reproduction and development Flashcards
gonads
organs where gametes are produced
male gonads
testes
female gonads
ovaries
function of scrotum
contains testes and regulates temperature of testes
testes
male gonad where sperm is produced and testosterone is secreted
cremaster muscle
pulls testes in when temp is cold
dartos muscle
contracts during cold and makes scrotum wrinkly to reduce SA so heat is not lost
is dartos muscle relaxed or contracted in warm weather
relaxed
in what cells of the testes does spermatogenesis occur
seminiferous tubules
sertoli cells
cells of seminiferous tubules that help germ cells develop into spermatozoa
germ cells
within seminiferous tubules and develop into spermatozoa
interstitial cells of leydig
produce testosterone and androgens in response to lutenzing hormone
- adjacent to seminiferous tubules
epidimis
storage center near end of testes for maturing spermatazoa that originated in the seminiferous tubules
when spermatozoa entier the epydimis are they motile or non motile
NON-MOTILE
slowly gain motality after 2-3 months
- either ejaculated or broken down/absorbed from epydimis
in the event of ejaculation, sperm will move from the epidimis to what?
vas defernes
vas defernes
tube that runs between the epidimys and the ejaculatory duct
ejaculatory duct
fusion of vas defernes with seminal vesicles
seminal vesicles
generate liquid component of semen
- secrete fructose, vitamins, enzumes, other proteins needed for spermatozoa to live
cowper’s glands
aka bulbourthral glands
- provide pre-ejaculation lubricant for urethra and neutralize acid
ejaculation path
SEVEN UP
seminiferous tubukes
epidimis
vas deferens
ejaculatory ducts
urethra
penis
sperm
haploid gamete with flagella (microtubules) that fertalize egg
semen
alkaline liquid containing nutrients that carry sperm
azoospermia
ejaculated semen that has no sperm in it, male infertility
internal female genetalia
ovaries, fallopian tubes, uterus, cervix, vagina
external female genetalia
vulva
labia majora and minora , clit, vaginal opening
ovaries
female gonads where oogenesis occurs
contain follicles
also secrete estrogen and progesterone
ovarian follicles
each has an oocyte (immature egg cell)
what happens to ovarian follicle during menstral cycle
1 ovarian follicle releases a mature ovum into the fallopian tubes during ovulation
fallopian tubes
connect the ovaries to the uterus
- smooth muscle layer that carries out peristalsis and many cilia to move the egg from the ovaries to the uterus
uterus
where fetus develops during pregnancy
endometrium
inner epithelium of uterus
myometrium
middle layer of uterus containing smooth muscle
cervix
lower portion of uterus that connects to vaginal canal
- sperm must travel through cervix in order for fertilization to occur
spermatogensis
occurs in testes
- begins with spermatogonial stem cells and ends with mature spermatozoa
step 1 of spermatogenesis
spermatogonial cells either divide into descendent spermatogonial cells or differentiate into spermatogonia
spermatogonia
differentiate from spermatogonial cells and divide through mitosis into 2 primary spermatocytes
what sperm cells undergo meiosis
primary spermatocytes (2n) –> to become secondary spermatocytes (n)
secondary spermatocytes
haploid cells that undergo meiosis 2 to produce spermatids
result of meisosis in spermatogensis
4 haploid spermatids from each single primary spermatocyte
spermiogenesis
spermatids gain
1. formation of acrosomal cap
2. formation of tail
3. loss of excess cytoplasm
- end product: immature spermatozoa that are incapable of independent movement and are transferred to epididymis to undergo maturation
what is acrosomal cap
mature sperm cells contain this and facilitates the ability of sperm to fertalize egg
why must spermatids lose excess cytoplasm?
because sperm cells are very compact
structure of mature sperm cell
head –> contains DNA and sorrounded by acrosomal cap
mid-piece –> abundant mitochondria
tail –> motality
when does spermatogenesis occur during male lifetime?
during puberty and continues throughout life span
what is spermatogenesis highly sensistive to
temperature
oogenia
formed from primordial germ cells via gametogenesis
- ova develop through first 5 months of life
- develop into primary oocytes
primary oocytes
undergo mieosis 1 and become haploid secondary oocytes (n)
primary oocytes are frozen at prophase 1 because
it waits until puberty to commit to oogenesis
menarche
first puberty/ menstral cycle marks the resumption of oogenesis
- ovum is released and completes meiosis 1 , make 1 secondary oocyte and 1 polar body
meiosis 1 in oogenesis
secondary oocyte (receives majority of cytoplasm) –> undergoes meiosis 2
and polar body produced
meiosis 2 in oogenesis
secondary oocyte divides but is frozen at prophase 2 until fertalization occurs
- generates mature ovum and another polar body
what part of oogenesis occurs before birth
the oogonoim produces the primary oocyte (which will eventually under go meiosis 1) and is halted at the stage of the primary occyte until menarche (2n)
which part of oogenesis proceeds from puberty to menopause
primary oocyte undergoes mieosis to produce secondary oocyte and polar body
secondary oocyte undergoes meiosis 2 to produce polar body and ovum (only if fertalized)
fertilization
occurs in fallopian tubes
1. sperm cell must encounter secondary oocyte
corona radiata
layer of follicular cells sorrounding the secondary oocyte that sperm must pass through to fertalize
zona pelliculada
after passing through corona radiata, the sperm must pass through layer of glycoproteins between corona radiata and secondary oocyte
what occurs in the zona peliculada during fertilization
one of the glycoproteins binds with the sperm head and triggers the acrosome reaction (which allows the nucleus of the sperm to enter the egg)
cortical reaction
process during fertilization where the cross-link between the glycoprotein and acrosomal head that prevents fertilization by another sperm cell
zygote
fertilized ovum merges with haploid sperm cell to produce diploid zygote in the fallopian tube, must travel to uterus for further development
- defined by unicellularity
ectopic pregnancy
if the zygote does not travel from the fallopian tubes to the utereus , leads to nonviable fetus
cleavage
zygote undergoes mitotic cell divisions as it travels to uterus
embryo
multicellular fertilized zygote
morulla
once zygote has cleaved into a mass of 16 cells by 3-4 days after fertilization, tight ball
blastocyte
same as blastula
by 4-5 days after fertilization
there becomes a cavity within the morula
IMPLANTS INTO THE ENDOMETRIUM
implantation
multi-stage process that involves close communication between growing embryo and uterine tissue
- placenta begins to form from trophoblast and chorion and amnion
gastrula
from blastocyt
1. ectoderm
2. endoderm
3. mesoderm
ecotderm
skin, central nervous system, lining of mouth, anus, nostrils,
neurulation
formation of nervous system through ectoderm
first step of neurulation
formation of the notochord –> induces the formation of neural plate
neural tube
forms central nervous system
neural crest cells
peripheral nervous system
mesoderm
forms musculature, gonads, connective tissue (blood bone cartilage), kidneys, adrenal cortex
endoderm
interior lining of body, pancreas, liver, lining og GI , urinary bladder, urethra, lungs
major process of first trimester
organogenesis
placenta
supplies fetus with nutrients during pregnancy and allows gas exchange between mother and fetys
- secretes HCG
fetal hemoglobin
higher affinity for oxygen than regular hemoglobin
SRY gene
determines male sex during fetal development and produce testes
wolfian and mullerian duct
precursor structures that form into male structures after SRY male differentiation
wolfian– epididymis, vas defernes,
mullerian - lost
parturition
childbirth
which hormone induces labor contractions
oxytocin (positive feedback loop)
LH in males
causes production of testosterone in interstitial cells of leydig
LH in females
causes ovaries to produce estrogen
FSH in females
maturation of ovarian follicule
FSH in men
spermatogenesis in seminiferous tubules
ovarian cycle
follicular phase then ovulation then luteal pjase
1 ovum is released every cycle
follicular phase
follicle matures and releases the egg during ovulation
luteal phase
refers to what happens after the egg is released , follicle is tranformed into corpus luteum
corpus luteum
secretes progesterone and helps maintain uterine lining , decays at end of the cycle
menstration
right before follicular phase when passed uterine lining is shed
proliferative phase
uterine endometrium is built up
what hormone dominates at begining of follicular stage
FSH
estrogen gradually increases
lh surge
induces ovulation and formation of corpus luteum
luteal phase
increased progesterone
no impantation
negative feedback of progesterone on LH and corpus luteum disintegrates , progesterone not being produced
how is corpus luteum maintained during implantation
embryo secretes HCG to keep sustained progesterone levels
what hormones can placenta secrete
estrogen and progesterone (by 2nd tri) so no longer need hcg from embryo
