lecture 19, the female reproductive system

the female gonads are

• ovaries

• located in the pelvic cavity on either the uterus

• responsible for production of gamete

each ovary consists of 4 layers

1. superficial epithelium (mesothelium)

   • simple cuboidal

   • on surface, wallpaper

2. tunica albuginea

   • dense irregular connective tissue

   • helps the epithelium bind

3. ovarian cortex

   • outer layer of the ovary

   • contains ovarian follicles

   • all the follicles are developed here

4. ovarian medulla (internal)

   • the center area of the ovary

   • contains blood vessels, lymph vessels

   • need nerves too

   • living structure

membranes that support the ovary include

1. mesovarium: suspends the ovary between the uterus (medial) and the pelvic wall (lateral)

2. suspensory ligament: anchors the ovary to the pelvic wall

3. the ovarian ligament: attaches the ovary to the uterus

   • 1 and 2 are part of the broad ligament

     • tents over the uterus supporting the uterine tubes, uterus, and vagina

       • made from peritoneum

     • holding things so they don’t wall

oogenesis

• refers to the production of gametes within the follicles ovary

• oogonia (2n cells)

  • mitosis

• primary oocytes (2n cells), present in the ovary at birth

  • meiosis I: is completed once per month at puberty

    • the others stay quiet

    • they are there since birth

• 1x secondary oocyte (n cell) + 1x polar body (n cell) which is discarded

  • structures is ovulated and meiosis II completes following fertilization

  • 1 haploid gets to proceed

  • putting recycled material elsewhere

  • wont complete meiosis II if there is no fertilization

• 1x ovum (n cell) +1x polar body (n cell) which is discarded (still haploid)

• one primary oocyte will give rise to one ovum and two polar bodies

  • polar bodies are the ‘waste’ of the process and are broken down

stages of oogonia/oocyte development (1-2)

1. first oogonia appear in females 11 weeks post-fertilization

   • the oogonia begin to undergo mitosis → 2n cells

   • the oogonia differentiate into primary oocytes → 2 n cells (increase the number)

   • building a human

   • diploid cells that will undergo mitosis

2. there are up to 2 million primary oocytes in the ovaries at bith

   • these are the total number of oocytes that will ever be present in a female

     • new oocytes will never form

   • the primary oocyte is surrounded by a follicle which support and protects the oocyte

     • you support it for reproductive process

   • the primary oocyte enter into meiosis I wait in prophase I until puberty begins

     • at puberty one primary oocyte will undergo meiosis I per month

       • this produces one secondary oocyte (n) and one polar body (n) which will be discarded (now haploid)

       • follicle stimulating hormone (FSH) is needed for this development to occur (encourages development)

stages of oogenesis (2-3)

3. secondary oocyte (n)

   • begins meiosis II and stops in metaphase II

   • it is this form of the egg that is released during ovulation each month

   • there are enough secondary oocytes to provide for ~500 ovulations in a woman’s lifetime

   • if fertilization, then meiosis II is complete

   • sister chromosomes not pulled apart yet

   • go past prophase II

4. fertilization

   • this process takes ~24 hours

   • it begins with fusion of the sperm and the secondary oocyte

     • trigger

     • metaphase II and on needs to complete

   • once fusion occurs the secondary oocyte undergoes meiosis II forming the ovum

   • the nuclei of the sperm and the ovum fuse following the completion of meiosis II generating zygote

     • have a nucleus that is now diploid

     • mitotic divisions now

ovarian follicles (1-3)

• located in the cortex of the ovary (big space)

  1. primordial follicles

     • preset in the ovary at birth

     • the primary oocyte is surrounded by a single layer of flat follicular cells

  2. primary follicles

     • stratified layer of cells (lots of cell present)

     • single layer called the granulosa proliferates under the influence f FSH forming the zona pellucida (immediately around oocyte)

     • the surrounding tissue forms theca cells

     • the primary follicle contains the primary oocyte is present in childhood

  3. secondary follicles

     • located in the ovaries during puberty (~250,000 oocyte remain at puberty)

     • the primary oocyte undergoes meiosis I becoming the secondary oocyte at puberty

     • the granulosa and theca cells begin secreting estrogen

     • antrum → fluid filled structure, gets bigger and bigger

ovarian follicles (step 4)

4. Graafian follicles (mature secondary follicles)

• small fluid-filled sacs merge forming a fluid filled cavity in the follicle called the antrum

  • this structure moves closer to the ovary surface

• the corona radiata is the layer of granulosa cells that immediately surround the oocyte

  • it is this structure that will be ovulated

• rising levels of estrogen produced by the follicle trigger an increase in luteinizing hormone (LH)

  • the increasing level of LH trigger the completion of meiosis I generating a secondary oocyte → arrests at the beginning of metaphase II (went through meiosis I)

  • the LH surge also triggers ovulation

    • the Graafian follicle bursts and release the secondary oocyte into the peritoneal cavity

    • the ovulated oocyte consists of the oocyte, the zona pellucida and the corona radiata

ovulation

• the Graafian follicle remains in the vary without its contents

  • becomes corpus luteum (estrogen will be kept as endocrine tissue)

    • endocrine tissue

    • when it bursts, rest stays

• the central space of the follicle fills with blood and clots

• the corpus luteum forms from proliferation of the granulosa and theca cells

  • the corpus luteum functions to produce estrogen and progesterone

    • if it drops can cause the pregnancy to terminate

  • if fertilization does not occur the corpus luteum disintegrates and becomes the corpus albicans (left over of follicle after ovulation)

    • estrogen and progesterone secretion halts resulting in the beginning of a new cycle

    • source of hormones drop

    • can count the scar tissue to see how many time one has ovulated

fallopian tubes

• also called the uterine tubes

• consist of the

  1. infundibulum

     • contains fimbriae

     • suspend over the ovary

  2. ampulla

     • this is the middle 2/3 of the fallopian tubes

     • where fertilization should happen

  3. isthmus

     • the portion of the fallopian tube that connects to the uterus

• fallopian tube does not contact ovary

fallopian tube histology

1. the mucosa

   • consists of ciliated simple columnar epithelium

   • cilia assist in the movement of the oocyte along the length of the fallopian tube

   • there is also non-ciliated columnar epithelial (elongated cells) cells called peg cells → contain microvilli (important for secretions → gives nutrients to oocyte)

     • secretes a nutrient rich fluid

2. the mucularis externa

   • smooth muscle (involuntary)

   • assists in the movement of the oocyte along the length of the tube with rhythmic contractions

3. serous membrane

   • visceral peritoneum

   • adventitia (out of peritoneum)

   • low in the abdomen

uterus

• is attached to the abdominal wall by supportive membranes (if not suspended it will collapse)

  1. broad ligament

     • portion of the parietal peritoneum (extension)

       • sheets that drapes over everything

     • suspends the uterus laterally

  2. round ligament

     • composed of fibrous connective tissue (anterior surface)

     • attaches the uterus to the anterior wall of the body

  3. the uterosacral ligament

     • portion of the peritoneum

     • attaches the uterus to the sacrum

     • posterior

the uterus is a hollow organ consisting of the

• fundus which is higher than the fallopian tube level

• body which is the major portion of the uterus

• cervix which is the inferior, narrow portion of the uterus that opens into the vagina (plug comes out)

• the uterine cavity is the space in the body that houses the uterus

histology of the uterus

• consists of 3 layers

  1. the outer peritoneum

     • the visceral peritoneum → simple squamous epithelium

     • a serous membrane

  2. the myometrium

     • composed of the muscularis externa → smooth muscle

     • three layers total

  3. the endometrium

     • mucous membrane → open to outside

     • consists if simple columnar epithelium

       • endometrial glands (secretions to support growing a human)

       • thick lamina propria connective tissue

       • two layers

         1. stratum functionalist: located nearest to the uterine cavity

            • shed during menstruation (thicker and thicker, trying to create fresh bearing)

         2. stratum basalis: permanent layer that gives rise to a new stratum functionalism after mensuration → mitosis

the vagina

• functions as the

  • birth canal

  • site of sperm deposition and transport

  • exit for menstrual flow

  • naturally mean to happen

• contains

  1. mucosa

     • stratified squamous epithelium and connective tissue (for abrasion of baby or penis)

     • rugae to stimulate the penis and allow for expansion of the vaginal cavity

  2. a muscularis layer

     • two layers of smooth muscle

     • facilitates stretching during childbirth and intercourse

       • elastic

  3. adventitia

     • areolar connective tissue (covering)

external genitalia

• the labia majora has the same origin as the scrotum in the male (just doesn’t drop out)

• the labia minora has the same origin as the male penis

• the clitoris has the same origin as the erectile tissue of the male penis (fills with blood, vascularity)

the mammary glands

• each breast contains one mammary gland

• mammary glands are modified sudoriferous glands that secrete milk

• contain small compartments called lobules

  • lobules contain milk secreting glands called alveoli (connect to central canal)

• milk produced in the alveoli move through the lactiferous ducts which open into the nipples

  • sucking is high to low pressure

• the breast lie over top of the pectorals major and the serratus anterior muscles

• each breast is attached to the epimysium of the muscle below by sensory ligaments called Cooper’s ligaments

  • not strong, loose, saggy