ANS 150 Animal Reproduction

What are the characteristics of the ovary?

-Contains thousands of growing follicles

-Receives a rich supply of blood vessels and nerves

What do follicles contain

An ovum or “egg”

Which hormones cause follicles to grow?

Gonadotropins

What do follicles do?

Either die(become atretic) or ovulate and release the egg/ovum

What does the Corpus Luteum do?

Produces a number of hormones associated with pregnancy, primarily progesterone

Where does the Corpus Luteum form?

The tissue that remains after a follicle ovulates.

What is the Corpus Albicans

-Scar tissue left after the corpus luteum dies or regresses.

-Has no function

What occurs in the oviduct?

-Fertilization and early embryonic development

-The transfer of eggs from the ovary to the uterus

What does the uterus do?

-Responsible for the maintenance of the pregnancy by nurturing the fetus

-Releases the hormone that regresses luteral tissue

What does the cervix do?

-Isolates the uterus from the external environment during pregnancy

-Site of semen deposition in some animals

What does the vagina do?

-Protects the uterus from bacterial invasion

-Site of semen deposition in most animals

What two female organs can be the site of semen deposition?

The cervix in some and the vagina in most

What is the vulva?

-External female genitalia

-Involved with recognition of receptivity and in the production of female pheromones

What do the testicles do?

-Produces sperm at every point of tubules

-Produces hormones(testosterone and androgen)

What happens to sperm in the epididymis?

-When sperm passes through the epididymis it becomes fertilized

-Sperm is also stored

What does the vas deferens do?

Serves as a passage for sperm from the epididymis to the urethra during ejaculation

What do the secondary sex glands do?

-Produce and secrete most of the liquid portion of sperm

What are the secondary sex glands?

-Seminal Vesticles (produces most fluid)

-Prostate Glands

-Bulbourethral Glands

What is the Urethra?

The common exit for the male reproductive and urinary systems

Characteristics of the penis?

-Male reproductive organ

-Specialized by animal to deposit semen in a female reproductive tract

What does the sheath do?

-Specialized pouch where the penis remains when not in use

-In some animals, the lining is involved in pheromone production

What is the order of semen production

-Testicle

-Epididymis

-Vas deferens

-Bladder

-Urethra (Secondary sex glands: Seminal vesicles, prostrate gland, bulbourethral glands)

-Penis

What occurs to semen during each step of production?

-In a “suspension” (sperm cells in seminal fluids

-Sperm leaves epididymis (very concentrated)

-Travels through vas deferens to urethra

-Secondary sex glands secrete fluids into urethra that mix with sperm

What are two Gonadotropins:

-Luteinizing hormone (LH)

-Follicle Stimulating hormone (FSH)

What does Follicle Stimulating hormone (FSH) do?

-Stimulates all stages of follicle growth especially during early periods

What does Luteinizing hormone (LH) do?

-Stimulates the final growth of follicles

-Causes Ovulation

-Stimulates the Corpus Luteum

What are two organs that produce progesterone?

-Corpus Luteum

-Placenta(some animals)

What are the sex steroids/prostaglandins

-Progesterone

-Estrogen

-Prostaglandin F2 alpha

What does progesterone do?

-Inhibits gonadotropin secretion

-Responsible for the maintenance of pregnancy

What does Estrogen do?

-Stimulates pre-ovulatory surge of gonadotropins

-Prepares female for breeding and parturition

-Responsible for female mating behaviors

What is Estrogen produced by?

Growing follicles, placenta, and embryos

What does Prostaglandin F2 alpha do?

-Causes uterine contractions at birth

-Responsible for luteal regression

Where is Prostaglandin F2 alpha primarily produced?

In the uterus

What are the Mammotropins?

-Prolactin

-Oxytocin

What does prolactin do?

Stimulates the production of milk

Which organ produces prolactin

The pituitary gland

What does Oxytocin do?

-Stimulates milk excretion

-Stimulates uterine contractions

Where is Oxytocin produced?

The uterus and hypothalamus

Puberty definition

The age an animal is capable of adult reproductive function

What are the female signs of puberty?

-Showing estrus

-Production of fertile eggs

-Maintenance of pregnancy

What are the male signs of puberty

-Libido

-Mating

-Production of fertile sperm

What are the last functions to mature during puberty

-The brain

-Luteinizing hormone (LH)

What can occur before puberty?

Ovaries and testes are capable of gamete and hormone production

What are the estrous cycles?

Repeatable sequence of events that results in the female becoming sexually receptive

Estrous Cycles Order(Gonna come back to)

About how long does it take for a female body to recognize its pregnancy

About 12 days after fertilization

What happens when the body knows it’s pregnant

-Embryo sends signal to mother

-Prostaglandins are not released from the uterus

-Progesterone is maintained

-Embryo begins to differentiate

What happens in the blastocyst?

-Inner cell mass becomes fetus proper

-Cells within inner cell mass differentiate into bones, muscles, nerves, etc.

-Trophoblast becomes placental membranes of fetus

When is an embryo referred to as a fetus?

After it begins to differentiate and begins to take the shape and form of a young animal

What rate does the fetus size increase?

A steady rate

What rate does the fetus weight increase?

-Weight increases slowly the first 2/3 of pregnancy

-Most weight gain is seen in the last 1/3 of pregnancy

What occurs during parturition?

-Prostaglandins are released

-Progesterone decreases (increases then decreases in horses)

-Endocrine changes vary among species after this point

What is ferguson’s reflex(neural reflex arc)

- Stimulation of the pressure receptors by the fetus pushing against them stimulates oxytocin release

-Oxytocin stimulates contraction to push fetus through birth canal

What is parturition initiated by?

The fetus

What causes lactation?

The physical stimulation of the nipple during nursing releases prolactin and oxytocin

What happens the more an animal nurses?

The more milk the mother produces

What does suckling do?

Prevents the release of LH and FSH

What happens when suckling ends?

LH and FSH increase and estrus starts

What do LH and FSH do in males

-Stimulate sperm production (spermatogenesis)

-Stimulate testosterone production (mostly LH)

How long does it take a new wave of sperm cells to develop

3 days

What happens to sperm cells in the developing pool (testicle and epididymis)

-They divide to form many new sperm cells

-Earn the ability to fertilize eggs

How long does sperm production take

5-7 weeks