body fat due to female athlete triad
28
Q

area of relevance and mechanism of action of male condom

A
  • area of relevance -> penis/penile urethra
  • mechanism of action -> barrier
29
Q

area of relevance and mechanism of action of vasectomy/tubal ligation

A
  • area of relevance -> ductus deferens/uterine tubes
  • mechanism of action -> surgical
30
Q

area of relevance and mechanism of action of diaphragm

A
  • area of relevance -> cervix
  • mechanism of action -> barrier
  • more effective when used with spermicide
31
Q

mechanism of action of oral contraception

A
  • hormonal
  • combined oral contraceptives → contain progestin and oestrogens → suppress FSH/LH → prevents development of dominant follicle
  • progestin only pills → thicken cervical mucous → make it more difficult for sperm to enter uterus, does not consistently inhibit ovulation
32
Q

area of relevance and mechanism of action of IUD

A
  • area of relevance -> uterine tubes
  • mechanism of action -> chemical (i.e. basic/copper material messes up sperm motility)
33
Q

label diagram of male reproductive system

A
34
Q

label diagram of female reproductive system

A
35
Q

label image of rat testis

A
36
Q

label diagram of female reproductive cycle

A
37
Q

label diagrams of ovary histology

A

MEDSCI 142 (6 decks)

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