reproductive hormones & gamete development Flashcards
hypothalamus secretes:
releasing hormone
anterior pituitary cells & what they secrete
- somatotrope cells ➞ secrete growth hormone (GH)
- corticotrope cells ➞ secrete adrenocorticotropic hormone (ACTH)
- thyrotrope cells ➞ secrete thyroid-stimulating hormone (TSH)
- lactotrope cells (aka manotropes) ➞ secrete prolactin (PRL)
- key lactogenic hormone for lactation
- gonadotrope cells ➞ secrete gonadotropins (FSH, LH)
posterior pituitary secretes
oxytocin
gonadotropins
peptide hormones that regulate testiclar & ovarian fx
* FSH (follicle stimulating hormone):
* M: stimulates sertoli cells in testes ➞ supports sperm production
* F: induces growth of follicles in ovaries
* LH (luteinizing hormone):
* M: stimulates testosterone prod by leydig cells in testes
* signals androgen production which causes 1º & 2º sex characteristics
* F: stimulates estrogen prod in ovary & ovulation
* GnRH (gonadotropin releasing hormone): released by hypothalamus that stimulates release of FSH & LH from pituitary
1º sex characteristics: F & M
F:
- vagina
- uterus
- fallopian tubes (oviducts)
- clitoris
- cervix
- ability to bear children
M:
- penis
- scrotum
2º sex characteristics: F & M
F:
* enlarged breasts
* widening of hips
* pubic hair
M:
* facial hair
* adam’s apple
* pubic hair
spermatogenesis
formation of sperm
* spermatogonium: diploid undifferentiated stem cell that becomes haploid spermatogonium
* occurs in waves ➞ continual process that ensures reproductive readiness
* occurs within seminiferous tubules
* leydig cells in intersticial tissue site of testosterone prod
* sertoli cells line edge of seminiferous tubules ➞ guard & directionality
1. diploid spermatogonium multiply by meiosis at basal lamina (outer edge of seminiferous tubule) ➞ primary spermatocyte
2. primary spermatocyte go through meiosis I ➞ secondary spermatocyte
3. secondary spermatocyte go through meiosis II ➞ spermatid = haploid daughter cell
4. spermatid goes through morphological changes ➞ spermatozoon at lumen lining
testosterone
- growth: muscle & reprod tract
- body composition: more muscle, less fat
- behavior: ↑ aggression & libido
- contributes to boar taint in pigs ➞ urine/fecal smell in non-castrated meat
- androstenones: testicular steroid w/ pheromone fx & urine-like odor
- skatole: product of bacteria in gut
- androstenone prevents skatole from being broken down ➞ goes to fat & stays
- does not happen in F ➞ no testosterone ➞ skatole can be broken down in liver & metabolized
oogenesis
production of haploid gamete (ovum/egg)
- occurs in ovaries
- starts when F is still fetus in mother’s womb
- F is born with all eggs she will ever have
- occurs at cortex
- oogonium undergoes mitosis: homologous chrom replicate ➞ 1º oocyte
- primary oocyte arrests in meiosis I before birth
- 1º oocyte not evenly divided ➞ F must invest all resources in 1, other = polar body
- 2º oocyte = antral/graafian follicle
- meosis II only proceeds after fertilization ➞ 2nd polar body
folliculogenesis
- follicles on outer edge of ovary = cortex
- middle of ovary = medulla ➞ blood/blood vessels
- cyclic
1. eggs in primordial follicle: flattened layer of cells surrounding primary oocyte
2. primary follicle: single layer of cells surround primary oocyte
3. secondary follicle: primary oocyte + 2 layers of cells
4. tertiary follicle: antrum cavity forms ➞ fluid-filled cavity nourishes primary oocyte & helps with communication
5. antrum or graafian follicle: meiosis I completes ➞ secondary oocyte (antral/graafian follicle) ruptures & releases into ovary = ovulation
6. cells from follicle differentiate & form corpus luteum (CL) = luteinization ➞ will stay if pregnant & produce progesterone
7. hormones signal that secondary oocyte is not fertilized ➞ CL regresses into corpus albicans
F reprod hormones
ovaries = site of oogenesis & F sex hormone production
* have multiple follicles developing simultaneously at diff stages
* estrogen made by follicle ➞ helps w/ development & fx of reprod tract & important when F is in heat/ready to breed
* progesterone: made by CL to prepare for & maintain pregnancy
* prepairs uterus for implantation
* keeps uterine envir optimal for egg
* prevents uterus from contracting & expelling egg
A: amniotic cavity
B: amnion
C: chorion
D: allantois
E: chorioallantois
F: yolk sac
blue: amniotic cavity
A: zona pellucida
B: morula
C: blastocyst
D: inner cell mass
E: blastocoele
F: trophoblast
A: luteolysis
C & F: progesterone
D: estrogen
B: follicular phase
E: ovulation
G: luteal phase
A: developing antral follicle (tertiary)
B: secondary follicle
C: primary follicle
D: primordial follicle
G & F: theca
H: ovulating follicle
I: CL
J: corpus albicans
K & L: zona pellucida
E: granulosa
M: medulla
N: cortex
A: cumulus cells
B: zona pellucida
C: follicle
D: theca
E: gransulosa cells
F: oocyte
center: antrum
A: primordial follicles
B: primary oocyte
C: follicle cells
D: primary follicle
E: zona pellucida
G: granulosa cells
H: secondary follicle
I: corpus albicans
J: antrum
K: CL
L: developing CL
M: cortex
N: graafian/antral follicle
O: coeona radiata
P: medulla
A: diestrus
B: proestrus
C: estrus
D: metestrous
E: follicular phase
F: progesterone
G: estrogen
H: LH
I: FSH