Repro TEST 2

Parts of Female Reproductive Tract

• Ovaries

• Oviducts

• Uterus

• Cervix

• Vagina

• External genetalia

Where is the female reproductive tract located?

Directly beneath the rectum

What does the location of the female reproductive tract allow?

Transrectal palpation and ultrasound (in cows, mares, and camels)

The female reproductive tract could be considered:

A series of interconnected tubes

Serosa

Outermost, single layer of squamous cells

What are the four distinct concentric layers that form the walls of the tubular organs in the female reproductive tract?

• Serosa

• Muscularis

• Submucosa

• Mucosa

Muscularis

Double layer of smooth muscle

Submucosa

Houses blood vessels, nerves, and lymphatics

Mucosa

Secretory layer of epithelium

Broad ligament

Double-layered connective tissue that susends te ovaries, oviducts, uterus, cervix, and anterior vagina. It also houses vasculature (blood vessels), nerves, and lymphatic vessels.

• Develops from the peritoneum (embryonic origin)

Components of the broad ligament

• Mesovarium

• Mesosalpinx

• Mesometrium

Mesovarium

Supports ovary

What are characteristics of the mesovarium?

Houses vessels that form hilus

Mesosalpinx

Supports oviduct

What are characteristics of the mesovarium?

Thin, serous portion that also serves as bursa-like pouch.

Mesometrium

Supports uterine horns

What are characteristics of the mesometrium?

Largest and most conspicuous portion

Characteristics of the ovary

• Undergoes dramatic and predictable remodeling (ovarian cycle)

• Structures on the ovary control the reproductive cycle, behavior, and secretion of other hormones (ex. follicle)

Primary functions of ovary

• Produce oocytes (egg cells)

• Produce hormones

Layers of the ovary

• Germinal epithelium

• Tunica albuginea

• Ovarian cortex

• Ovarian medulla

Germinal epithelium

Not related to germinal cells, single layer of cuboidal cells

Tunica albuginea

Outer connective tissue (of ovary)

Ovarian cortex

Usually houses oocytes & related structures

Ovarian medulla

Central part of ovary, contains vasculature, nerves, and lymphatics.

T/F, ovulation can occur on any point of the cow, ewe, and sow ovary

True, the cortex layer is outside

Why can ovulation not occur on an part of a mare’s ovary?

The mare has an inversion of the cortex and medulla (outside layer) making ovulation only able to occur at the ovulation fossa.

Ovarian structures

• Follicle

• Corpus Luteum

• Corpus hemorrhagicum

• Corpus albicans

Follicle

• contains oocyte

• primary hormone: estradiol

• fluid-filled

• ovulates

• many classifications

Corpus Luteum (CL)

Primary hormone: progesterone

4 types of follicle classifications

• Primordial

• Primary

• Secondary

• Tertiary

Primordial follicles

Most immature (microscropic), single layer of squamous cells

Primary follicles

(microscopic) single layer of cuboidal cells

Secondary follicles

(microscopic) two or more layers of cells

Tertiary follicles

(also called an antral follicle), preovulatory (final, mature follicle just before it releases an egg) = graafian follicle

Tertiary follicle components

• Theca externa

• Theca interna

• Granulosa

Theca externa

Primarily loose connective tissue

Theca interna

Hormone production

Granulosa

Hormone production and oocyte maturation

Parts of Oviduct

• Infundibulum

• Ostium

• Ampulla

• Ampullary-isthmic junction

• Isthmus

• Uterotubal junction

Infundibulum

Funnel-shaped opening to oviduct, “catcher’s mitt”

Ostium

Opening of the oviduct

Ampulla

Half or more of the oviduct, large diameter, many fern-like mucosal folds w/ ciliated epithelium. Wider part of the oviduct where fertilization occurs

Isthmus

Smaller diameter, thick muscular wall and fewer mucosal folds

Uterus

Organ of pregnancy, usually two uterine horns (cornua)

Duplex

2 cervical canals seperating each horn into distinct compartments with one or two vaginal canals

Bicornuate

2 uterine horns and small uterine body

Simplex

Single uterine body with little to no uterine horn

Layers of Uterus

• Perimetrium

• Myometrium

• Endometrium

Perimetrium

Thin serosal layer

Myometrium

Muscularis

Endometrium

Mucosa and submucosa

Caruncles

Cow and ewe - small, button-like bump on the inside lining of the uterus

Endometrial folds

Sow and mare - temporary or permanent ridges of the inner uterine lining

Cervix characteristics

• Barrier to sperm transport (ewe and cow)

• Barrier to external environment during pregnancy

• Produces mucous during estrus (primarily cow and ewe)

Parts of Vagina

• Cranial vagina

• Caudal vagina

Vagina characteristics

• Copulatory (reproductive) organ

• Birth canal

• Site of urine expulsion

Cranial vagina

Generally columnar epithelium, highly secretory, with fornix

Caudal vagina

Stratified squamous epithelium which serves protective functions

Fornix Vagina

Cranial portion of vagina

Characteristic of fornix vagina

Protrusion of cervix into vagina

3 external genetalia

1. Vulva

2. Clitoris

3. Perineum

Vulva

External portion of female tract

Characteristics of vulva

• 2 labia (major & minor) - mostly adipose (fat) tissue with small bundles of smooth muscle

• Meet to form 2 commissures (dorsal and ventral)

Clitoris

Female homologue (counterpart) of penis, housed in ventral commissure

Perineum

Region surrounding anus and vulva

Reproductive Cyclicity

• Estrous Cycle

• Menstrual Cycle

Estrous cycle

Series of predictable reproductive events that begin at estrus and continue until the subsequent estrus

Estrus (heat)

NOUN: Period when a female is receptive to copulation (breeding) with the male. ex: “The cow is displaying ___”

Estrous

ADJ : “The length of the _____ cycle in the pig is 21 days”

Anestrus

Without cyclcity; ovaries are (relatively) inactive. Neither ovulatory follicles or corpora lutea are present.

Types of estrous cycles

• Polyestrus

• Seasonally Polyestrus

• Monoestrus

Polyestrus

Uniform distribution of estrous cycles throughout the year

Seasonally Polyestrus

“Clusters” of estrous cycles that occur during a certain season of the year

Monoestrus

Only one cycle per year

Folliculogenesis

Some primordial follicles vegin to grow continuously throughout life

• The number that develops to maturity depends on species, breed, environmental factors, etc.

(Folliculogenesis) control mechanism unknown, two fates…

1. Ovulation

2. Atresia (follicle breaks down and dies before maturity)

Breed specific follicle maturation count

Swine = 10-25

Sheep = 1-3

Cattle, Horses, Humans = 1

Follicular wave steps

1. Initially, a group of follicles (recruitment)

2. Some will develop, while others will die (atresia)

3. A dominant follicle is selected for continued growth to preovulatory size (selection)

4. If the follicle achieves dominance around the time of luteolysis (breakdown of the corpus luteum), the follicle will ovulate. (dominance)

T/F Follicles make estradiol

True

Steroidogenic Acute Regulatory Protein (StAR protein)

Transport protein that transfers cholesterol into the inner mitochondrial membrane

• This is the rate limiting step for steroidogenesis

Two types of ovulators

1. Induced (reflex)

2. Spontaneous

Induced (reflex) ovulators

Rabbit, cat, ferret, and mink. Intromission stimulates the surge of LH ovulation. Ovulation occurs through the neuroendocrine reflex

Spontaneous ovulators

Farm animals and humans. Controlled by events of estrous or menstrual cycle and not affected by intromission (insertion).

How does spontanuous ovulation occur?

• Due to endogenous endocrine and neuroendocrine factors

• Copulation or presence of male is not necessary for ovulation to occur

Effect of estradiol on vagina

(ESPECIALLY caudal) mucosa increases in thickness

Effect of estradiol on cervix and cranial vagina

Produces mucous for..

• Lubrication

• Flush foreign material following copulation

• Sperm transport

Effect of estradiol on uterus

Development of uterine glands

Effect of estradiol on oviduct

increases secretory rate; cilia increase beat frequency

General actions of estradiol

Increased blood flow (hyperemia) to all of reproductive tract

• facilitates secretion

• Delivery of leukocytes to submucosa

• Edema of external genetailia

• Delivery of hormones and metabolites

Effect of estradiol on muscularis

Increased tone and motility of muscularis in all regions of tract

Elevated estradiol and low progesterone

Reproductive behavior

Effect of estradiol on hypothalamus

GnRH (Gonadotropin releasing hormone) surge leading to LH surge leading to ovulation

Deterministic model for ovulation

Increased GnRH secretion is required to induce the preovulatory LH surge and thus ovulation

Permissive model for ovulation

GnRH secretion need not increase. Rather, the preovulatory LH surge results from enhanced sensitivity of the pituitary gland to GnRH.

Process of ovulation

1. Hyperemia of the ovary (7X increase in blood flow)

2. Theca interna becomes edematous (swollen), resulting in increased hydrostatic pressure

3. Theca interna begins to produce progesterone instead of androstenedione

4. Progesterone stimulates synthesis of collagenase

5. Follicular fluid volume increases

6. Basement membrane disintegrates

7. Stigma of follicle outward and weaken

Process of Ovulation (PGF_2a )

Synthesized and secreted by the ovary which

1. causes lysossomes in granulosa to rupture

2. causes contractions of smooth muscle of ovary

Process of Ovulation (PGE₂ )

Activates plasminogen (converted to plasmin)

• Together assist with remodeling follicle into corpus luteum

PGE₂

Synthesized and secreted by ovary

Formation of CL

1. Luteinization

2. Walls of follicle collapse forming folds that allow mixing of cells (happens after ovulation)

3. Granulosa become large luteal cells

4. Theca become small luteal cells

Large luteal cells

• 20-70 micrometers (µm)

• Majority of progesterone synthesis and secretion

• Rarely multiply after ovulation

• Increase in volume (hypertrophy)

• Contain LH receptors, but binding of LH to its receptor does not increase progesterone production in these cells.