Exam 3: Female Reproduction

Estrous

The reproductive cycle in females that are an estrual species

Estrual species’

bovine, ovine, porcine, caprine, canine, and feline

Estrus of Heat

The period of time in which a female is sexually receptive to the male for the purposes of mating

Anestrous Period

The time when a female is not in estrus

• the non-breeding season

Estrous Synchronization

Controlling the estrous cycle so that a high percentage of the females in the herd express estrus (receptivity) at the same time

Clone

An individual grown from a single somatic cell of its parent and genetically identical to it

A.I.

Abbreviation for artificial insemination, a common technique used in reproductive biology that involves placing semen into the reproductive tract of the female by artificial techniques rather than natural mating

E.T.

Abbreviation for embryo transfer, which is a procedure used to transfer embryos from a donor female to a group of recipient females

Haploid

Half the normal number of chromosomes.

• found in sperm and ova

Open

refers to non-pregnant females

Fertility

The capacity to initiate, sustain, and support reproduction

Dystocia

Difficult birth

• Intervention required

Vulva/ Vagina

Female organ for copulation; birth canal for parturition

Cervix

Passage way for sperm following breeding; seals off the uterus during pregnancy

Uterus

Secretory organ; incubator for embryo and placenta; control of cyclicity (leuteolysis which destroys the corpus luteum); contraction for parturition

Oviduct

passage for ovum and sperm, site of fertilization

Ovary

produces female gamete and female sex hormones (estrogen and progesterone)

Vulva

• passageway for urine

• receptor for the penis during copulation

• expands at parturition for the delivery of the fetus

• Not to be confused with the anus!

Vagina and cervix

• Tissue is keratinized to protect against abrasion

• Secretory

• Provides barriers (main function of the cervix)

What is the site of semen deposition?

Fornix vagina (cow/ewe)

Does the vagina have glands?

No

Where do vaginal secretions come from?

Secretions come from the passage of plasma components as well as the cervix

What part of the reproductive system provided lubrication?

vagina

What is the pH of the vagina?

pH is acidic (5.7)- bacteriostatic

How does the vagina function as a birth canal?

Dilates for the fetus during parturition

What is the function composed on?

Composed of cartilage surrounded by soft tissue

Openings of the cervix:

Openings are the external of internal Os

What is the cervix a passageway for?

• Passageway for sperm following breeding

• Passageway for fetus

What does the cervix secrete?

Secretes mucous, seals off uterus during pregnancy

Do all animals have the same cervix?

No, different species have different configurations (rings, spirals, or folds)

Components of a Cow cervix:

• The cervix is very hard and rigid during estrus

• composed of thick connective tissue

• longitudinal folds

Components of a Mare cervix:

• Longitudinal folds

• There are no obstacles in the mare after the fornix vagina

• Opposite of other species, as the cervix is soft and pliable during estrus

Characteristics of the Sow cervix:

“Cork screw”

• Sow cervix has many interdigitating pads

• Sow does NOT have fornix vagina

What is another word for uterus

Womb

Functions of the uterus

• incubator for a fertilized ovum, nutrients for the ovum

• aids the travel of sperm

• secretory organ (hormones and mucus)

Look of the uterus

Has two horns or branches and a single body

• shape differs between species

Advanced Duplex uterus species

opossum

Duplex uterus species

Rabbit, mouse

Bicornuate cervix species

Pig

Bipartite uterus species

cow, ewe, and doe

Modified bipartite uterus species

mare

Simplex uterus species

Human

6 functions of the uterus

1. transport sperm

2. muscle contractions

3. sperm motility

4. absorption and phagocytosis

5. partially prepares sperm for fertilization

6. provides an environment for the embryo

7. supports the development of the fetus

8. At birth, it expels the fetus

9. recovers from pregnancy

functions of the uterus: transport sperm

estrogen stimulates myometrial contractions so that sperm can move to site of fertilization

functions of the uterus: muscle contractions

towards the oviduct during estrus (heat), but following ovulation, they are toward the cervix until progesterone increases from CL

functions of the uterus: Sperm motility

Viable sperm (motile) are important so that they are not absorbed

functions of the uterus: absorption and phagocytosis

Occurs by uterine epithelium and leukocytes, which fight infection

functions of the uterus: partially prepares sperm for fertilization

• Estrogen stimulates uterine secretions which capacitate sperm (zona pelucida)

functions of the uterus: provides environment for the embryo

• uterine secretions stimulated by estrogen and progesterone

• proper timing of embryo and uterus is important for embryo transfer

functions of the uterus: supports development of the fetus

• Quiescent myometrium- progesterone

• immunological protection from rejection by the maternal immune system

functions of the uterus: at birth expels fetus

• strong rhythmic myometrial contractions (progesterone low)

functions of the uterus: recovers from pregnancy

Uterine involution- myometrial contractions and enzymatic activity shrink the uterus back to normal size

If the female is not pregnant, what happens to the CL

Uterine endometrium releases Prostaglandin (PGF2) to cause the CL to regress

If the female is pregnant, what happens to the CL?

Embryo provides a chemical signal (interferon tau) that allows the CL to be maintained

Oviduct

Tube that connects the ovary to the uterus

What are the 3 distinct regions of the oviduct?

1. Infundibulum

2. Ampulla

3. Isthmus

Infundibulum

Surrounds the ovary

Ampulla

• Transport oocyte

Isthmus

• Transport sperm

Significance of the Ampulla-Isthmus junction

It is the site of fertilization

What are the two main regions of the ovary?

Cortex and medulla

Cortex

• outer on all except mare

• produce the female gamete (ovum or oocyte)

  • released from the follicle

• includes ovarian structures

  • Produce hormones

Medulla

• inner on all- except mare

• support tissue including blood vessels and immune cells

How many ovaries do farm animals have?

2

What surrounds the ovary?

Surrounded by connective tissue called the tunica albuginea

What does the ovary produce?

• Produces female gamete (the ovum)- largest single cell in the body

• Produces female sex hormones (estrogen and progesterone)

Follicle structure

Blister-like structure on ovary that contains ovum and hormone rich fluid

3 types of follicles

1. Graafian- mature follicle

2. Atrophic- deteriorated follicle

3. Cystic- continuous Corpus Luteum or Graafian or Atretic structure (uncontrolled growth, failed ovulation)

Corpus Luteum

solid tissue which is composed of luteal cells that originate from granulosa and theca cells of the Graafian follicle

Corpus Luteum functions

Produce progesterone to:

• inhibit estrus and parturition

• block myometrial contractions

• stimulate endometrial secretion of nutrients

• stimulate the production of luteolytic agent to kill the CL if no embryo is present

  • Prostaglandin (PGF2a)

Mare ovary

Single ovulation from the interior cortex is funneled to the oviduct via a specialized structure called the ovulation fossa

Sow Ovary

Multiple ovulations from the cortex located on the exterior or surface of the ovary

• “popcorn”

Follicle development summary

Follicles develop on the ovary and undergo stages of maturation until one becomes a Graafian follicle

What happens to follicles not selected for ovulation?

Follicles not selected for ovulation become atritic and regress

Where will the follicles transition through following ovulation?

Following ovulation (when the oocyte is released from the follicle), the follicles will transition through the CH, CL, and CA structures