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Embryology > Embryology Week 1 > Flashcards

Embryology Week 1 Flashcards

1
Q

Which glands controls sexual cycles in females and how

A
  • hypothalamus release gonadotropin releasing hormone ( GnRH )
  • acts on cells of anterior lobe of pituitary gland ( adenohypophysis ) releases gonadotropins follicule stimulating hormone and lutenizing hormone
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2
Q

Function of FSH

A
  • does not develop primordial to 1• but without it oocytes become atretic and die
  • stimulate growth of granulosa around oocyte
  • stimulate development of growing oocyte into vesicular
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3
Q

How many ooctyes reach maturity , how many discharged and what happens to the rest

A
  • 15-20
  • 1
  • degenerate and replaced by CT forming corpus atreticum
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4
Q

Function of growth differentiation factor 9

A

-proliferation of granulosa

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5
Q

How is estrogen formed and other product formed

A

-theca produces testosterone and granulosa converts it to estrogen and 17 Beta estradiol

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6
Q

Effect of estrogen

A

1 uterine endometrium enters follicular phase
2 stimulate adenohypophysis LH production
3 thins cervical mucus to allow sperm to pass through

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7
Q

Function of LH

A
  • develops Vesicular into graafian stage
  • elevates maturation promoting factors causing ooctyes to complete meiosis 1 and initiate 2
  • causes follicular rupture and ovulation
  • stimulates production of progesterone by follicular stromal cells ( lutenization )
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8
Q

State of meiosis and ovary before ovulation

A
  • meiosis 1 complete and 2 arrested at metaphase 3 hours before ovulation
  • ovary bulges at apex spot , stigma appears
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9
Q

Effects of high LH

A
  • high LH levels increase collagenase activity to digest CT around follicule
  • prostaglandin increases and causes local muscle contractions in the ovarian wall to extrude oocyte and cumulus oophorus ( ovulation )
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10
Q

What is corpus Luteum and corona radiata

A
  • follicule without cumulus oophorus and oocyte

- cumulus oophorus cells rearranged around zona pellucida

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11
Q

How is corpus luteum formed and function

A
  • granulosa and theca are vascularized under LH influence
  • develop yellowing pigment and differentiate into lutein cells to form

-secrete estrogen and progesterone to develop uterine mucosal to enter secretary stage to prepare for implantation

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12
Q

How is ovary swept into fallopian / uterine tubes

A
  • fimbrilae sweep over surface of tube and begin to contact rhythmically
  • oocyte and radiata carried into tube by rhythmic pattern
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13
Q

What happens to oocyte and oophorus once in tube

How is oocyte moved though uterine tube and what controls the rate

How many days for fertilized oocyte to reach uterine lumen

A

-cumulus withdraws cyto processes , lose contact with oocyte and rearranges into radiata

/peristaltic muscles contractions of tube and ciliary epi

  • endocrine status during and after ovulation
  • 3 to 4 days
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14
Q

How is corpus alibican formed

A

-if fertilization does not occur luteum reaches max development after 9 days.
-luteum shrinks due to luteolysis ( degeneration of lutein cells )
And forms mass of fibrocytotic scar tissue called corpus alibicans

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15
Q

What happens to luteum if oocyte fertilized

A
  • degeneration of corpus luteum prevented by human chorionic gonadotropin secreted by synctiotrophoblast of embryo
  • luteum grows and forms corpus luteum graviditatis ( of pregnancy )
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16
Q

What happens to graviditatis at end of 1st trimester and end of 4th month

What happens if graviditatis is removed 4 months before

How does luteum grow

A
  • 1/3 to half of ovary
  • regresses slowly as placenta secretion of progesterone is sufficient
  • abortion
  • hypertrophy and accumulation of lipid
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17
Q

Function of progesterone and where secreted

A
  • secreted by corpus luteum

- prepares uterus for pregnancy

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18
Q

Ampullae location and function

A
  • immediately after fimbrilallae

- site of fertilization

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19
Q

List phases of fertilization

A

1 penetrating radiata

2 penetrate zona pellucida

3 fusion of oocyte and spermatozoon membrane

20
Q

What is fertilization

How do spermatozoa move from cervix to ampulla

A
  • fusion of male and female gametes to form a zygote

- muscular contractions of uterus and uterine tube and little own propulsion

21
Q

What happens to spermatozoa at isthmus and at ovulation

A
  • less motile and cease migration

- chemoattractants from cumulus of oocyte make sperm motile again and move towards ampulla

22
Q

What is needed for a spermatozoa to fertilize an egg

A

1 capacitation

2 acrosome reaction

23
Q

What is capacitation , where does it occurs and how does it come about

What happens to the spermatozoa

Function of capacitation

A

Period of conditioning in female reproductive tract of spermatozoa

  • in uterine tube
  • epithelium interactions between spermatozoa and mucosal surface of tube
  • glycoprotein coat and seminal plasma protein removed form plasm overlying acrosomal region
  • to pass corona radiata
24
Q

What is acrosomal reaction , where occurs and what happens to sperm and what induces it

A

/Occurs after spermatozoa binds to zona.

  • is induced by zona proteins
  • release of enzymes to penetrate zona ( acrosin and typsin type substances )
  • acrosome dissolved
25
Q

Which spermatozoa can pass through radiata and purpose of spermatozoa which don’t fertilize egg

A
  • only capacitated ones

- aid in penetration of barrier

26
Q

What is zona made of and functions

What mediates zona function and what does it do

A
  • glycoprotein shell
  • facilitates spermatozoa binding and acrosome reaction
  • ligand ZP3 zona protein
  • induce release of acrosin and trypsin which dissolve zona
27
Q

What happens to oocyte membrane after coming in contact with spermatozoa

A

-permeability increases , release of lysosomal enzymes from cortical granules in plasma wc alters zona to prevent other spermatozoa penetration

28
Q

How do oocyte and spermatozoa membrane initially fuse

What happens to sperm after fusion

A
  • integrins ( oocyte ) and disintergrins ( spermatozoa ) mediate initial adhesion
  • head and tail enters but plasma stays behind
29
Q

Oocyte response to fusion And

A

1 cortical and zona reactions-to also prevent polyspermy

2 resumption of meiosis by 2• oocyte-one daughter is 2nd polar body and other definitive oocyte

3 metabolic activation of egg -factors carried by spermatozoa. Activation is initial cellular and molecular events of early stages embryogenesis

30
Q

What happens to spermatozoa after fusion

What happens to nuclei after fusion

A
  • spermatozoa moves towards female pro nucleus
  • nucleus swollen and becomes male pronucleus

-pronuclei move close lose membranes and fuse

31
Q

Why should pronuclei replicate during they growth

A
  • to prevent each cell from acquiring haploid number of cells
  • chromosomes attach at spindle for mitosis and are slit towards opposite poles and the centromeres
32
Q

Main results of fertilization

A

1 restoration of diploid number of chromosomes

2 determination of sex

3 initiation of cleavage

33
Q

When does cleavage occur , what is it

A
  • when zygote has reached 2 cell stage

- rapid mitotic division of cells becoming smaller and smaller to form blastomeres

34
Q

How is zygote like before and after 3rd mitotic division

A
  • loose clump of cells

- cells maximize contact forming compact ball of cells held together by tight junctions ( segregation )

35
Q

What is segregation of zygote and how do the cells communicate

A
  • when the blastomeres maximize contact and form a compact ball
  • inner and outer cells communicate by gap junctions
36
Q

When and how is morula formed and its components at early stages

A

-3 days after fertilization embryo divides into 16 or cells called morula

  • inner cell mass : embryoblast
  • outer cell mass : trophoblast
37
Q

When and how is blastocyst formed

A
  • when morula enters uterine lumen
  • fluid penetrates zona and accumulates at intercellular spaces which join to form single cavity called blastocele
  • outer cells flatten and form wall of epi
  • zona disappears preparing for implantation
38
Q

The layers of uterus describe structure and where found

A

1 endometrium - innermost layer mucosal lining

2 myometrium - middle smooth muscle layer

3 perimetrium - outer peritoneal covering

39
Q

How many days will uterus undergo changes

List the stages

A

-28

  • follicular
  • proliferative / progestational
  • menstrual
40
Q

What occurs and uterine proliferative stage and when does it begin and what mediates the process

A
  • at the end of menstrual phase
  • day 14
  • under influence of estrogens
41
Q

What occurs and uterine progestational / secretory stage and when does it begin and what mediates the process

How does Gravid stage occur

A
  • 2 to 3 days after ovulation in response to progesterone from corpus luteum
  • day 14-21

-if egg implanted

42
Q

What happens to endometrium if egg fertilized or not

A
  • assist in implantation and contributes to placenta formation
  • shedding of cortical and spongy. Marks beginning of menstrual phase
43
Q

List the layers of the endometrium and functions and locations

A

1 basal. Bottom layer from where blood vessels and other layers regenerate from

2 spongy layer - inner layer

3 cortical layer - outer most layer of endometrium

44
Q

List and describe the events of 1st week and the hours

A 
1 oocyte ovulated 0
2 fertilization 12-24 hours after ovulation 
3 male and female pronuclei grow and replicate 
4 spindle of 1st mitotic division 
5 2 cell stage 30 hours 
6 morula forms 3 days after ovulation 
7 Advanced morula reached uterine lumen 
8 early blastocyst formed 4.5 days 
9 early phase of implantation 6 days
45
Q

What phase is mucosal lining at time if implantation and describe the tissue at this time

A
  • secretory phase

- arteries and glands coiled and tissue is succulent

46
Q

Where does blastocyst implant

A

-along anterior posterior wall of body of uterus between openings of glands

47
Q

What happens to endometrium if egg not fertilized

What occurs during mensturation

A
  • venules and sinusoidal spaces fill with blood and extensive diapedesis of blood into tissue is seen
  • blood escapes from superficial arteries and small pieces of stroma and gland break away and for the next 3-5 days compact and spongy layer is expelled from uterus but basal layer remains

Embryology (5 decks)

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