Female reproductive syste m

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Female reproductive system


Female Reproductive Anatomy Ovaries are the primary female reproductive organs

Make female gametes (ova) Secrete female sex hormones (estrogen and

progesterone) Accessory ducts include uterine tubes, uterus, and

vagina External genitalia – external sex organs


Female Reproductive system anatomy


Ovaries Ovaries contain the ovarian follicles Each follicle consists of an immature egg (oocyte) Cells around the oocyte are called:

Follicle cells (one cell layer thick) Granulosa and theca cells (when more than one

layer is present) The follicles and the oocytes are going through

cyclic development – ovarian cycle


Combination of follicles and oocyte development Divided to 2 major periods (phases)

Follicular phase – period of follicle growth (days 1–14) Luteal phase – period of corpus luteum activity (days 14–

28) The 2 phases are “separated” by Ovulation (release of the

secondary oocyte from a tertiary follicle)

The ovarian cycle


Follicular phase Luteal phaseovulation

http://biology.clc.uc.edu/courses/bio105/sexual.htm


Follicular development - Folliculogenesis The folliculogenesis occurs during follicular phase Primordial Follicle –flattened granulosa cell layer,

basement membrane, oocyte Primary Follicle – growth of oocyte, zona pellucida

formation, cuboidal granulosa cells Secondary Follicle – add layers of granulosa cells,

formation of theca cells


Folliculogenesis Early Tertiary Follicle – antrum formation, zona

pellucida thickens, theca interna and theca externa form, basement membrane is still present between theca and granulosa cells, blood vessels are in the theca cell layer but not in follicle

Tertiary/pre-ovulatory/Graffian – full size follicle ready to ovulate; oocyte surrounded by corona radiata (granulosa cells) and attached to follicular wall by the comulus oophorus


Follicular Phase

A few follicles begin to develop from primordial follicle

Oocyte grows, granulosa cells proliferate

Zona pellucida and antrum form


Follicular Phase

Dominant follicle continues development, rest regress

Corona radiata develops Graafian follicle = mature follicle Ovulation


Luteal Phase After ovulation, the ruptured follicle collapses,

granulosa cells enlarge, and along with internal thecal cells, form the corpus luteum

The corpus luteum secretes progesterone and estrogen If pregnancy does not occur, the corpus luteum

degenerates in 10 days, leaving a scar (corpus albicans)

If pregnancy does occur, the corpus luteum produces hormones until the placenta takes over that role (at about 3 months)


Luteal Phase Ruptured follicle gland = corpus luteum Corpus luteum secretes mostly progesterone Corpus luteum reaches max activity 10 days, then

degenerates


Corpus luteum

The fate of the corpus luteum depends on fertilization:

If pregnancy does not occur, the corpus luteum

degenerates in 10 days, leaving a scar (corpus

albicans)

If pregnancy occurs, the corpus luteum produces

hormones until the placenta takes over that role (at

about 3 months)


The Ovarian Cycle


MALEFEMALE

Spermatids

develop into

MITOSISSTAGE OF CELL DIVISION

46(diploid)

Sisterchromatids

Sisterchromatids

MEIOSIS

Second meioticdivision

Secondary gamete divides.23 chromosomes

(haploid)

First meioticdivision

Primary gamete dividesinto two secondary gametes.

23 chromosomes,duplicated

Spermatogonia

Oögonium

Secondaryoocyte(egg)

Disintegrates

Secondpolar body

disintegrates.

Zygote

Sperm

Oögonia

Secondaryspermatocytes

(may notoccur)

Egg releasedfrom ovary at

ovulation.

Primaryspermatocyte

Spermatogonium

One primary spermatocyteyields 4 sperm.

One primary oocyteyields 1 egg.

Primaryoocyte

FERTILIZATION

Unfertilized eggpasses out of body.

Firstpolarbody

Germ cell proliferation

46 chromosomesper cell (only two

shown here)

DNA replicatesbut no cell division.46 chromosomes,

duplicated

Em

bryo

Em

bryoR

epro

duct

ive

adul

tR

eproductive adult

1

2

3

4

5

6

Oogenesis – oocyte development


Ovum production Occurs monthly in ovarian follicles Part of ovarian cycle Happens during the Follicular phase (preovulatory)

Oogenesis


Oogenesis Production of female sex cells by meiosis In the fetal period, oogonia (2n ovarian stem cells)

multiply by mitosis and store nutrients Primordial follicles appear as oogonia are transformed

into primary oocytes Primary oocytes begin meiosis but stall in prophase I


Oogenesis: Puberty At puberty, one activated primary oocyte produces two

haploid cells The first polar body The secondary oocyte

The secondary oocyte arrests in metaphase II and is ovulated

If fertilized, the second oocyte completes meiosis II, yielding:

One large ovum (the functional gamete) A tiny second polar body


Oogenesis


Oogonia (multiple by mitosis until 5th month of fetal development)

Arrested development (until shortly before birth)Primary oocytes (arrest in prophase I)

___________________________________________________________Puberty

Oocyte in Graafian follicle – complete meiosis I

Secondary oocyte first polar bodyArrested in metaphase II

If fertilization occur

Complete meiosis II

Ovum second polar body


Actions of Estrogens from growing follicle


Actions of Progesterone from the Corpus luteum


Uterus

Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder

Body – major portion of the uterus Fundus – rounded region superior to the entrance of the

uterine tubes Cervix – narrow neck which projects into the vagina

inferiorly Cervical canal – cavity of the cervix that communicates with:

The vagina via the external os The uterine body via the internal os


Uterine Wall Composed of three layers

Perimetrium – outermost serous layer; the visceral peritoneum

Myometrium – middle layer; smooth muscle Endometrium – mucosal lining of the uterine

cavity


Endometrium Has numerous uterine glands that change in length as

the endometrial thickness changes Stratum functionalis:

Undergoes cyclic changes in response to ovarian hormones

Is shed during menstruation Stratum basalis:

Forms a new functionalis after menstruation ends Does not respond to ovarian hormones


Uterine Tubes (Fallopian Tubes) and Oviducts Receive the ovulated oocyte and provide a site for fertilization Empty into the uterus via the isthmus Expand distally around the ovary forming the ampulla The ampulla ends in the funnel-shaped, ciliated infundibulum

containing fingerlike projections called fimbriae The uterine tubes have no contact with the ovaries Beating cilia on the fimbriae create currents to carry the oocyte

into the uterine tube The oocyte is carried toward the uterus by peristalsis and ciliary

action


Uterine tubes (Fallopian tubes or oviducts) Infundibulum

End closest to the ovary with numerous fimbriae Ampulla

The middle portion, widest and longest portion Isthmus

A short segment connected to the uterine wall The mucosa of the uterine tube has ciliated simple

columnar epithelial cells that beat toward the uterus and, with the help of muscular contractions of the tube, transmit the egg in that direction.

Fertilization occurs in uterine tube (ampulla)

The Uterine tubes


Repeating series of changes in the endometrium Menses

Degeneration of the endometrium Menstruation

Proliferative phase Restoration of the endometrium

Secretory phase Endometrial glands enlarge and accelerate their rates

of secretion

Uterine cycle


Beginning of new cycle - Menstrual Phase of the Uterus

If fertilization does not occur, the corpus luteum degenerates and estrogen and progesterone levels decrease.

The lack of estrogen and progesterone leads to the collapse of the endometrium, which in turn leads to menstruation.


Menstrual and prolifarative phases (corresponds Follicular Phase of Ovary)

FSH and LH increase during follicular phase because progesterone concentration is low and therefore negative feedback on these pituitary hormones is low.

FSH and LH stimulate primary follicles (containing primary oocytes) to grow and stimulate their theca cells to produce estrogen.

Estrogen leads to a thickening of the endometrium.


The one dominant follicle (Graafian follicle) survives because it is hyperresponsive to FSH and can maintain itself

even under low FSH it also becomes sensitive to LH.

LH surge appears because increased estrogen exerts a positive feedback effect on the LH releasing mechanism of pituitary.

LH surge leads to release of the primary oocyte (ovulation)

Menstrual and prolifarative phases (corresponds Follicular Phase of Ovary)


Secretory Phase of the Uterus (corresponding to Luteal Phase of Ovary )

The now empty follicle, corpus luteum, starts secreting progesterone that exert a negative feedback on secretion from LH and FSH, preventing new follicles from maturing.

Progesterone converts the endometrium into a secretory tissue full of glycogen and blood vessels, ready to receive a fertilized egg.


Complex Hormonal Control of Two Cycles Ovarian and uterine cycles are controlled by

several hormones, which display complex interactions

Extra-ovarian hormones GnRH from the hypothalamus FSH and LH from the anterior pituitary

Ovarian hormones Estrogen Progesterone Inhibin

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsDAYS

36.4

36.7

7 14 21 28/028/0

Follicular Phase Ovulation Luteal Phase

Phases of theUterine Cycle

Phases of theOvarian Cycle

Basal bodytemperature

(–C)

Uterinecycle

Ovarianhormone

levels

Ovariancycle

Gonadotrophichormone

levels

Primaryfollicle Theca Ovulation

Corpusluteum

formation

Maturecorpusluteum

Corpusalbicans

Progesterone

MENSES PROLIFERATIVEPHASE

SECRETORY PHASE

InhibinEstrogen

Antrum

LH

FSH

Figure 26-13 (4 of 4)

Corpus Luteum Degenerates and Ceases Hormone Production


LHFSH

GnRH

Androgens

Estrogens

(a) Early to mid-follicular phase

Follicle

Granulosacells

Thecalcells

(b) Late follicular phase and ovulation (d) Late luteal phase

FSH LH

New folliclesbegin todevelop

Corpusluteum

dies

Tonic secretionresumes

Corpus luteum

Progesterone

Ovum

LHFSH

Follicle

Estrogen andprogesterone

FSH LH

Corpus luteum(from ovulated

follicle)

EstrogenProgesterone

Inhibin

GnRHGnRH

secretes

(c) Early to mid-luteal phase

Estrogen

Inhibin

Follicle

Granulosacells

Thecalcells

Inhibin

High estrogenoutput

Small amount ofprogesterone

Androgens

LHFSH

GnRH

Pituitary Hypothalamus

Figure 26-14 (4 of 4)

Hormonal Control of the Menstrual Cycle: Late Luteal Phase


Menstrual phase Proliferetive phase

Secretory phase

Follicular/preovulatory phase Luteal/postovulatory phase

Days 1-5 6-14 15-28

Hormones All low High estrogen; low progesterone

High progesterone; low estradiol

Endometrium

Necrotic tissue falls away from the uterine wall

Repaired and become thicker

Very well vascularized. Thick

Glands Not developed. Simple Gland proliferate Glands increase in size and secrete nutritional substances

Follicles Primordial follicles develop into primary and then secondary follicles

One follicle continue to grow into Graafian follicle and ovulate by the end of this phase

No follicular development. Corpus luteum is present

Oocyte/s First meiosis; arrested in prophase I First meiosis completed; secondary oocyte arrested in metaphase II ovulates

If fertilization occur second meiosis is completed


Mammary Glands Pectoral fat pad Modified sweat glands consisting of 15-25 lobes that

radiate around and open at the nipple Areola – pigmented skin surrounding the nipple Lobes contain glandular alveoli that produce milk in

lactating women alveolar glands pass milk to lactiferous ducts, which

open to the outside


Mammary Glands nonlactating breast consists mostly of adipose and

collagenous tissue and contains very little mammary gland.

Lactating develops during pregnancy, it exhibits 15–20 lobes arranged around the nipple,

each drained by a lactiferous duct. These dilate to form a lactiferous sinus opening into the nipple.

Female reproductive syste m

Documents

Transcript of Female reproductive syste m