Reproductive Toxicology Flashcards
final exam
what is the reproductive cycle?
- gamete production and release
- fertilization
- zygote transport
- implantation
- embryogenesis
- fetal development
- parturition
- Lactation and postnatal development (rest period for humans)
- growth and development
- sexual maturation
what are the different testing phases for a reproductive toxicant? what do each contain?
- Fertility Segment (includes gamete production and release, fertilization, zygote transport, implantation)
- Embryotoxicity, Teratogenicity (includes embryogenesis, fetal development, parturition)
- Pre- postnatal toxicity (includes Lactation and postnatal development, growth and development, sexual maturation)
explain the fetal prepubertal female germ cell development
- all oocytes are made during gestation (many actually die before birth)
- germ cell becomes primordial follicle (after a few steps), where they enter prophase
- but, it then stays dormant until puberty
explain the pre-ovulatory phase of female germ cell development.
starts when puberty begins:
- becomes a primary follicle
- then through action of FSH/LH, becomes early secondary follicle (and can then secrete androgens and estrogens)
- becomes advanced secondary follicle
- 2ndary oocyte with polar body (start of meiosis II)
explain the ovulatory phase of female germ cell development.
- becomes ovulatory follicle:
- if fertilized, becomes corpus luteum
- if not, corpus albicans
explain the female hormone signaling pathway starting from the CNS.
- CNS signals to hypothalamus
- hypothalamus releases GnRH, which signals anterior pituitary
- releases LH (signals to Theca cells), FSH (signals to granulosa cells), and prolactin (signals corpus luteum)
- granulosa cell makes estradiol and corpus luteum, progesterone.
- a) both signal to vagina, cervix, uterus, and oviduct
- b) also they both negative feedback on hypothalamus and anterior pituitary.
explain the menstrual cycle
increase of FSH as follicle matures, until there is a surge (means that there is a surge of estradiol), and around the same time, there is the LH surge, which marks the release of the egg. Now the corpus luteum is developing and releasing high amounts of progesterone. Eventually, it dies, which decreases the progesterone levels (then menses occurs)
potential useful targets for female reproductive toxicants (12).
- body weight
- ovary
- hypothalamus
- pituitary
- endocrine
- oviduct
- uterus
- cervix
- vulva
- vagina
- fertility
- IVF
what are some things we can measure/look at in the ovary for toxicants? (9)
- organ weight (helpful but there is a natural decline so hard to know if the change is relevant)
- histology
- number of oocytes
- rate of follicular atresia
- follicular steroidogenesis (look at progression of folllicles)
- follicular maturation
- oocyte maturation
- ovulation
- luteal function
what are some chemicals linked to adverse reproductive outcomes in females? (8)
- phytoestrogen: natural products that have estrogenic activity
- heavy metals (cooper, cadmium, lead)
- solvents (benzene, chloroform)
- industrial chemicals
- pesticides
- cigarette smoke (major effects on fertility)
- vaping (less evidence but clearly an effect on follicles to grow normally)
- chemotherapeutic agents: granulosa cells are those that grow and secrete estrogen, these will inhibit cell division, which prevents the granulosa cells from dividing, which will decreases estrogen (and prevent ovulation – infertility)
- chem agents: prednisone, 5-FU, cyclophosphamide, …
what are the feedback mechanisms operating in the male?
- LH signals to Leydig cells, that makes testosterone, and it can signal back to anterior pituitary and hypothalamus
- FSH signals to Sertoli cells, that mike inhibin, that signals back to anterior pituitary
where are Leydig cells located?
in between seminiferous tubules, so high testosterone concentration there
how long is spermatogenesis in humans? what about other species?
- 64 days
- varies: rat is between 48-52 and rabbit is 49 for example
potential target sites for male reproductibe toxicants
- liver, nutrition, testicular vasculature, pituitary, CNS, epididymal maturation, fertilization, pineal
- sperm motility, chromatin integrity
- semen
- accessory glands
which part of the germ line cycle does cyclophosphamide affect?
when it loses some of its repair mechanisms in the beginning