Female reproduction Flashcards
parthenogenosis
growth and development without fertilization by a male
estrus
period when female will permit copulation; aka being in “heat”
- estrus female’s will seek out males, initiate copulation,, maintain close proximity to males
- estrus females more attractive (urine/odors), mounted by males preferentially
- mating behavior is tightly coupled with ovulation
- mating behaviors (estrus) occur when successful fertilization of the ova is most likely
Hormonal action
- hormones change the probability that specific stimuli will elicit particular behaviors that lead to successful copulation
- Input systems: acuity, sensitivity, and efficiency of sensory systems are enhanced by reproductive hormones (E females better able to detect and respond to males)
- CNS: females motivation, attention, and perception change as sex steroid levels fluctuate
- effectors: way a female moves and responds to stimuli changes
- behavior: her own behavior, as well as stimuli F emits (odors, chemosensory signals) influence how the males behave, the way males behave may feed back to alter her own behavior
primordial follicle
consists of oocyte+ singular layer of granulosa cells
primary follicle
consists of oocyte, zone pellucida, granulosa cells (more layers)
pre-antral follicle
oocyte, zona pellucida, granulosa cells, developing thecal cells
antrum
space that develops between the ovum and granulosa cells; fills with a fluid termed liquor folliculi (follicular fluid)
graafian follicle
dominant follicle, one that is ovulated; enlarges due to expanding/growing antrum; enzyme breaks down the wall between the mature ovary and follicle (induced by LH)= bursting of oocyte from follicle= ovulation
corpus leutum
degenerated granulosa and thecal cells form the CL, secretes progesterone which maintains the uterine lining needed to sustain a pregnancy; will degenerate into the CA if there is no successful fertilization
corpus albicans
degenerated CL
granulosa cells
surround the oocyte; grow in number via mitotic division as the follicle matures
- secrete activin, inhibin, E’s, progesterone
- acted upon by FSH and LH
FSH: convert androstenedione–> estrogen via aromatase
LH receptor stimulation–> progesterone production–> behavioral estrus
pre-ovulatory: FSH–> activin–> +FSH
post-ovulatory: FSH–> inhibin–> -FSH
thecal cells
surround granulosa cells and secrete estrogens
- acted upon by LH (cholesterol–> androstenedione)
- ??does LH stimulate E release in thecal cells?
oogenesis
development of the ovum
oogonium
immature female reproductive cell that gives rise to primary oocytes by mitosis; 3rd prenatal month
primary oocyte
immature egg cell; 6th prenatal month–> does not undergo meiosis 1 (stuck at prophase 1) until puberty (first period)
secondary oocyte
product of meiosis one–puberty has begun, and meiosis continues as folliculogenesis proceeds as stimulated by FSH
ovum development
ovum is the product of fertilization and meiosis 2–an ovum will NOT DEVELOP WITHOUT FERTILIZATION
-ovum will begin to undergo cell divisions into a mature egg, where it will eventually implant into the uterine lining
ovulation
release of an ovum from a follicle and ovary induced by an LH surge
zygote
fertilized egg: will begin going under cell division in the fallopian tubes prior to implantation
blastocyst
develops from the zygote after 5 days of cell division; goal is to implant into the cell wall where it will develop into an embryo and support the uterus during a pregnancy
vaginal lavage
developed by Stockyard and Papanicolaou–allows us to tell the stage of ovulatory cycle even when the ovary is internal
- swab cells of the vaginal lumen after a lavage and examine the cells microscopically
- reveals changes in cellular contents of vaginal lumen that occur every 4-5 days
pap test
developed by Papincolaou: cells from the cervix examined to screen for cervical cancer
relationship between ovarian cycles, vaginal cytology, hormones, and behavior
cyclic changes in ovarian cycles and structure correspond with vaginal cytology, hormone levels, and behavior
-behaviors that correspond with vaginal and ovarian cytology are influence by ovarian steroids (ie estrogens and progesterone)
vaginal estrus
- post ovulation
- cornified epithelial cells
- recently ruptured follicle, corpus leutum
- no reproductive behavior
diestrus 1/metestrus
- follicular development of primary follicle
- majority leukocytes
- no reproductive behavior
diestrus 2
- follicular development of secondary follicle
- no reproductive behavior
vaginal proestrus= behavioral estrus
- pre-ovulation: Graafian follicle
- reproductive behavior: lordosis!
- induced by estrogens (mediated by LH/FSH) and progesterone (Graafian follicle)
2 cell theory: LH, FSH, thecal and granulosa cells
LH: induces formation of androstenedione from cholesterol in thecal cells
FSH: induction of aromatase system–> converts androstenedione produced in thecal cells–> estrogens
Positive Feedback: pre-ovulation
Estrogen: secreted from granulosa cells; feedback on AP and hypo (specifically AVPV)–> increase GnRH and LH/FSH release
Activin: secreted from granulosa cells: feedback on hypo to increase FSH secretion
Negative feedback: post-ovulation
Estrogen: high concentrations of estrogen feedback on AP and hypo (specifically, ARC nucleus) to decrease GnRH and LH/FSH
Progesterone: released from CL; feedback on hypo and AP
inhibin: released from granulosa cells; feedback on hypo to decrease FSH
AVPV and positive feedback
estrogen receptors located on the AVPV and synapse onto GnRH receptors located in the hypothalamus–stimulation of AVPV receptors by E releases kisspeptin–> terminates on hypo and leads to GnRH release–> LH/FSH release in AP–> E/P release in ovaries
ARC nucleus and negative feedback
estrogen receptors located on ARC nucleus inhibited by estradiol which is exerting a negative feedback–> inhibition of kisspeptin–> inhibition of GnRH release–> inhibition of LH/FSH release
pseudopregnancy
do NOT happen in humans (humans have a spontaneous corpus leutum phase); happens in species who have induced luteal phases
- time when there is a corpus leutum and buildup of the uterine lining in the absence of pregnancy
- uterus ready for the blastocyst, but no ovum
type 1 reproductive cycle
spontaneous ovulation
spontaneous CL/pseudopregnancy
2-5 weeks; 5>
ex: humans, guinea pigs, apes
type 2 reproductive cycle
induced ovulation
spontaneous CL
length: 3-5 weeks (ex: cats)
type 3 reproductive cycle
spontaneous ovulation
induced CL
length: <1 week
ex: rats
attractivity
stimulus value of a female, how attractive a female is to a male conspecific
- extent to which a male prefers one female over another female
- hypothetical, has to be inferred by the researcher
ways to measure attractivity in different species
- rhesus monkey: mounts/min= mounting ratio
- rats: tethering and 3 chamber preference test
- horse: Flehman response
- baboon: male acceptance ratio–# of female solicitations/male mounting
attractivity and hormones
estrogens increase attractivity
- morphological changes associated with ovulation: ex–baboon swelling of the perineum
- chemosensory cues: chemical cues are important in establishing stimulus bases of attractivity (ex: garter snakes, horses)
- behavior
perceptivity
extent to which a female initiates copulation; behaviors that initiate copulation= FLIRTING
- reflect a female’s overt behavior and motivational state
- ex: rats: hopping, darting, ear wiggling
- ex: rhesus monkey: number of solicitations
- ex: rhesus monkey: bar pressing
receptivity
RESPONSIVENESS to sexual initiation, reflected by the adoption/reaction necessary for a fertile copulation, reflected by species-specific sexual position
-reflection of the stimulus value of the female for eliciting intravaginal ejaculations
- ex: # of ejaculations, or ejaculation time in rhesus monkeys
- ex: rats: lordosis quotient= # of successful lordosis/10 mounts
- ex: hamsters: amount of time spent in lordosis
role of estrogen and progesterone in lordosis: rats
estrogen and progesterone needed for the full expression of proceptive and receptive behaviors
- OVX+ E (no P)–> weak receptive, no preceptive
- OVX+E+P–> full receptive and proceptive
relationship between E, P, gene transcription
estrogen given to rats 48 hrs prior to testing because E acts as a transcription and translation factor for progesterone receptors (so by giving estrogen, you are also creating progesterone receptors)–> so in an OVX F, progesterone need not be given until 5 hrs prior to testing
VMN and estrogen
- estrogen acts on the VMN to stimulate lordosis behavior
- example of how hormones act of the CNS to influence reproductive behavior
- study 1: bilateral injections of estrogen into progesterone-treated, OVX rat–> full lordosis behavior
- study 2: OVX+E+P+anti-E–> no lordosis behavior
estrogens mechanism of action on the CNS
receptors, enzymes, transporters, ion channels, NT systems–> impact the female rat’s neural responsiveness to male stimulation–> increased electrical activity and action potential–> lordosis
acetylcholine and lordosis
- muscarinic receptors
- OVX+E+acetylcholine–> lordosis
- OVX+E+acetylcholine antagonist–> decreased lordosis
lordosis neural mechanisms of action
- E acts on the flanks during estrus to increase their size, increasing F sensitivity to male tactile stimulation
- flanks stimulated by male
- sensory input will make its way to the spinal cord and midbrain central gray
- estradiol is acting on the VMN to stimulate lordosis behavior–when estradiol concentrations are high, it will activate the spinal motor neurons necessary to innervate the back muscles
- information travels down a descending pathway of the spinal cord, where it makes its way to synapses of motor neurons that connect to deep back muscles
- lordosis behavior
pacing
rewarding to female rats because it enhances the likelihood of getting pregnant
-female controls the duration of interval time between sexual interactions; timing depends on KIND of sex interaction (mounting–> intromission–> ejaculation)–> reveals females can discriminate vaginal stimulation
vaginal code
optimal pattern of stimulation to produce offspring
paced mating, prolactin, and progesterone
pacing behavior–> release of prolactin–> maintenance of corpus leutum–> release of progesterone–> maintenance of uterine lining–> pregnancy maintenance and increased likelihood of maintaining a pregnancy if there’s a successful fertilization
