Test 4-2 Flashcards
hypothalamus secretes
gonadotropin releasing hormone - secreted by neurosecretory cells–> primary cap plexus—> hypophyseal protal veins –> secondary cap plexus —> (goes to ant pituitary cells) the basophils (gonadotropes)
basophils (gonadotrope cells)…
part of ant pituitary - synth and secrete folicle stim hormone and lutenizing hormone
FSH
- secreted and synth by basophils(gonadotropes).
- Stimulates maturation of an ovarian follicle and prepares the enclosed oocyte for ovulation
LH
- secreted and synth by basophils(gonadotropes).
- LH spike stimulates ovulation- release of egg from ovary
granulosa cell
surround maturing oocyte in prep for ovulation
-produce and secrete estrogen and progesterone= influence the uterine lining (the endometrium) to prepare for possilbe implantation
following ovulation…/
the granulosa cells remain behind ni the ovarian cortex form the corpus luteum= temporary endocrine gland
if fertilized then…
- corpus luteum is maintianed (CL of preganancy) via hCG released by the well-developed syncytiotrophoblast of the chorian (part of placenta).
- Corpus luteum produces estrogen and PG to maintain the endometrium and pregnancy
if NOT fertilized then…
- CL of menstruation produced estrogen and PG for 14 days to maintain endometrial lining.
- then it degenerates into corpus albicans and endometrium is shed
Ovary - germinal epithelium
simple squamous or cuboidal epithelium.
-thin and clear
cancers most ofetn arise from which lyer/
germinal epithelium - 70% of cancers
ovary- tunica albuginea
- (whitish capsule) dense irregular collagenous CT,
- protective.
- structural integrity
ovary - Cortical region
- connective tissue stroma (framework) with smooth muscle fibers and many ovarian follicles. Is compact.
- Oogenesis: oocytes (eggs) mature here.
ovary - Medullary region
- is the core of the ovary.
- It consists of a stroma of loose connective tissue, and numerous blood vessels, lymphatic vessels and nerves.
- Is spongy.
- nourishment for ovary
OOGENESIS
the process by which mature ova are produced.
Sex cells
- gametes = egg, sperm
- contain 23 chromosomes,
- are haploid n
Somatic cells
- body cells
- contain 46 chromosomes
- are diploid (2n)
Meiosis
is a reduction division which occurs only in germ cells
oogenesis and meiosis
-2 sequential meiotic cell divisions = msingle mature ovum and 3 polar bodies
prenatal primordial germ cell duplication (prior to meiosis)
46 single chromatid chromosomes (2n - 2d) –> duplicate during the S-phase
of Interphase —> form 46 double chromatid chromosomes (2n - 4d)
Meiosis I
- begins prenatally (during embryonic period
- At the onset of Meiosis I, there are 46 (double chromatid) chromosomes in the developing primordial germ cells.
- Meiosis I begins and then STOPS at PROPHASE and remains “suspended” / “dormant” in prophase I until just before ovulation (sometime between the ages of 12 - 50 years).
- Note that once a primordial germ cell enters Meiosis I, it is referred to as a primary oocyte, and at prophase I, it is still (2n - 4d), since Meiosis I has not been completed yet.
OVaries at Birth
- AT BIRTH, 1* oocytes: are the only cells within “primordial follicles” in the newborn ovarian cortex, suspended in prophase I.
- These 1* oocytes remain dormant in prophase I for about 12 - 50 years, depending on when the follicle around each oocyte matures and the oocyte is ovulated.
prior to ovulation
- Prior to ovulation of an oocyte, Meiosis I RESUMES.
- It progresses from Prophase I through Metaphase I, Anaphase I and Telophase I, COMPLETING Meiosis I.
- During Anaphase I, the homologous, double chromatid chromosome pairs – separate – and each resultant cell inherits half of the chromosomes = 23 (double chromatid,) chromosomes.
- At the end of Meiosis I the resultant cell is called a 2* oocyte and a polar body#1
Meiosis II
- prior to Meiosis II there is NO DNA replication = NO INTERPHASE
- Begins immediately after Meiosis I (prior to ovulation, while the oocyte is still in the ovarian cortex).
- This division will progress to and will STOP and remain suspended at Metaphase II, in a mature (Graafian) follicle.
AT OVULATION:
-At ovulation, the 2* oocyte is in Metaphase II and is released into the uterine tube hovering over the ovary.