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Human Development > Microanatomy 2 > Flashcards

Microanatomy 2 Flashcards

1
Q

what are the two important functions of the ovaries

A
  1. the production of female gametes

2. the secretion of hormones

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2
Q

what do the embryonic gonads contain

A
  • they contain primordial germ cells
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3
Q

what do the female primordial germ cells become

A
  • they undergo mitosis to form oogonia
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4
Q

what happens to the oogonia in the 5th month of fatal development

A
  • they enlarge and divide becoming primary oocytes

- primary oocytes begin there first meiosis by this stage

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5
Q

what happens in the 7th month of fatal development to primary oocytes

A
  • the primary oocytes become surrounded by a layer of flattened cells and become known as primordial follicles
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6
Q

what does the process of encapsulation do

A
  • the process of encapsulation of the primmer oocyte blocks the first meiotic division of the primordial follicle in the prophase
  • no further development of the follicle occurs until puberty
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7
Q

what does each oogonia give rise to

A

one oocyte and three polar bodies

-

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8
Q

what does one spermatogonium give rise to

A

4 spermatozoa

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9
Q

describe Male gamete development versus female gamete development

A

female
- all germ cells are present at both but meiosis I only is completely during follicular maturation in the lead up to ovulation

ale
- meiosis I occurs after puberty and the whole process of spmeratogensis and spermiogensis takes about 17 days

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10
Q

how many follicles are activated during each ovarian cycle

A
  • up to 20 primordial follicles are activated
  • only one growing follicle reaches full maturity and undergoes ovulation
  • the rest undergo atresia
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11
Q

what is atresia

A

the degerenation or regress of follicles

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12
Q

what are the three phases of the ovarian cycle

A
  • follicular phase
  • ovulatory phase
  • luteal phase
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13
Q

describe the three phases of the ovarian cycle

A

Follicular phase - from follicles that start developing, one mature, Graafian follicle developments

ovulatory phase - the Graafian follicle ruptures and releases the secondary oocyte and surrounding granulosa cells

luteal phase - the endocrine structure of the corpus lute develops, it eventually degenerates leaving the Corpus albicans

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14
Q

what are the stages of the follicular phase of the ovarian cycle

A
  • primary follicle stage
  • growing follicle stage
  • secondary astral follicle stage
  • Graafian follicle stage
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15
Q

describe what happens in the primary follicle stage

A
  • the primordial follicles have been stimulated to develop and increase in size
  • each oocyte gets larger and the cells of the surrounding follicular epithelium multiply and change from simple squamous to cuboidal
  • they are now grnaulcoa cells
  • a thick glycprotien and acid proteoglycan layer called the zone pellucid is formed between the oocyte and grnaulosa cells
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16
Q

what is the layer between the granulose cells and oocyte

A

zona pellucida

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17
Q

What epithelium is the ovary surrounded by

A
  • it is surrounded by a cuboidal to columnar germinal epithelium
  • continuous with the mesothelial cells of the mesovarium
  • underlying the germinal epitheilium is a fibrous layer, this is the tunica albugiunia
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18
Q

what does stroma mean

A
  • this is a general term we use for the supporting tissue which here is rich in fibroblast like cells
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19
Q

where are the primordial germ cells produced

A
  • they arise in the embryonic yolk sac and migrate to the embryonic gonads
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20
Q

what happens in the growing follicle stage of the follicular phase of the ovarian cycle

A
  • the granulose cells form a multilayered capsule around the oocyte this is a zone granulose
  • the storm around the follicle starts to organise into theca colliculi
  • theca cells produce androgens which are then aromatised in the grnaulosa cells to yield estranges which they secrete
  • ## most growing follicles will undergo atresia and die
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21
Q

what happens in the secondary (astral follicle) stage in the follicular phase in the ovarian cycle

A
  • remaining follicles take up fluid and develops a fluid filled cavity called the follicular antrum with the oocyte embedded on one side in the zone granulosa cells, the cumulus oophorus
  • the surrounding theca organises into the theca internal that continues to secrete androgen precursors and the theca externa - a capsules like layer
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22
Q

what happens in the Graafian follicle stage in the follicular phase in the ovarian cycle

A
  • the first meiotic division is completely just before ovulation
  • antrum continues to enlarge and forms a layer of granulose cells also called the zone granulosa - which lines the entire follicle
  • the oocyte now called a secondary oocyte is attached to the side by bridges of grnaulosa cells and is surrounded by a layer of granulosa cells a few cells thick called the corona radiate
  • the follicle is so large it bulges from the side of the ovary
23
Q

describe how the follicular phase of the ovarian cycle takes place

A

primary follicle stage
the primordial follicles have been stimulated to develop and increase in size
- each oocyte gets larger and the cells of the surrounding follicular epithelium multiply and change from simple squamous to cuboidal
- they are now grnaulcoa cells
- a thick glycprotien and acid proteoglycan layer called the zone pellucid is formed between the oocyte and grnaulosa cells

growing follicle stage

  • the granulose cells form a multilayered capsule around the oocyte this is a zone granulose
  • the storm around the follicle starts to organise into theca colliculi
  • theca cells produce androgens which are then aromatised in the grnaulosa cells to yield estranges which they secrete
  • most growing follicles will undergo atresia and die

secondary astral follicle stage

  • remaining follicles take up fluid and develops a fluid filled cavity called the follicular antrum with the oocyte embedded on one side in the zone granulosa cells, the cumulus oophorus
  • the surrounding theca organises into the theca internal that continues to secrete androgen precursors and the theca externa - a capsules like layer

Graafian follicle stage

  • the first meiotic division is completely just before ovulation
  • antrum continues to enlarge and forms a layer of granulose cells also called the zone granulosa - which lines the entire follicle
  • the oocyte now called a secondary oocyte is attached to the side by bridges of grnaulosa cells and is surrounded by a layer of granulosa cells a few cells thick called the corona radiate
  • the follicle is so large it bulges from the side of the ovary
24
Q

what happens in the ovulatory phase of the ovarian cycle

A
  • the ovarian wall thins next to the mature Graafian follicle and ruptures expelling the ovum into the peritoneal cavity
  • the ovum is comprised of the secondary oocyte, the zone pellucid, and corona radiant of the granulose cells
  • the second meiotic division only occurs following penetration of the ovum by a spermatozoon
25
Q

what is the ovum comprised of

A
  • the ovum is comprised of the secondary oocyte, the zone pellucid, and corona radiant of the granulose cells
26
Q

when does the second meiotic division occur

A
  • the second meiotic division only occurs following penetration of the ovum by a spmeratozoon
27
Q

what happens in the luteal phase of the ovarian cycle

A
  • after ovulation the grnaulsoa cells together with the theca cells of the Graafian follicle proliferate and form the corpus lutem
  • the corpus lutem secretes progesterones and oestrogen’s
  • progesterones prepare the endometrium of the uterus for implantation of a fertilised ovum
  • if fertilisation does not occur than the corpus luteum degernated and leaves the corpus albicans
  • if implantation occurs the developing placenta secretes HCG this maintains the corpus luteum and thus maintains progesterone
  • after about the 12th week of pregnancy the placenta takes over the production of progesterone and forms the corpus luteum which degernates and forms a corpus albicans
28
Q

what does the corpus luteum secrete

A

progesterones and estrogens

29
Q

what produces progesterone after the 12th week of pregnancy

A
  • after about the 12th week of pregnancy the placenta takes over the production of progesterone and forms the corpus luteum which degernates and forms a corpus albicans
30
Q

describe the structure of the corpus luteum

A
  • zona granulose cells of the Graafian follicle increase dramatically in size and start secreting progesterone - these are called the grnaulsoa lutein cells in the corpus luteum
  • the theca lutein cells are derived from the theca internal cells and continue producing mainly androgens
  • connective tissue septa carry blood vessels into the structure
  • while estrange continues having a role in maintaining the uterine mucosa, progesterone promotes secretion from the glands in the mucosa which provides a suitable environment for a fertilised ovum to implant
31
Q

what does the corpus luteum form on degernation

A

forms a fibrous scar called the corpus albicans

32
Q

what causes development of ovarian follicles

A

FSH

LH

33
Q

what causes FSH and LH to be released

A

GnRH

34
Q

what produces oestrogen

A
  • growing follicle
35
Q

what do rising levels of oestrogen do

A
  • with rising levels of oestrogen and inhibin production his causes negative feedback to the hypothalamus and pituitary inhibiting FSH and lH release
  • but when oestrogen rises beyond a certain level it imitates a positive feedback loop and this results in a s surge of LH and to a lesser extent FSH secretion
36
Q

what does the surge of LH lead to

A

this l leads to the completion of meiosis I of the oocyte and the production of enzymes that weaken the ovary wall leading to ovulation

37
Q

what does LH do after ovulation

A
  • it promotes the transformation of the ruptured Graafian follicle into the corpus luteum
38
Q

what does the corpus luteum produce and what does this do

A
  • it produces progesterone, oestrogen and inhibin

- this acts to inhibit FSH and LH secretion and thus the development of further follicles

39
Q

what happens when LH decreases

A
  • the corpus luteum starts to degenerate
  • oestrogen and progesterone levels fall
  • this allows FSH and LH to be produced by the pituitary glands and the cycle starts again
40
Q

What makes up the uterus

A
  • Fallopian tube
  • fundus (body)
  • cervix
41
Q

what is the menstrual cycle

A
  • the hormonal changes that cause changes in the endometrium of the uterus
42
Q

what are the three stages of the menstrual cycle

A 
menstrual phase (1-5)
proliferative phase (6-14)
secretory phase (15-28)
43
Q

what is the myometrium

A

this is the muscle layer of the uterus which is called the myometrium

44
Q

describe the structure of the myometrium

A
  • fascicles of muscle fibres run in different directions forming ill defined layers
  • contains a rich network of arteries and veins supported by dense fibrocoallgenous tissue
45
Q

what happens to the myometrium during pregnancy

A
  • it increases greatly in size in response to the oestrogen’s
  • this increase in mass is due to the hypertrophy of the smooth muscle cells but increased cell number also plays a role
46
Q

what does the fallopian tube do

A
  • it connects the ovum to the uterine cavity
47
Q

describe the structure of the Fallopian tube

A
  • has fimbria - these envelop the ovary at ovulation to direct the ovum into the tube
  • vili line the tube which helps propel the ovum through the tube
  • fertilisation occurs in the ampulla
48
Q

what are the 3 parts of the Fallopian tube

A
  • isthmus
  • ampulla
  • infundibiulm
49
Q

describe the structure of the ampulla of the Fallopian tube

A
  • it has a folded mucosal lining tissue
  • this provide a secretory product this protects and nourishes the ovum and provides a suitable environment for its fertilisation
50
Q

describe the structure of the cervix

A
  • endocervical canal - this links the vagina body to the uterus
  • folded mucosa
  • lined by simple columnar epithelial cells that make a mucous secretion
  • at the external os the endocergical mucosal epithelium is exposed to more hostile acidic vagina environment and thus changes into the stratified squamous epithelium from simple columnar this is called the ectocervix
51
Q

what is the function of the cervix

A
  • the role of the cervix is to admit serpmatozoa to allow fertilisation of the ovum around the time of ovulation
  • and to protect the upper parts of the tract from bacteria invasion
52
Q

why does the ectocervix undergo changes in epithelium

A
  • at the external os the endocervical mucosal epithelium is exposed to more hostile acidic vagina environment and thus changes into the stratified squamous epithelium from simple columnar this is called the ectocervix
53
Q

describe the structure of the vagina

A
  • fibromuscular canal
  • lined with a mucosal stratified squamous epithelium
  • dense lamina propria has many elastic fibres and a rich vasculature
  • lubrication of the mucosa is from a cervical mucus and a transepithelial exudate from thin walled vessels in the lamina propria
  • around the muscular layer there is the connective tissue adventitia this is not located in the peritoneal cavity and thus is not lined by mesothelium
  • this connective tissue merges with the adventitia of the bladder anteriorly and the rectum posteriorly
54
Q

where does the vagina produce lubiication

A

lubrication of the mucosa is from a cervical mucus and a transepithelial exudate from thin walled vessels in the lamina propria

Human Development (28 decks)

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