Week 1 Flashcards
describe the anatomy and function of the hypothalamus?
situated below the thalamus but above the pituitary. with the medulla oblongata caudal function - integrator of neurone + endocrine system - regulates reproduction - the important areas; pre-optic area, media-basal hypothalamus.
what is GnRH?
is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
Prolactin is inhibited when released, regulating negativity.
what is the release pattern of GnRH?
pulsatile -
GnRH binds to receptor on gonadrotope cell in AP, but must be pulsatile to have an intraceuller effect.
how is LH and FSH secretion regulated?
LH release and synthesis under GnRh regulation
FSH synthesis and release constitutive + under control by peptide regulators: Oestradiol!!
describe the hormone feedback from a release of GnRH?
⬆️GnRH = ⬆️LH + ⬇️FSH = oestradiol ovarian peptides ➡️ progesterone androgens causing GnRH surge and less FSH.
describe the general histological arrangement of the ovary?
surface epithelium layer, tunica albuginea, medulla, cortex.
ovary derived from oocyte - arrested in diplotene stage of meiosis, completed a fertilisation.
what are primordial follicles?
folliculogenesis, primordiale pool - mid late gestations
affected by age, breed, nutrition stage.
name the 5 follicles in the ovary?
primary secondary tertiary preovulatory atretic
describe primary follicle?
start, becomes cuboidal surrondnded by interstitial fluid, onset of follicular growth.
describe secondary follicles?
cell proliferation, often termed ‘prenatal’
describe tertiary follicles?
vesicular or ontral
antrum formation as granulosa and theca proliferation .
Gonodropoptin - dependent growth, driven by FSH, strike genesis increasing markers.
describe preovulatory follicles?
very enlarged, protruding on ovarian surface, except at hilus, hormones trigger ovulation
describe atretic follicles?
fast of majority > 99% sudden death of granuloma cells. Apoptotic process.
early Atresia - necrotic granulosa cells
late atresia - more necrotic granulosa cells.
describe the clinical application of follicle function?
manipulation of follicle function, oestrus synchronisation, super ovulation (MOET)
what does luteolysis involve?
PGF2a
Oxytocin.
what are neoplasms?
granulosa cell tumours
what is follicular devoplemnt?
‘ovarian reserve’ and recruitment of primordial follicles.
primordial follicle pools - resting follicles present form birth in females.
devolpment includes: recruitment, follicular grow and ovulation.
what percentage of growing follicles make it to ovulation?
1%
summarise the follicular growth in cows?
takes 3 months (150 days)
almost all follicles move into atresia death
LH ans FSH levels important in final stages of atrial follicle growth and development.
after recruitment - primary and secondary follicles respond to FSH + early ant rail follicles with response to LH.
Antral follicles produce steroid hormones = acerbate growth
what is the main function of progesterone?
synthesed by LH theca cells - converted into androgens
cholesterol uptake by theca cells turns into progestrone.
how is oestradiol produed?
androgens from LH theca cells pass through granulosa cells + converted into oestradiol
armature enzyme used for conversion
what is follicular wave growth?
non-ovulatory species (one offspring)
small astral follicles become complete FSH-dependent.
but the last follicle becomes LH dependent
what does the last follicle become dependent o and what does this cause?
dependent on LH pulse frequency and determines if dominant follicle growth occurs.
why must there be frequent Lh pulses occurring for dominant follicle growth?
frequent pulses = max amount of oestradiol produced for follicle growth + ovulate.
final masturation and ovulation.
what causes ovulation of the DF? (dominant follicle)?
LH pulse frequency increases,
oestradiol synthesis increases rapidly, including GnRH thus LH/FSH surge occurs
causing ovulation of DF.
follicular phase: oestradiol rise, surge and ovulation
what’s the difference between spontaneous ovulations and reduced/induced ovualitors?
spontaneous - rapid rise in oestradiol, with or without onset of lutenization, induces GnRH surge
Induced - a neuroendocrine reflex induces the GnRH
what is cumulus expansion?
cumulus cells withdraw from sticky matrix without spermentaoza, need to pernetrate in order to fertilise egg, the oocyte separate fluid in antrum but surrounded by broncos cells
what is the Corpus Luteum?
develops from the transforming and proliferating follicle wall cells - CL can secret progesterone during luteal phase.
what is the need for progesterone?
negative ffedback on hypothalamus GnRH secretion - suppresses pulse frequency and surge.
what is Luteolysis?
CL regression must occur in absents of pregnancy so female can come onto heat and ovulate again
what is active luteolysis?
PGF2a causes regression of CL. the endodertrium is large animals produce PGF2a
Ruminants : secretion of PGF2a into uterine vein
: direct uptake of PGF2a into ovarian artery
: arterial supply to CL delivers undiluted PGF2a - CL regresses.
what is passive luteolysis?
LH, prolactin decline in circulation, CL no longer supported to produce progesterone and regresses.
Progesterone declines rapidly
(occurs in small animals)
describe the ovary function?
ova devoplment and release
Hormone production and release.
what does the ovary consist of?
Hilus - attachment site for supporting structures
Vascular zone - usually central
Parenchymal zone - peripheral, ova + hormone production, ovulation
how is the mare ovary different?
the regions are reversed, The parenchymal zone in central Vascular zone is peripheral Broad hilus and a central depression
discuss how the ovary is examined?
transrectal palpation (cow and mare) Ultrasound - fluid = anechoic = black soft tissue = echogenic = grey
describe pre-ovulatory follicles in mare?
atretic follicles regress
cow = 1-2cm
mare 3-5cm
Mare = preovulatoty follicle migrates towards ovulation fossa
soft on palpation, pears shaped in ultrasound
explain the luteal phase?
corpus haemorrhgium/rubrim
forms a space made by follicle, not palpable, visible = ultrasound,
describe CL?
Corpus Luteum - occupies space left by follicle, solid structure, echongenus in ultrasound, may contain central fluid (Lacuna),
Produces Progesterone - causes: behavioural changes
; changes to tract.
describe ovarian follicles?
follicles that contain 1 ovum , grow on surface, fluid filled,
Produce Oestrogen - causes: behavioural changes and
Changes to tract. (allows segment travel)
identify the different stages of the oestrus cycle?
oestrus and ovulation HEAT = oestrus (standing to be mounted (mating)) The Luteal Phase (functional lifespan of CL) Rise in progesterone levels Follicular Phase (CL regression, start of LH surge, Oestrus begins again)
what effect does a increased GnRH Surge cause?
during follicular phase, increase in ovarian hormones and a peak in Oestradiol
what effect does a decrease in GnRH surge cause?
Luteal phase, increase in ovarian hormones OR elevated progesterone levels.
what hormone prepare tract for fertilisation?
oestradiol
what hormone prepare tract for pregnancy?
progesterone
define Met-oesturs
Di-oestrus
Pro-oestrus
1 - same as oestrus
2 - same as follicular phase
3 - leads to oestrus
what is the tubular tract?
consists of paramesonphric duct, uterine horns, uterine tubes that fuse caudally - uterine body and vagina cervix
joins at urogenital sinus
function of uterine tubes?
transport sperm proximally + ovum distally
infundibulum - funnel shaped
Ampulla - short proximal section, site of fertilisation
Isthumus - long, narrow, and tubles, opens into uterine horn.
function of Uterus?
litter producing species - very long uterine horns. pig and cow have very long horns and Dog has short, sheep has a coiled horns like a rams horns, long septum uterus
use of intercornual ligaments?
dorsal, ventral and useful for manipulation of tract recally
what are caruncles?
site of membrane faetals - located on endometrium.
concave structure on sheep
describe cervix?
function - sphincter - controls passage between uterus and vagina.
When is the sphincter in the cervix open?
during oestrus + parturition, passage of semen, lubricant mucous
when is the sphincter in cervix closed?
during luteal phase + pregnancy, increased tone and sticky mucous.
describe the structure of vagina and surrounding structures?
vagina - cervix to urthral orifice = long
epithiuelm affected by ovarian hormones, vaginal cytology
Vestibule - urthral orficie to vulva - short
describe the Bitch urethral orifice?
raised above vestibular floor, depression on either side, urinary catheterisation = difficult!!
describe the cow urethral orifice?
suburethral diverticulum, care when passing catheter.
describe the Clitoral fossa?
contains the clitoris, (homologous to penis)
Mare - contagious equine metritis swabs
Bitch - vestibule bulbs, erectile tissue, contribute to ‘tie’ at mating, vestibule glands - mucous production.
describe the vulva?
two skin layers covered by labia,
during oestrus; Bitch - swollen
cow - bulling sring
mare - inversion of clitoris
name the supporting structure of the female reproductive system?
Broad ligament - suspends tract
Mesovarium - supports ovary
Mesometrium - uterus and cdrvix
Mesosalphinx - uterine horn and ovary sac
explain the mesosalphinx?
Fold of tissue, forms ovarian bursa,
Cow/sow - shallow and open
Mare - infunibulm attached at ovulation fossa
Bitch - fat filled, slit like opening, Bursa and ovary BOTH removed in bitch spay
what are the 3 main arteries supplying the ovary?
ovarian artery - direct form aorta, high pressure, ovary, uterine tubes, uterus
uterine artery - low pressure, branch from iliac artery, supplies uterus, forms arterial arcade,
vaginal artery - branch of internal or external iliac artery, supplies coulda tract
explain the venous supply ovaries?
mirrors the arterial supply.
explain the lymphatic drainage and nerve supply for the ovaries?
lymph - ovaries and cranial tract = aortic + medial like node
nerves - innveraiton PS = fibres from pelvic nerves
S = follows partial blood vessels.
describe the oestrus cycle in the cow?
21 days
LH pulsatility changes depending on progesterone concentrations.
during - 2-3 follicles (DF) are selected, each follicle wave emerges following FSH rise + DF selection, LH pulsalitiy determines survival growth + oestradial production from selected DF
Describe the mare oestrus cycle?
21 days
similar to cow rise in FSH, emerging of follicle wave, dominant follicle selection during FSH decline, mid cycle DF selected.
oestrus 5-7 days due to high oestradial.
LH peaks after ovulation,
14 day luteal phase 7 day oestrus phase by PGF2a
describe the graph of the mare oestrus cycle?
oestrus lasts for 7 days, with an oestrdaiol surge causing an LH surge after ovulation - causes rapid lutinisaiton and oestrus ends - Rapid lutinisaiton + increase in production, leading to an adrupt decline in lutrolysis. day 15 oestrus starts again and ovulation occurs 1-2 days before end
Describe the oestrus cycle in ewe?
17 days ovulation at end of cycle 14 day luteal phase 2-4 day follicle wave per cycle multiple ovulation service last two cycles.
describe the graph of the ewe oestrus cycle?
Oestradiol rise at start with oestrus and progesterone/LH levels low.
day 3 LH surge occurs and 14 day luteal phase with a slow increase in progesterone. with a abrupt decline due to PGF2a
levels of oestrdial fluctuate through out the cycle
what regulates seasonality??
The pineal gland - releases melatonin + controls temperature and nutrition.
Pineal gland positioned just above Thalamus.
melatonin is released under hours of darkness. reflects change sin day enter due to light exposure.
how does melatonin onset the breeding season?
melatonin is interpreted by hypothalamus and changes response to GnRH neurones to oestrdaiol.
breeding season onset =less negative feedback of oestrdaiol - GnRH + LH pulses become more frequent
Ewes think days become shorter which triggers 1st ovulation of breeding season due to less sunlight in a shed.
what is puberty defined by?
first ovulation, first oestrus, first pregnancy
depends on sex, species, BW gain, season, group size.
summarise the hormonal + follicular events for puberty?
increase in GnRH/LH pusalilty FSH
transient FSH rise + follicle weaves begin
strong NEGATVIE feedback of oestrdoail on GnRH secretion
as puberty approaches less negative feedback by oestrdaiol, more LH pulses - follicler oestrdiaol production increases.
what neurone is the over-all integrator regulate GnRH release?
Kiss-1 neuron
describe the bitch oestrus cycle?
very long inter-oestrus ineterval - 7 months Monooestrus
Pre-oestrus 7-9 days
Oestrus 7-9 days
metoestrus - 2+ months
anooestrus - 2-5 months
Very long luteal phase - onset of progesterone production form lutierising surge until collided causes the LH surge in bitch.
describe the cat oestrus cycle?
induced ovulater, mating causes endocrine reflex causing GnRH surge (vaginal stimulation)
cats always on heat!
Oestradiol rises regularly during breeding season, progesterone rises when CLs develop,
