Mitosis vs Meiosis
Mitosis:
- Creates identical diploid daughter cells of parent cell.
Meiosis:
- Chromosomes do not duplicate before daughter cells divide.
- Half of total chrom. go to each daughter cell (haploid).
- At random which chrom. go to which daughter cell.
Spermatogenesis: What is it? What is the process?
- Production of male sex cells.
Process:
1. Primary spermatocyte divides by meiosis into secondary spermatocytes.
2. Secondary spermatocytes divide by mitosis into four spermatids.
3. Spermatids grow tails & physical changes making them spermatozoa (half are X, half are Y).
4. When fully developed, they detach & carried to epididymis for storage then ejaculation.
Oogenesis: What is it? What is the process?
- Production of female sex cells.
Process:
1. Primary oocyte divides by meiosis into large secondary oocyte & small “polar body”
(Each has the haploid chrom. #)
2. Secondary oocyte & polar body divide by mitosis into an ovum and three polar bodies.
3. Three polar bodies will not develop, ovum will.
Spermatozoa structure (4)
- Acrosome: contains digestive enzymes to help reach & penetrate ovum.
- Head: contains nucleus of cell.
- Neck “midpiece”: large concentration of mitochondria in a spiral form.
- Tail: muscle like contractile fibrils. Produces whiplike movement (locomotion) to propel forward.
Components of male reproductive system (2)
- Penis
- Testes
Testes structure and function
Function:
- Produce sperm and hormones.
Structure:
- Outside abdomen in inguinal region.
- Housed in skin sac; scrotum.
Penis function
- Erection: parasympathetic reflex trig by sexual stim.
- Involves olfactory cues & behavioral changes.
- Arteries dilate, increase blood flow to penis. - Ejaculation: reflex impulse of semen.
- Semen moves from accessory repro glands into pelvic portion of urethra.
- Rhythmic contractions of urethra pump semen out & into female repro tract.
Penis structure (6)
- Roots: bands of connective tissue (crura) that attach penis to the brim of the pelvis.
- Body: two bundles of erectile tissue (corpus cavernosum urethrae & corpus cavernosum penis).
- Glans: distal end; numerus sensory nerves.
- Prepuce: sheath of skin that encloses the penis when flaccid.
- Os penis: bone in the penis; urethra run thru groove on ventral side.
- Bulb of glans: enlargement towards rear of the glans. Engorges w/blood, “ties” w/muscle contractions, & subsides 15-20min.
Components of female reproductive system (7)
- Ligaments
- Ovaries
- Oviducts
- Uterus
- Cervix
- Vagina
- Vulva
Ligaments (3) of female repro system
- Broad lig: sheets of peritoneum.
- Suspends ovaries, oviducts, & uterus.
- Contains blood vessels & nerves. - Suspensory lig of the ovary. Ovarian end of broad lig attached to body wall in area of last rib.
- Round lig of the uterus. Fibrous tissue & smooth muscle in lateral fold of the broad lig on each side.
Ovaries function and structure
Structure:
- In dorsal abdomen near kidneys.
- Appearance varies by species.
Function:
- Site of oogenesis.
- Production of estrogens & progestins.
- Ovarian cycle, ovulation, corpus luteum.
Ovarian cycle events (5) and what it’s influenced by (2)
- Influence: Follicle stim hormone & luteinizing hormone (granulosa cell produces these).
Events:
1. Primordial follicle (primary): this is an immature oocyte surrounded by single layer of follicular cells.
2. Follicular activation (growth is triggered). - Follicular cell thicken & mult. into layers: granulosa cells. Follicle grows as granulosa cells mult.
3. Granulosa cells produce increasing amounts of estrogens as follicle becomes larger.
4. Fluid-filled spaces form between granulosa cells. Spaces gradually merge into one large fluid-filled space: the antrum.
5. Mature follicle: production of estrogens peaks.
Ovulation
(sort of a cont off of ovarian cycle)
A mature follicle ruptures with the release of reproductive cell into the oviduct. Now called ovum.
- The rupture causes the release of fluid from the antrum along with ovum.
- Empty follicle fills w/blood: corpus hemorrhagicum.
Corpus Luteum formation and function
Formation:
- Granulosa cells mult. in the corpus hemorrhagicum and form a solid (corpus luteum).
- Influenced by LH continuous stim.
Function:
- Produces progestins. Necessary to maintain a pregnancy!
- Endocrine signal to ovary causes corpus L to be maintained if ovum implants in uterus.
Oviducts
AKA “fallopian tube” & “uterine tubes”
- Muscle contractions & cilia movements guide ovum toward the uterus.
- Usual site of fertilization (NOT in the uterus).
Uterus
- Hollow muscular organ.
- Y shaped: Uterine body forms the bas of the Y. Uterine horns form the arms.
- Endometrium: Lining epithelium & simple tubular glands. Secrete mucus & other substances.
Cervix
- Smooth muscle sphincter between body of the uterus and vagina.
- Normally tightly closed, except during estrus & parturition.
Vagina
Muscular tube extends caudally from the cervix & connects it with the vulva
Vulva
- Composed of vestibule, clitoris, & labia.
- Urethra opens on the floor of the vestibule.
Polyestrous
Animals that cycle continuously throughout the year if they are not pregnant
(cattle and swine)
Seasonally polyestrous
Animals with seasonal variations in estrous cycles
(cat, horse, sheep)
Diestrous
Animals with two cycles per year; usually spring and fall
(dog)
Monoestrous
Animals with one estrous cycle per year
(fox & mink)
Estrous cycle and the stages (5)
- Estrous cycle: Time from the beginning of one heat period to the next.
Stages:
1. Proestrus
2. Estrus
3. Metestrus
4. Diestrus
5. Anestrus (some species)
