Animal Repro Lab Practical

what’s the difference between estrous and estrus?

• estrous is 21 days long and is the “entire” process

• estrus is 28 days long and is “heat”

HPG axis

• Hypothalamus

• Gonads

• Pituitary

hypothalamus releasing hormone

GnRH

gonad releasing hormone(s)

• ovaries — estrogen, progesteron

• testes — testosterone

pituitary releasing hormone(s)

• LH

• FSH

what hormone caused by what ovarian structure causes (estrogen increase) to happen?

estrogen by the dominant follicles

what hormone is released from where to lead to this occuring increase in estrogen to occur?

surge of GnRH or LH

where does progesterone come from?

ovaries - specifically the corpus luteum and the granulosa cells in dominant follicle

where does estrogen come from?

ovarian follicles — granulosa cells within those

what hormone comes from the hypothalamus?

GnRH

what tissue does GnRH signal to?

the pituitary

what does GnRH cuase the release of?

LH + FSH

what tissue does the released hormone (GnRH) interact with?

gonads

what feedback does GnRH have on the hypothalamus?

positive feedback (depends)

what feedback does progesterone have on the hypothalamus?

negative feedback

what hormone is released by the hypothalamus and responsible for controlling reproduction?

GnRHw

what hormone is released by the pituitary gland and responsible for encouraging follicular growth?

follicle stimulating hormone (FSH)

the ovary tells the rest of the body it has a dominant follicle by releasing what hormone?

estrogen

what structure is on the ovary when the female has ovulated and is waiting to “hear” if they are pregnant?

corpus luteum

the LH surge is largely the result of what hormone reaching a threshold?

estrogen

what signal comes from the uterus to say no embryo has arrived?

PGF2alpha

what specific cell in the ovary is responsible for estrogen production?

granulosa cells

what time does progesterone work on to prevent a dominant follicle and ovulation?

the hypothalamus

how long is the estrous cycle in cattle?

21 days

when the female is in what stage will she be receptive to the male?

estrus

when a dominant follicle is present a surge of what hormone form the hypothalamus starts the ovulatory process?

GnRH

we can use exogenous hormones to remove a functional corpus luteum in a cow? (T/F)

true

ovary function

• site of gametogenesis in the female

• producer of various endocrine signals

the ovary directly attached to the female tract? (T/F)

false

ovary structure

divided into outer cortex and central medulla

medulla of the ovary

composed of mainly connective tissue

blood vessels and nerves enter the ovary at the _____

hilus

cortex of the ovary

• main functional area of the ovary

• performs the gametogenic and endocrine functions

germinal eputhelium

outermost layer of the ovary

tunica albuginea

layer of connective tissue that is immediately beneath the germinal epithelium

• analogous to the connective tissue covering the testis

ovary follicles

• primordial

• primary

• secondary

• tertiary

• antral/dominant follicle

• corpus hemorrhagicum

• corpus luteum

• corpus albicans

primordial follicle

a resting oocyte which is surrounded by flattened follicle cells

primary follicle

oocyte surrounded by a single layer of follicle cells — granulosa cells

• cuboidal in the growing follicle

secondary follicle

oocyte with a zona pellucida and two or more layers of granulosa cells but without an antrumt

teritary follicle

follicle with an antrum often referred to as an antral follicle — eventually it is a tertiary follicle that reaches a size making it competent for ovulation

• a dominant of Graafian follicle

zona pellucida

a thick non-cellular membrane surrounding the oocyte made of 3 glycoproteins — plays a critical role in fertilization

cumulus-granulosa cells

cells directly surrounding the oocyte that are shed with the egg at ovulation — plays a critical role in fertilization and egg transport

follicular fluid

a fluid which is secreted by granulosa cells — this is the fluid that fills the antrum of antral follicles

granulosa cells

these cells multiply rapidly during follicular growth, secrete the follicular fluid, and produce steroids — before ovulation the granulosa cells are the source of estrogen

basement membrane

noncellular layer separating the granulosa and the theca interna — in normal follicles, blood vessels do not cross the basement membrane until the time of ovulation

theca interna

these cells work with the granulosa cells to produce steroids, particularly estrogen, by the follicle

theca externa

outer layer of connective tissue with doubtful endocrine function but probably does plays a role in ovulation

corpus luteum

seen as a very prominent structure on the ovary (following ovulation) and plays an important role in the estrous cycle and pregnancy

• yellow body

• produces progesterone

corpus hemorrhagicum

bloody-appearing structure formed from the freshly ovulated follicle and found from days 1-3 following ovulation

• red body

corpus albicans

white, pale yellow or brown structure that is left when the CL regresses (luteolysis)

• white body

• similar to scar tissue

• does NOT serve a function

uterine tube function

• providing a route for the ovulated oocyte to travel to the uterus

• allows sperm to travel to meet the egg making it the site of fertilization

• supports early embryo development

the anterior end of the Mullerian ducts give rise to the _____ _____

uterine tube

organ of gestation

uterus

uterine tube structure (closest to the ovary — into the uterus)

• infundibulum

• ampulla

• ampullary-isthmic junction

• isthmus

• utero-tubal junction

layer of the the tube (outside — in)

• serosa

• muscularis

• mucosa

serosa components

epithelium and connective tissue

muscularis components

inner circular and outer longitudinal muscle layer

mucosa components

single layer of epithelia cells

infunidibulum

funnel-shaped end of the uterine tube

• end of the funnel = finger like projections called fimbrae

• at ovulation the ciliated surface of the fimbria and infundibulum “catch” the ovulated egg and transport it to the base of the infundibulum through the ostium and into the ampulla

ampulla

½ of the length of the uterine tube

• mucosa and highly convoluted and well developed

• muscularis is thin

• diameter is larger than isthmus

ampullary-isthmic junction

midway between the ovary and uterus

• site of where fertilization occurs

isthmus

part between the ampulla and uterotubal junction

• muscularis is well-developed which gives the isthmus a hard feel

uterotubal junction

transition between the uterus and the uterine tube

duplex uterus

• 2 separate uterine horns and 2 cervical openings

• rodents and rabbits

simplex uterus

• no uterine horns

• primates

bicornuate uterus

• normal uterus

• farm animals

layers of the uterus

• perimetrium

• myometirum

• endometirum

perimetrium

outermost layer that is continuous with the broad ligament and functions in support

myometrium

thicker inner circular layer and thinner outer longitudinal layer

• functions in all aspects of reproduction from sperm transport and parturition

endometrium

innermost layer of the uterus with simple tubular glands which give uterus the conductive ability to develop an embryo

• in ruminants there are caruncles that serve as the attachment site for cotyledons of the embryo and are the main areas of exchange between mother and fetus

uterus function

provides a sustainable environment for embryos throughout pregnancy and supports sperm viability during the estrus stage of the estrous cycle

in absence of pregnancy the uterus through _______ _____ causes regression of the CL

luteolytic function

cervix

thick-walled sphincter like structure that separates the external environment from the internal environment of the uterus

• has several opposing ridges known as annular rings or folds

cervix function

role in sperm transport, maintenance of pregnancy and parturition

vagina

connects the cervix to the external genitalia

• penis is inserted and the semen is then deposited at the anterior end of the vagina or in the cervix

vagina function

mating process

broad ligament

suspended by ligaments from the dorsal lateral body

broad ligaments subdivisions

• mesosalpinx

• mesovarium

• mesometrium

mesosalpinx

mesentery of the uterine tube

mesovarium

suspensory ligament of the ovary

mesometrium

suspensory ligament of the uterus

what is the correct location for depositing sperm during artificial insemination?

uterine body

what is the earliest time point presented in lab that one can confidently palpate to detect pregnancy?

45 days

the maternal vasculature in the endometrial layer of cows is concentrated in what strucutres?

caruncles

how many CL would you expect to find on the ovaries of a pregnant cow?

1

in cattle when performing AI the ideal location to deposit semen is just outside the external os? (T/F)

false

the isthmus region of the uterine tube has a wider diameter than the ampulla region? (T/F)

false

when palpating a cow or heifer the densest tissue one would feel would be what structure?

cervix

what hormone is crucial for maintaining a pregnancy?

progesterone

what is a breeding soundness exam?

prognostication of a bulls ability to get a cow pregnancy and is typically performed on bulls that are used for natural service

4 major BSE exmaination categories

1.) overall physical exam

• hocks

• eyes

• overall wellness

2.) examination of the reproductive genitalia

• inside accessory sex glands

  • urethralis muscle (wrist deep)

  • prostate

  • vesicular glands (fork #1)

  • ampulla (fork #2)

3.) semen evaluation

4.) scrotal circumfrence

what does scrotal circumference determines what?

total # of sperm

BSE is typically performed under 3 situaitions

1.) pre-purchase sale

2.) pre-breeding season exam — 30 to 60 days prior to start of breeding season

3.) post-breeding season exam — owner suspects fertility problems

physical exam (BSE)

• eyes are clear of any lesions

• oral examination

• general health should be good

body condition (BSE)

• excessively fat bulls lack vigor and the excess fat may negatively affect sperm production

• excessively thin bulls may not have the stamina to service cows during the breeding season

• therefore, bulls must carry some extra weight at the start of the breeding season

conformation and body structure (BSE)

• rear leg confirmation is very important

  • rear legs are load bearing during mounting and copulation

  • necessary for proper mobility around the breeding pasture

• hooves are in good shape and don’t need trimming

• remember that structural faults are heritable

genital exam

• prepuce

• penis

• scrotum

• testis & epididymis

• accessory sex glands

• measuring & importance of scrotal circumference (SC)

prepuce

should be palpated for adhesions, inflammation, and abscesses

preputial problems lead to:

• phimosis

  paraphimosis

phimosis

inability to extend penis through the prepuce