Physiology of Reproduction - The Female Reproductive Tract

Layers, broad ligament, ovaries, oviduct, uterus, cervix, vagina, vestibule, and vulva terms and functions

Serosa

single layer of flattened squamous cells that cover the surface

allows the uterus to be slippery

protects and forms adhesions

Muscularis

smooth muscle layers consisting of outer longitudinal and inner circular

necessary for peristaltic contractions

What is the muscularis often referred as?

The myometrium of the uterus

Submucosa

varying thickness, houses blood vessels, nerves and lymphatics, supports the mucosa layer

jelly-like, generates fluid

Mucosa

secretory layer of epithelium

opening to glands

contains caruncles in ruminants

What are the submucosa and mucosa often referred to?

endometrium of the uterus

Broad ligament

suspends female reproductive tract in pelvic cavity

develops in embryo

Broad ligament made up of 3 parts:

1. Mesovarium

2. Mesosalpinx

3. Mesometrium

Mesovarium

suspends ovaries

Mesosalpinx

suspends oviducts

Mesometrium

suspends the uterus and parts posterior to the uterus

The broad ligament supports 3 main vessels:

1. Uterine artery

2. Utero-Ovarian artery

3. Caudal Uterine artery

Uterine Artery

blood supply to uterus

Utero-Ovarian Artery

blood supply to v*gina

with dystocia, artery can be crushed and burst

Main functions of ovaries

1. Gametogenic

2. Endocrine

“ ” attach to the mesovarium at the hilus

ovaries

Gametogenic function

release ova

Endocrine function

produces

• progesterone

• oxytocin

• estrogen

• inhibin

What produces progesterone?

corpus luteum

What produces oxytocin?

corpus luteum

What produces estrogen?

follicles (Graafian)

What is inhibin?

negative feedback secretion

In ovaries, does one sometimes work harder than the other? Which one in cattle?

Yes

Right one due to rumen lessening blood flow to left side

Ovarian morphology types

1. Monotocous

2. Polytocous

Monotocous:

normally give birth to one or two offspring

In cattle and ewes, ovary is shaped like an…

ovoid or almond

In mares, ovary is shaped like a…

Kidney bean

Mares have a distinct portion of ovary to develop follicle called?

Ovulation fossa

Polytocous:

normally give birth to multiple offspring

In sows, b*tches, and queens the ovary is shaped like a…

cluster of grapes (lobulated)

Stages of estrous cycle determines?

predominant ovarian structures that are present

Ovarian morphology terms

1. Tunica albuginea

2. Surface epithelium

3. Cortex

4. Medulla

5. Hilus

Structures of the ovary will undergo…

Constant change

Structures of the ovary include:

1. Primordial follicles

2. Primary follicles

3. Secondary follicles

4. Antral follicles

5. Corpus luteum

6. Corpus albican

What is the primordial follicle?

Oocyte surrounded by a single layer of flattened cells

What are the primary follicles?

Oocyte surrounded by a single layer of cuboidal cells

Follicle either develops further or degenerates

What are the secondary follicles?

Surrounded by two or more layers of cuboidal cells

Follicle still doesn’t have an antrum

Oocyte develops a zona pellucida → important for the attachment of sperm cell

What are the antral follicles?

Contain a cell free area filled with follicular fluid (antrum)

Classified as either Tertiary or Graafian follicles

What is the corpus luteum?

Develops after the follicle ovulates

Termed the ‘Yellow Body’ in cattle

What is the corpus albican?

Pale white structure (scar) from a regressed corpus luteum of a previous estrous cycle

Termed the ‘White Body’

Do the structures on an ovary move while undergoing changes?

No

Antral follicle terms

• Oocyte

• Cumulus oophorus

• Granulosa cells

• Basement membrane

• Theca interna cells

• Theca externa cells

What does an oocyte contain?

more genetic material than necessary

What is a cumulus oophorus?

egg bearing hilock

What is the Graafian follicle?

Made up of theca cell and granulosa cells

What do theca cells produce?

androgens → testosterone and steroid hormones (smaller than protein hormones)

What do granulosa cells produce?

take androgens and enzymatically change them to produce estrogens

develop the corpus luteum after ovulation
serve as the site of progesterone production during the diestrus phase of estrous cycle

What does the Graafian follicle develop from?

antral follicles

“preovulatory follicles”

can be palpated through the rectum of cattle and mares since they protrude from the surface

produce large amounts of estrogen

What is an abnormal type of graafian follicle?

Cystic follicle

What is a cystic follicle?

a graafian follicle that doesn’t ovulate and as a result the animal is always displaying signs of estrus or ‘heat’

GNRH → leads to ovulation to get rid of cystic follicle

Can also pop manually but may lead to adhesions

What is a corpus hemorrhagicum?

ovulated depression filled with blood

forms from ovulated follicle on ovary

more yellow = more progesterone; 10 days after heat

no embryo in uterus = regression of corpus luteum

What is the regression of a corpus luteum called?

Luteolysis

What is a corpus luteum?

replaces the corpus hemorrhagicum

cells within produce progesterone

is palpable in cattle, not in mares

What is the Ovum?

80 - 240 microns in diameter

largest cell in the female body

1N comes from mother and 1N comes from father

2N = fertilized egg

What does the ovum contain?

• Zona pellucida

• Perivitelline space

• Vitelline membrane

What is the zona pellucida?

outer membrane of ovum

sperm will bind to and degrade

What is the perivitelline space?

fluid filled gap

What is the vitelline membrane?

houses site of egg

3 portions of the oviduct:

1. Infundibulum

2. Ampulla

3. Isthmus

What is the infundibulum?

Funnel shaped opening into oviduct, contains a fimbria

What is the fimbria?

lace-like structure which is used to “catch” the ova at ovulation

What is the apmulla?

upper half of the oviduct

contains ciliated and non-ciliated columnar cells

What is the isthmus?

lower portion of the oviduct

thicker muscularis

fertilization takes place at the ampulla/isthmus junction

What are the functions of the glad secretions of the oviduct?

1. Nutrients from the mucosa layer for early embryonic development

2. Media from the mucosa layer for ova transport

How long is the ova in the oviduct?

3-6 days

What would happen if the timeframe for the ova in the oviduct was sped up/slowed down?

Environment would become unsuitable

What does the ciliated columnar cells and muscularis layers ensure?

that the ova stays in the appropriate location

What kind of system does the oviduct have?

closed hydrostatic system

Which direction does sperm go?

Up the oviduct

Which direction does ova go?

down the oviduct

What will a blockage of the oviduct cause?

Infertility in women

Uterus is composed of?

two uterine horns and a uterine body

3 main types of Uteri

1. Duplex

2. Bicornuate

3. Simplex

Who has a duplex uteri?

marsupials and rabbits

Who has a bicornuate uteri?

mare and cow; bitch, queen, and sow

Who has a simplex uteri?

Primates

Uterus is composed of what 2 layers

1. Endometrium

2. Myometrium

Characteristics of the endometrium

Consists of the mucosa and submucosa

lines the lumen

location of the uterine glands

location of the caruncles

What are caruncles?

specific site of placental attachment with fetal cotyledons

ranges in size from 1/4”(not preg) to 3-4”(preg)

combination of caruncle and cotyledon during pregnancy is called?

placentome

“sloughing off” or “bloody discharge” happens when?

2 days after female heat due to the rupture of blood vessels following an elevated estrogen

observed in 50% of cows, however 100% will have discharge

Characteristics of the myometrium

comprised of the inner circular and outer longitudinal muscles

responsible for the uterine contractions which follow genital stimulation

What is the importance of uterine contractions?

aid in sperm transport and expulsion of the fetus

What is oxytocin responsible for?

causes uterine contractions, but works best when combined with estrogen → works together synergistically

4 types of cervices

1. Transverse Folds

2. Spiral Arrangement

3. Longitudinal Folds

4. Single Ring

Transverse fold characteristics

sheep and cattle

Fornix vagina is the cervical/vagina junction

Fornix

junction between cervix and vagina

Spiral arrangement characteristics

sow

no fornix

glans penis in boar is in spiral arrangement and needs pressure for ejaculation

Longitudinal folds characteristics

mare

enlarges during heat or estrus

Single ring characteristics

B*tch

Functions of the cervix

secretes mucus-like secretion from cervical mucosa

Estrogen

thin mucus-like secretion, which allows semen passage and fertilization

Progesterone

thick mucus-like secretion, which creates a cervical seal and prevents entrance of bacteria into the uterus

Characteristics of the v*gina

point where urinary and reproductive tracts join together

copulatory organ of the female

receptacle for semen during natural mating

separated from the vagina by the hymen

Hymen

usually generates by puberty or is penetrated by natural or artificial service

doesn’t break in some filly’s

What is vaginal prolapse?

protrusion of the internal organ, usually in ewes (rare in sows or mares)

can be fixed by sewing, but since it is heritable animals should be culled

Characteristics of the vestibule

spans from the hymen to the vulva

locations of the vestibular glands, which aid in lubrication of the vestibule and vagina for natural mating

Characteristics of the vulva

capable of secretions

contains the clitoris which is homologous to the penis

consists of the left labia and right labia

separated by the anus by the cutaneous bridge