R E P R O D U C T I V E Flashcards
list the structure through which sperm pass during development and ejaculation
- epididymis
- ductus (vas) deferens
- ejaculatory duct
- urethra
which organs are responsible for gamete production in males and females?
females: ovaries make ova
males: testes make sperm
spermatocyte development
- spermatogonia (type A&B)
- primary spermatocyte
- secondary spermatocyte
- early spermatids
- late spermatids
- spermatozoa
oocyte development
- oogonium
- primary oocyte
- secondary oocyte + first polar body
- second polar body + ovum
Compare and contrast the timing of events during the development of spermatocytes and oocytes
at puberty in males, spermatocytes go through meiosis I and II
before birth, oocytes go through mitosis and at birth primary oocyte enters meiosis I arrested in prophase I, secondary oocyte arrested in metaphase II
mitosis
2 diploid cells formed from diploid cell (one division)
for development of multicellular adult from zygote
produces cells for growth and tissue repair as multicellular adult develops
- ensures genetic make-up of all body cells is constant
meiosis
four haploid cells formed from diploid cell (2 divisions)
produces cells for reproduction (gametes)
introduces genetic variability in the gametes and reduces chromosomal number by half (haploid - 23), so that when fertilization occurs, the normal diploid chromosome number is restored (46)
when does meiosis occur in humans?
when the human body is producing gametes
what are the 2 gonadotropins?
- FSH
2. LH
FSH
stimulate follicles in ovaries to grow, mature, and secrete sex hormones
LH
stimulate thecal cells to secrete androgens, surge cause ruptured follicle involved in ovulation
prostate gland
the prostate gland’s milky, slightly acidic fluid, which contains citrate, enzymes, and prostatic-specific antigen (PSA), accounts for 1/3 of semen volume; activates sperm
bulbo-urethral gland
produce thick, clear mucus that neutralizes acidic urine and lubricates urethra prior to ejaculation
seminal gland
secretes 60% of volume of semen
stratum functionalis
endometrium; undergoes cyclic changes in response to ovarian hormones and is shed during menstruation
stratum basalis
endometrium; forms a new functionalis after menstruation ends and does not respond to ovarian hormones
Describe the phases of the menstrual (uterine cycle)
1. Menstrual phase Days 1-5 Uterus sheds functional layer of endometrium 2. Proliferative (preovulatory) phase Days 6-14 Endometrium rebuilds 3. Secretory (postovulatory) phase Days 15-28 Endometrium prepares for implantation of embryo
Describe the phases of the ovarian cycle
follicular phase
period of follicular growth (days 1-14); form antrum
luteal phase
period of corpus luteum activity (days 14-28); secrete progesterone/estrogen
ovulation
occurs midcycle; boundary btw the two, ovary wall ruptures and 2nd oocyte is expelled surrounded by corona radiata
Describe the hormonal and vascular event that causes menses
If fertilization does not occur, progesterone levels fall, depriving the endometrium of hormonal support
spiral arteries begin to kink and go into spasms and endometrial cells begin to die
The functional layer begins to digest itself
Spiral arteries constrict one final time then suddenly relax and open wide
The rush of blood weakens and fragments capillary beds and the functional layer breaks down
List in order all of the structures that the oocyte encounters from ovulation to implantation
- ovary
- pelvic cavity
- fimbriae
- infundibulum
- ampulla
- isthmus
- lumen of uterus
- endometrium of uterus
Which characteristics signify the imminent rupture of a Graafian follicle?
large fluid filled Antrum (follicular phase)
Describe the events involved in fertilization.
- capacitation has to happen so that freshly ejaculated sperm can penetrate an oocyte
- capacitation enhances motility of the sperm and the membranes of the sperm head becomes fragile to allow release of hydrolytic enzymes from acrosome
- hyaluronidase on the surface of the sperm digests intercellular attachments between cells of the corona radiata and cause them to fall away
- after penetrating the corona radiata, sperm heads bind to receptors on zona pellucida
- acrosomal reaction: acrosomal enzymes (hyaluronidase, acrosin, proteases, etc.) are released and digest away the zona pellucida
- once a path through the zona pellucida is cleared, the back portion of the sperm head binds to plasma membrane of the oocyte
- the oocyte membrane forms microvilli that encases the sperm head
- cytoplasmic contents of the sperm enters to oocyte, and its plas
Following fertilization, how long is it before the zygote divides into two cells?
12-24 hrs
What is the term for the cell divisions taking place following fertilization? What is each new cell called?
cleavage; blastomere; morula; blastocyst (“hatches” from zona pellucida”; trophoblast cell (flattened outer layer) with inner cell mass
gastrulation
Process by which two-layered embryonic disc becomes three-layered
Involves cellular rearrangement and migration
Begins with primitive streak formation
Groove with raised edges appears on dorsal side of embryonic disc
Extends from caudal toward cranial end
Establishes longitudinal axis of embryo
Epiblast cells migrate medially to enter primitive streak
First cells to enter primitive groove displace hypoblast cells and become the definitive endoderm
Cells that follow become the middle germ layer - the mesoderm
Cells that remain in epiblast are now termed the ectoderm
All body organs derive from these three germ layers.
Name the four extraembryonic membranes and their functions or what they develop into
here are four extraembryonic membranes that form during the first 2-3 weeks of development:
- chorion helps to form the placenta, and encloses embryonic body and all other membranes
- amnion contains amniotic fluid
- yolk sac forms part of the gut
- allantois is the structural base for the umbilical cord
During labor and birth what are the sources and signals for more oxytocin?
Produced initially by fetal cells and stimulates uterine muscle contraction
- Distention of cervix triggers hypothalamus to signal oxytocin release from posterior pituitary; estrogens from placenta induce oxytocin receptors in uterus
What are the major stages of labor during pregnancy and what is the term for false labor?
- Dilation
- Expulsion
- Placental Stage
False contractions are known as: Braxton Hicks contractions are weak, irregular contractions that occur due to estrogen’s irritating effect on uterine muscle
