DAT Embryology Flashcards
Fission
separation of an organism into
two new cells (amoeba)
Budding
occurs when a new individual
grows from an existing one and then
splits off (hydra)
Fragmentation + Regeneration
when a
single parent breaks into parts that
regenerate into new individuals (sponge/
planaria/starfish)
Parthenogenesis
process in which egg
develops without fertilization, resulting in
an adult that is either haploid or diploid
(honeybees, wasps, ants, some lizards,
and hammerhead sharks)
Ovary
- ova, or eggs, are produced here,
and each female has two ovaries
Oviduct (fallopian tube/uterine tube)
allows for eggs to move from the ovary
to the uterus, with one oviduct for each
ovary (2). Fertilization occurs here!
Uterus
muscular chamber where
development of the embryo occurs until
birth. A fertilized ovum implants
(attaches) on the inside uterine wall, or
endometrium, on day 6 after fertilization
Vagina
at birth, the fetus passes
through the cervix, an opening in the
uterus, and out of the body
Testis
each consists of seminiferous
tubules for production of sperm, and
interstitial cells (Leydig cells) that
produce male sex hormones
testosterone and androgens at the
beginning of puberty. These hormones
are secreted in the presence of LH.
Sertoli cells
are stimulated by FSH
and serve to surround and nurture
sperm, as well as secrete peptide
hormone inhibin, which acts on the
anterior pituitary to inhibit FSH
release
Scrotum
testis are located here;
provides an external cavity, about
2o
C lower than the body
temperature, for sperm production.
Epididymis
a coiled tube attached to
each testis that serves as the site for
final maturation and storage of sperm
Vas deferens
transfers sperm from
one epididymis to the urethra
Seminal vesicles
two glands that, during
ejaculation, secrete into vas deferens and
provide mucus (liquid for sperm), fructose
(energy for sperm), and prostaglandins
(stimulate uterine contractions that help
sperm move into uterus).
Prostate gland
secretes milky alkaline
fluid into urethra and neutralizes acidity of
urine that may still be in the urethra, as
well as acidity of the vagina. This gland
also neutralizes seminal fluid, which is too
acidic from metabolic waste of sperm
Bulbourethral (Cowper’s) glands
secrete small amount of thick mucus of
unknown function into urethra
Sperm
are compact packages of DNA
specialized for effective male genome
delivery.
parts of sperm
head, mid piece, tail
Sperm head
haploid (23
chromosomes); at tip is acrosome, a
lysosome-like organelle containing
enzymes (hyaluronidase), which are
used to penetrate the egg. The
acrosome originates from Golgi body
vesicles that fuse together, and only
the nuclear portion of the sperm
enters the egg
Mid-piece
flagellum (9+2
microtubule array) arising from one
member of centriole pair, and contains
lots of mitochondria
Tail
remainder of flagellum; sperm is
propelled by whiplike motion of tail
and mid-piece
Gametogenesis describes
the meiotic cell
divisions that produce eggs (oogenesis) and
sperm (spermatogenesis).
Oogenesis
begins during the female
embryonic development (before birth).
Oogonia (fetal cells) undergo mitosis and
become primary oocytes. These primary
oocytes begin meiosis, but remain in
prophase I until puberty. During puberty,
one primary oocyte is selected and
stimulated via FSH to continue its
development through meiosis I during
the ~28 day menstrual cycle.
Ovulation
releases the secondary
oocyte from a vesicular follicle, which
is stimulated by an LH surge. If this
oocyte is fertilized by a sperm, the
oocyte completes meiosis II, and the
resulting ovum/egg becomes diploid.
The polar body degenerates.
Spermatogonia cells
undergo mitosis
and become primary spermatocytes.
These primary spermatocytes undergo
meiosis I and form two secondary
spermatocytes, which undergo meiosis
II to become four spermatids.
Sertoli cells
are found in seminiferous
tubules, provide nourishment, and
“nurse” spermatids as they differentiate
into mature spermatozoa (sperm). The
sperm complete maturation (gain
motility and are stored) in the
epididymis.
Semen
the combination of
spermatozoa and fluids that leave the
penis upon ejaculation.
Capacitation
- the penultimate step in the
maturation of the spermatozoa while in
the vagina that allows for egg
penetration. This is the final maturation of
spermatozoa.
Female reproductive cycle
consists of
ovarian cycle (in the ovary) and the
menstrual cycle (involves uterus)
Menstrual cycle
is divided into the
proliferative, secretory, and
menstruation (menstrual flow)
phases. Menstruation begins with
the disintegration of the
endometrium (menstrual flow phase).
steps of menstrual cycle
Hypothalamus and anterior
pituitary initiate, Follicle develops, LH surge, Development of endometrium, Corpus luteum disintegrates (no
longer maintained by LH)
Ovarian cycle phases
Follicular phase, Ovulation, Luteal phase,
Follicular phase
development
of egg and secretion of
estrogen from follicle [ends at
ovulation]
Ovulation
mid-cycle release of
egg
Luteal phase
secretion of
estrogen and progesterone
from corpus luteum after
ovulation [shedding of the
uterine lining lasting
approximately 5 days]
progesterone serves to…
develop and maintain the endometrial wall. also inhibits lactation during pregnancy
Female hormonal contraception
estradiol and/or progesterone are
spiked artificially high → negative
feedback suppresses LH/FSH surge
→ no ovulation can occur → no
fertilization possible
Male contraception
a pill would
interfere with LH and FSH to
decrease sperm production
