Reproductive physiology Flashcards
phases of the estrus cycle
proestrus
estrus
metestrus
diestrus
anestrus
what phases happen during the follicular period(phase)
proestrus and estrus
oocyte matures and ovulation occurs
what phases happen during the luteal period(phase)
metestrus and diestrus
the period from ovulation to degeneration of the corpus luteum
the estrus cycle is regulated by?
hypothalamo-hypophysial-ovarian rhythm
and by environmental factors
Hypothalamus secrets gonadotropin releasing hormone (GnRH) which is
regulating secretion of what from where?
Hypothalamus secrets gonadotropinreleasing hormone (GnRH) which
regulates secretion of FSH and LH from the anterior pituitary
what regulates secretion of FSH and LH from
pituitary
Hypothalamus secretes gonadotropin releasing hormone (GnRH) which in turn regulates secretion of FSH and LH
where does estradiol come from?
secreted by growing follicles
What does high estradiol stimulate?
The higher the estradiol level the more GnRH is
secreted (positive feedback)
what triggers luteolysis?
in the event of no pregnancy, cyclical regression of the corpus luteum is caused by the secretion of prostaglandin F2alpha from the endometrium
what effect does progesterone have on GnRH
Progesterone minimises GnRH production
from hypothalamus.
define capacitation
Capacitation refers to the physiological changes, and motility pattern changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg.
define acrosome reaction
occurs after sperm capacitation, a process that enables the contents of the acrosome to be exposed to the outer membrane of sperm in order to initiate fertilization.
define acrosome
is a cap-like structure over the anterior half of the sperm’s head that contains degradative enzymes that break down the outer membrane of the ovum
morula definition
the morula stage is usually defined as the stage in which the undifferentiated embryo consists of 16-32 cells.
blastocyst definition
By Day 5ish, the embryo, now called a blastocyst, is about 70-100 cells, 2 distinct cellular populatiosn and has a fluid filled lumen in the center.
define zona pellucida
the thick transparent membrane, composed of glycoproteins, surrounding a mammalian ovum before implantation.
maternal recognition of pregnancy in cows and ewes?
embryo produces proteins that prevent
luteolysis
maternal recognition of pregnancy in sows?
embryo produces estradiol that signals existance of
pregnancy to female’s body, and stimulates myometric
contractions to support even distribution of embryos in
uterus
maternal recognition of pregnancy in mare?
presence of embryo prevents luteolysis
define placentation
development of extraembryonic membranes
name the 3 fetal membranes
the amnion,
allantois,
and chorion
yolk sac found in mammals, but it is not nutritive
innermost fetal membrane
the amnion or amniotic sac
middle fetal membrane
allantois
fuses with chorion and amnion
outermost fetal membrane
chorion
which fetal membrane produces hormones
chorion
what sort of substances can diffuse through the placenta?
nutrients (monosaccharides, amino acids, vitamins etc.),
most maternal hormones (except adrenaline),
oxygen,
antibodies,
almost all drugs (including alcohol),
lead (Pb) and DDT
the placenta will secrete what hormones?
horse choriongonadotropin - eCG
FSH
lactogen,
progesterone,
estrogen,
ACTH etc.
how are placenta classified?
according to the configuration of the maternal-fetal interface
name 4 types of placenta in english
diffuse
cotyledonary
zonary
discoid
describe a diffuse placenta
it is almost entirely in contact with the endometrium
almost entire surface of allantochorion is covered by villi (eq)
or a network of short folds (su)
describe a cotyledonary placenta
multiple, discrete areas of attachment called cotyledons are formed by interaction of patches of allantochorion with endometrium.
e.g. ru
describe a zonary placenta
the chorionic villi form a complete or incomplete band of tissue surrounding the fetus
ca, fe, seals, bears, elephants
describe a discoid placenta
an area of the chorion is discoid in shape, adheres to the endometrial stroma
ppl, primates, rodents, rabb
the umbilical cord contains?
commonly two arteries
one (or two) veins
urachus
all embedded in a loose connective tissue – Wharton’s jelly. This is all covered by a thick stratified sheet of embryonic connective tissue
define Teratogen
are substances that may produce physical or functional defects in the embryo or fetus after exposure to substance
define Uterine involution
the process by which the uterus returns to its nonpregnant size
Gonadotropin releasing hormone (GnRH) function
Stimulates release of FSH & LH
Follicle stimulating hormone, FSH - stimulates
growth of ovarian follicles in females and spermatogenesis in males
= gametogenesis in both
Luteinizing hormone, LH - stimulates
secretion of estradiol and progesterone so ovulation and corpus luteum development in females
secretion of testosterone in males
what is inhibin
gonadal peptide hormone that inhibits secretion of FSH
what is the SRY gene
a gene located on the Y chromosome that codes for a protein called testis-determining factor
thus genetic females lack this
define estrus
the period during which a female is receptive to mating
define proestrus
the period preceding estrus during which a female exhibits changes in behavior indicating the approach of estrus
what marks the starting point of an estrus cycle?
the day of ovulation typically, however this is not easily determined, therefore the onset of estrus is used as reference point
describe anestrus
the period when a female does not exhibit reproductive activity
hormonal activity happening during estrus?
estradiol concentration peaks and declines rapidly after ovulation
hormonal activity happening during metestrus?
a corpus luteum is formed and secretion of progesterone commences
hormonal activity happening during diestrus?
a fully functional corpus luteum maintains a high concentration of progesterone in plasma
hormonal activity happening during proestrus?
increasing amounts of estradiol are secreted by growing follicles
define atresia
a form of hormonally controlled apoptosis or ovarian follicle degeneration
where does the zona pellucida come from?
prodcued by follicular granulosa cells that secrete a non-cellula rmembrane that forms the zona pellucida
what type of cell surrounds a developing ovarian follicle?
theca cells
what separates theca and granulosa cells?
a basal lamina
spermatozoa heads release what enzyme so as to be able to penetrate an oocyte’s granulosa cell layer
hyaluronidase
define trophoblast
the cells of the outer layer of a blastocyst that later become the inner 2 fetal membranes
placenta in which both fetal and maternal sides have intact epithelia and separate capillaries is termed?
epitheliochorial placenta type
horses, pigs, ruminants
placenta in which maternal capillaries are in direct contact with chorionic epithelium is termed?
endotheliochorial placenta
dogs and cats
chorionic villi with intact endothelia are in direct contact with maternal blood
hemochorial placenta
primates, rodents
define puerperium
the period of uterine involution + to regaining reproductive function
define lochia
the normal discharge from the uterus after parturition
What are Wolffien ducts
are paired embryonic structures that serve as progenitors of the male internal genitalia
What are Mullerian ducts
are paired embryonic structures that develops into the female reproductive tract
define extraembryonic membranes
includes placenta, allantois, amnion, and chorion.
Allantois function
acts as a reservoir for excretory secretions from the embryo
as well as to exchange gases used by the embryo.
Trophoblast layer and mesoderm layers later unite to become the?
chorion
bovine embryonic implantation takes place at what point?
roughly week 5 after conception
define synepitheliochorial placental interface
some sources report the epitheliochorial placenta in cows and sheep to truly contain one more layer thus this second term can be used
what placenta does not convey passive immunity to offspring and what species does this type relate to
epitheliochorial placenta does not convey Ig’s and thus colostrum is essential
cows, sow, mare
what placenta does not convey passive immunity to offspring via blood and what species does this type relate to
epitheliochorial placenta does not convey Ig’s and thus colostrum is essential
cows, sow, mare
Relaxin function and where it produced?
softens connective tissues,
enables uterus to enlarge,
widens the pelvis,
concentration increases
before birth
Mare - placenta produces relaxin
Cow, sow - CL produces relaxin
Sow requires progesterone from where to uphold pregnancy?
Sow needs progesterone from CL during whole pregnancy
Mares require progesterone from where to uphold pregnancy?
placental progesterone begins to be produced in mares from D70 of pregnancy
Mare loses the CL on D150-180 of pregnancy
Ewes require progesterone from where to uphold pregnancy?
ewe placental progesterone is enough starting from D50 of pregnancy
Cows require progesterone from where to uphold pregnancy?
from CL until cow placenta produces enough progesterone from 6-8 month of pregnancy
How is parturition initially triggered?
due to less space, fetal pituitary produces adrenocorticotropin (ACTH), which induces fetal cortisol secretion
the cortisol causes a decrease in progesterone and an increase in estrogen, also causes the placenta to produce pgf2alfa which will encourage luteolysis
estrogen causes the development of more oxytocin receptors in myometrium which in turn increase contraction
Lactogen function and produced where?
Placentar lactogen prepares the mammary gland and influences fetal growth
Define gastrula.
an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells.
Endoderm develops into?
pulmonary alveolar cells, thyroid and pancreatic cells
duration from ovulation to laying of egg in birds
25 hours
(after laying, next ovulation will commence in 30 min)
active foaling should last how long?
20-30 minutes
Expulsion of placenta within 1 – 2 hours
expulsion of mare placenta should occur within what time frame?
1-2 hours
hemochorial placenta has how many divisional layers?
endotheliochorial placenta has how many divisional layers?
epitheliochorial placenta has how many divisional layers?
epitheliochorial placentas are what shape
diffuse
Horses and pigs
Cotyledonary placentas are what shape
synepitheliochorial
Ruminants (cattle, sheep,
goats, deer)
endotheliochorial placnetas are what shape
Zonary
Carnivores (dog, cat, ferret)
hemochorial placentas are what shape
Discoid
Humans, apes, monkeys and rodents
what two types of molcule cannot pass from mother to fetus
proteins, lipids and triglycerides
each are synthesized “on the other side”
(except immunoglobulins in hemochorial and endotheliochorial placentas can pass)
Immunoglobulins only cross the placenta in what types?
only in hemo- and endotheliochorial placentas
mare full estrus cycle length
on average 21 days
(Length – 19 – 23 days)
mare estrus phase length
estrous 3 - 7 days
in mares when does ovulation occur during estrus
24 – 48 h
before the end of the estrous
3 signs on imminent foaling
- Udder enlarges
- swelling of the vulva
- Once the colostrum is detected in the udder – foaling usually occurs within 24h - “waxing”
define galactopoiesis
maintenance of milk secretion
how long does maternal passive immunity persist for in neonates?
4-6 weeks
term for extra nonfunctional teats
supernumerary teats
udders can weigh up to?
up to 75 kg
Which 4 hormones affect mammary gland development?
- estrogen
- progesterone
- prolactin
- somatotropin
teat cistern volume
Duct in teat with capacity of 30-45 milliliters
bo mammary quadrant cistern volume
Holds up to 400 milliliters of milk
define galactophore
a duct carrying milk. so a milk duct
Each cubic inch of udder tissue contains how many alveoli?
1 million alveoli
each mammary gland/complex consists of?
single or multiple glands, species dependent, and associated duct system
secretory units grouped into lobes, lobules, and alveoli, with intervening connective tissue septa in which run the mammary vessels and nerves
in bovine, what structure can be found at the boundary between teat sinus and teat duct
Fuerstenberg´s rosette
at the proximal end of the papillary duct the ends of the longitudinal folds of mucosa form this radial structure
what cells squeeze milk from mammary alveoli and stimulated by what
myoepithelial cells
oxytocin stimulates
how many liters of blood is required to circulate through an udder to produce 1L milk?
1L milk needs 500 L blood to pass through udder
define isometric vs. allometric growth
isometric growth refers to the equal growth rate of body parts in comparison to the growth rate of the body
allometric growth refers to the unequal growth rate in different parts of the body in comparison to the growth rate of the body
time period for Ig to be absorbed through neonate intestinal epithelium?
during first 24-36 h after which they no longer pass through
4 main components of milk?
- fats
- lactose
- proteins
- somatic cells
name 3 types of fats found in mammalian milk
- triglycerides
- fatty acids
- glycerol
lactose consists of what sugars
D-glucose + D-galactose
name 6 proteins found in mammalian milk
- casein
- α-lactalbumin
- albumin
- β-lactoglobulin
- immunoglobulins
- Enzymes
Ideal length of milking and dry periods in dairy cattle?
305 days lactation
2 months dry period
