11.10 Histology of the Female Reproductive System Flashcards Preview

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Flashcards in 11.10 Histology of the Female Reproductive System Deck (51):
1

What are the major functions of the ovaries?

  • Produces gametes
  • Produces hormones (it is an endocrine organ)
  • Responsive to circulating hormones

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2

Describe the location of the ovaries

They are 2 bilaterally placed on either side of the superior aspect of the uterus/fallopian tubes. 

They are attached to the posterior face of the broad ligament. 

They are anchored by an ovarian ligament (to uterus) and suspensory ligament (to pelvic wall)

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3

Are the ovaries physically attached (in direct contact) with the fallopian tubes?

No. 

 

The ovaries are in very close proximity to the fallopian tube (fimbrae)

4

Describe the structure of the ovary

Divided (hard to see) into...

  • Inner medulla
    • highly cellular loose connective tissue
    • highly vascularised vessels
    •  scattered smooth muscle cells
  • Outer cortex
    • less blood vessels,
    • location of ovarian follicles – oocytes of varying maturities

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5

Is the surface of the ovary smooth or roughened?

Why is this so?

The surface is irregular.

Scarring from release of oocytes from the surface

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6

Describe the outer surface of the ovary

 

70% of ovarian tumours are from this epithelium

Surface is a simple epithelium (squamous or cuboidal) continuous with mesothelium.

 

The mesothelium surrounding the ovary is also shared with the broad ligament and the others covering the structures of the cavity 

7

What layer is underneath the surface epithelium of the ovary? 

What does this layer contain?

Tunica albuginea

  • All of the oocytes
  • Dense connective tissue
  • Smooth muscle cells

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8

What is the change in oocyte numbers in the ovaries from foetal life through to death?

  • 5 million per ovary in embryo
  • 0.5 million by birth
  • Most degenerate over life
  • A few thousand go through most of a maturation cycle and around 500 are released into the fallopian tube
  • These run out at the point of menstruation

9

Describe the lifecycle of one oocyte through the maturation stages

  1. Oogonium
  2. Primordial oocyte (present in the foetus)
  3. Primary oocyte (arrested in first meiosis)
  4. Secondary follicle 
  5. Graafian follicle (mature follicle)
  6. Secondary oocyte
  7. Mature ovum (upon fertilisation)

10

Describe the primordial oocyte

  • What are formed in the embryo
  • Smallest oocytes
  • On outside they are surrounded by squamous follicle cells.
    • The follicle cells provide the microenvironment required
  • These cells are surrounded by a common basal lamina that holds it all together
  • Oocyte is arrested in prophase of meiosis 1 (incomplete meiotic division)

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11

Describe the primary oocyte

  • Oocyte now surrounded by zona pellucida (within follicle cell layer)
  • Oocyte enlarges, follicular cells become cuboidal and multilayered granulosa cells (form stratum granulosum)
  • Surrounding stromal cells start to form theca interna and externa (surround stratum granulosum)

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12

Describe the seconday follicle 

Is this the same as the secondary oocyte?

  • The stratum granulosum thickens (proliferation)
  • Fluid filled cavity (antrum) appears
  • The oocyte is suspended on a stalk of granulosa cells (cumulus oophorus)
  • A small number of granulosa cells directly surround the oocyte (corona radiata)

 

This is not a secondary oocyte. Just the primary oocyte that has had the environment directly around it changing.

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13

What is the mature follicle called? How big is it?

 

Graafian follicle (10 mm diam.)

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14

What happens to the Graafian follicle in ovulation

Eventually the antral cavity ruptures and this rupture extends to the external surface of the overy such that the oocyte is released from the antrum and the ovary.

The oocyte still has the surrounding of the remains of the granulosa called the corona radiata

15

High levels of oestrogen stimulate an LH and FSH surge. What does this signal?

Under LH surge, oocyte completes first meiotic division (started years before) = secondary oocyte (within the Graafian follicle)

 

Then ovulation occurs = the follicle ruptures

 

The Oocyte is released into body cavity and can enter fallopian tube – lasts 24 h if not fertilised

16

What happens to the remainder of the Graafian follicle once the oocyte has been released?

Once follicle loses oocyte, it forms corpus luteum

 

Stromal, granulosa and thecal cells invade and fill it up so it becomes a solid mass: causing a differentiatiation into luteal cells

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17

The corpus luteum matures to become high vascularised and contain high amounts of lipid (yellow appareance). 

What is the significance of the lipid content?

Lipid (cholesterol) forms the basis of the steroidogenic nature of the corpus luteum. It uses lipid content to produce steroid hormones: progesterone and estrogen to prepare endometrium

18

The corpus luteum lasts until the placenta is able to take over. 

How long does the corpus luteum last for if there is no pregnancy?

Lasts 14 days, if no fertilisation becomes corpus albicans and involutes with time

19

What is the fallopian tube?

What are the major functions?

(Uterine tubes)

  • Unite sperm and egg
  • Provide environment for fertilisation and initial development
  • The opening (fimbrae) collects released oocytes

20

What aids the fallopian tube's ability to collect the egg from the pelvic cavity once the ovary has expelled it? [3]

  • Finger like structures on the infundibular opening (fimbraie)
  • Cilia lining the tube helps to beat the ooctye along
  • A gentle flow of fluid flows into the fallopian tube in the direction of the uterus

21

Describe the structure of the fallopian tube

Microscopically and Macroscopically

Microscopic:

Has serosa (mesothelium plus thin connective tissue layer), smooth muscle muscularis and mucosa (connective tissue plus epithelium)

Macroscopic:

  • Widest at the end near the ampulla (the end of the infundibulum attaching the fimbriae): thin wall epithelium that is ciliated and extensive secretory mucosa for support)
  • Narrows down into the isthmus (less extensive mucosa but a stronger muscular wall to get a slight peristalsis to push the egg along to the uterus) 

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22

What are four key characteristics of the fallopian/uterine tube?

  • Epithelium is ciliated. Moves oocyte towards isthmus
  • Peristalsis helps
  • Fluid secreted by epithelium provides nutrients for oocyte
  • Fertilisation usually occurs in ampulla, zygote remains for three days in isthmus

23

What are the [3] major functions of the uterus?

  • Blastocyst implants into wall of uterus
  • Uterus is muscular sac with elaborate epithelium: 
    • Thick smooth muscle wall (myometrium) to expel baby. 
  • Provides site of development of embryo and fetus

24

What are the 3 layers of the uterine wall?

Divided into a mucosa (endometrium), muscularis (myometrium)

An outer perimetrium covers most of the external surface and consists of mesothelium and underlying elastic connective tissue

25

What is special about the endometrium and the myometrium in terms of endocrine function

Myometrium and endometrium respond to cyclic hormonal changes that drive menstrual cycle

 

The uterus is a Dynamic organ w/ cycles of building and destruction

26

Describe the myometrium of the uterus

Three layers of smooth muscle

  1. Inner longitudinal
  2. Outer longitudinal
  3. Middle is circular and very vascular

Uterine muscle is very plastic and accommodates pregnancy by enlarging individual smooth muscle cells, generating more smooth muscle cells and increasing connective tissue

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27

Once a baby is born, does the uterus regress back to its original size?

No

Thickened wall retained after first pregnancy, it does shrink back down but not to the same relative to what it was prior to any pregnancy

28

Describe the epithelium of the endometrium of the uterus

  • Epithelium - ciliated and secretory columnar cells in simple epithelium

  • Epithelium folds down from the surface into long tubular glands extending down the length of the mucosa to the muscle layer. Ciliated cells are not in the glands (only secretory cells present)

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29

Describe the secretory apparatus of the endometrium of the uterus

Secretory glands (no ciliated cells) penetrate into lamina propria

The endometrial stroma is..

  • highly cellular
  • rich in ground substance and reticular fibres
  • not very fibrous
  • like mesenchyme embryonic connective tissue

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30

The mucosa of the uterine endothelial layer is unique.

Describe the structure and the significance of it

Unique vasculature, penetration from muscular layer and take a helical artery (spiral fashion) structure to allow expansion of the layer w/o stretching blood vessels

 

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31

The endometrium is a functional layer sloughed off each menstrual cycle

What is left behind?

The whole thing is sloughed off except for the basal layer.

Basal layer regenerates functional layer

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32

How does the endometrium change with the menstrual cycle?

  • Endometrium changes thickness during cycle
  • Growth is driven by estrogen initially and breakdown by later decrease of estrogen and progesterone
  • Fertilisation maintains corpus luteum and progesterone and estrogen levels

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33

Describe the histological changes that occur in the three major stages of the endometrium:

  • Early proliferative
  • Proliferative
  • Secretory

Epithelial, stromal (lamina propria) and vascular cells proliferate vigorously

  • Early proliferative: Prominent glands marks this stage of growth.
  • Proliferative: Glands are more prominent w/ large lumen. Straight glands and mitotic figures with high basophilic cells. 
  • Secretory: can see the lumen of the glands full of fluid. Tortuous glands and clear glycogen spaces in the cells

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34

Describe the fluid secreted by the glands of the endometrium

Thick product that sustains the fertilised egg as it drifts into the uterus and implants

  • Mucoid fluid
  • High glycogen

35

What is the cervix

Narrow connection between uterus and vagina

36

What are the two parts of the cervix?

Describe the histological features of each

Endocervix (Uterine cervix)

  • Simple columnar epithelium
  • Glandular (cervical glands)
  • Secretion is serous and copious at ovulation, thick and plug like at other times

 

Ectocervic (Vaginal cevix)

  • Stratified squamous epithelium - protection from pathogens
  • Non-glandular (kept dry)

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37

Desribe the Squamo-columnar junction of the cervix

  • Transition between simple columnar and stratified squamous epithelium is abrupt
  • Location of boundary varies between reproductive and non-reproductive females and with stage of menstrual cycle
  • Stratified epithelium sheds cells

 

Constant turnover of cells makes this area predisposed to cancerous change

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38

Describe the histology of the vagina (a fibromuscular tube)

  • Stratified squamous non-keratinizing epithelium (undergoes cyclic changes with menstrual cycle) and forms mucosa with partly erectile lamina propria (Can be engorged with blood to stiffen it and change its shape)
  • Smooth muscle layers, thin inner and thick outer layer (continuous with muscle of uterus)
  • No glands. Lubricated by cervical glands or glands in vestibule

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39

Do the shapes and functions of breasts stay constant throughout life?

Breasts vary with age, menstrual cycle or reproductive status

Very responsive to hormonal state

40

Describe the structure of the breast

  • Multiple mammary glands each opening in a common place: on nipple through separate openings
  • The glands are embedded in dense connective tissue
  • There is abundant adipose tissue (Bulk of the breast tissue. Spares space of mammary tissue (fills everything else))

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41

Describe breast development 

  • Until puberty, male and female mammary glands similar
  • At puberty, male glands regress (testosterone) and female glands grow (estrogen and progesterone)
  • Glands extend and breast enlarges (mainly extra adipose tissue)
  • Glands inactive until pregnancy (under negative influence of stromal cells

42

Why can males get breast cancer?

Until puberty, male and female mammary glands similar

In males, the cells are held in a quiescent state (can still get breast cancer because the cell types are still present)

43

Describe the structure of the Mammary Glands

  • Modified sweat glands
  • 15-20 lobes (separate glands) in a typical breast
  • Lactiferous ducts form a branching network and end in terminal duct lobular units (TDLUs)
    • TDLUs made up interlobular collecting ducts and terminal ductules or acini
    • Surrounding intralobular stromal tissue free of adipose tissue and responsive to hormones

44

Are inactive glands responsive to the menstrual cycle?

Yes they are (despite them not being active and producing milk)

  • In follicular stage, stroma is less dense, lumen of each gland invisible and surrounded by cuboidal epithelial cells
  • In luteal phase, epithelial cells more columnar, some secretions (lumens appear), fluid accumulates in stroma connective tissue
  • Just before and during menstruation, gland involutes and some cells apoptose

45

Describe the histology of an inactive mammary gland

Glands are relatively sparce, cuboidal/columnar epithelial cells, surrounding myoepithelial cells in extensive dense connective tissue

 

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46

Describe the activation of the mammary glands (in pregnancy)

  • Dramatic response to new hormone levels
  • Terminal ductules elongate and branch
  • Epithelial and myoepithelial cells proliferate from progenitor cells
  • By term, have large cuboidal epithelial cells containing lipid and secretory product in lumen
  • Breast is enlarged as a result of growth: Increased mass of mammary tissue and accumulation of fluid

47

Describe the histology of active mammary glands

Proportion of gland that is secretory becomes the majority and only small areas of CT in between

 

Ducts are inflated and can see milk forming inside

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48

Milk is a complex secretion. What is in it?

  • Mixture of lipid, carbohydrate, protein
  • Initially colostrum (premilk)
    • Low in fat, high in protein. Massive dose of IgA 
    • Later milk is high in fat and CHO
  • High protein, low lipid and carbohydrate
  • High in IgA (from plasma cells that have invaded intralobular connective tissue)
  • IgA provides passive immunity
  • Prolactin stimulates milk production

49

Lactation is a reflex response, often to lactation (sometimes to the sound of crying babies). 

Describe this reflex

  • Suckling initiates a reflex that inhibits prolactin release-inhibiting hormone in hypothalamus (pituitary prolactin release increased)
  • Also releases oxytocin. Acts on myoepithelial cells – epithelial cells with actin and myosin
  • Squeeze TDLUs and lactiferous sinuses to release milk

50

What are the myoepithelial cells of the breast?

  • There are sinuses on lactiferous ducts store milk
  • Myoepithelial cells form network around sinuses and secretory cells
  • This is a reticulated network: myoepithelial cells w/ myosin and actin in them. Contraction puts pressure on cells within them (secretory cells and the ducts) causing a surge of milk

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51

What is the involution of mammary glands?

When does this occur?

  • Secretory cells disappear leaving only duct system
  • Connective tissue changes, losing elastic and collagen fibres and fibroblasts

 

Occurs following menopause