Lecture 1: female and male reproductive systems Flashcards
somatic cells
contain 46 chromosomes
- 1 copy from mom
- 1 copy from dad
meiosis
- 2 nuclear division
- restricted to gametogenesis
gametogenesis
the development of the male and female gamete (sperm and oocyte)
gamete
mature haploid male or female germ cell that is able to combine with another of the opposite sex to produce a gamete
first meiotic division
- replication of DNA
- synapsis (unique)
- cross over (unique)
- disjunction (unique)
results in: 2 daughter cells with half the chromosomes
and 2 sets of DNA
synapsis
exact pairing of homologous chromosomes (identical portions on each chromosomes match up)
crossing over
exchange of chromatid segments between the paired homologous chromosomes
disjunction
homologous pairs separate (not sister chromatids)
second meiotic division
- NO DNA replication
- resembles mitosis (sister chromatids separate)
results: four daughter cells with half the number of chromosomes and half the normal amount of DNA – with a recombination of genetic material.
Meiosis and numerical chromosomal abnormalities
30-50% of conceptions end in spontaneous abortions and that 50% of these spontaneous abortions have major chromosomal abnormities
usually result from nondysjunction
trisomy
extra chromosome when sperm and egg unite (21,18,13)
associated with first meiotic division
monosomy
chromosome is missing when egg and sperm unite
associated with second meiotic division
nondisjunction
error in cell division
- failure of chromosomal pair OR two chromatids to disjoin
- may occur in maternal or paternal gametogenesis
trisomy 21
- broad face with flat bridge nose and wide set eyes
- hands are broad and have the characteristic transverse single palmer crease
- hypotonia, heart defects and early onset of Alzheimers’s disease
organs of the female reproductive system
- ovaries
- oviduct (uterine tube, fallopian tube)
- uterus and cervix
- vagina
2 functions of ovaries
- oogenesis (exocrine) production of gametes
- steroidogenesis production of hormones (endocrine)
2 major events that occur in the ovaries
- maturation of the oocyte
- maturation of the ovarian follicle
maturation of the oocyte
- gametes are derived from primordial germ cells (PGC) formed in yolk sac of the developing female embryo- these cells migrate to developing ovary and differentiate into oogonia
- oogonia undergo mitosis- at 5 months post fertilization there are millions oogonia
- eventually they differentiate into primary oocytes and lose the ability to undergo mitosis
primary oocytes
- become surrounded by connective tissue cells (follicular cells) of the ovary forming the primordial follicle (first in a sequence of follicles
- begin the first meiotic division but the division is halted in prophase (of meiosis I).
- remains arrested until at least adolescence- possibly until the fifth decade of the females life (menopause)
maturation of ovarian follicle
- primordial follicles begin to mature at puberty-under the influence of hormones
- some of the follicles will be “chosen” each month to grow–> only one (normally) will be ovulated each month
four types of follicles
- primordial follicle
- primary follicle
- secondary follicle (atral)
- mature, Graffian, preovulatory follicle
primordial follicle
follicular cells surround the oocyte that is arrested in prophase 1
primary follicle
- onset of puberty: the follicular cells become cuboidal and are now called granulosa cells
- zona pellucida forms and is important in the fertilization process
secondary follicle (atral)
intercellular spaces fill with fluid, a large, single fluid filled antrum is formed
mature, Graffian, preovulatory follicle
the oocyte is surrounded zona pellucida and some granulosa cells called the corona radiata
day 14 of the menstrual cycle
ovulation occurs
the largest, most mature follicle contains the oocyte that will be ovulated
coprous luteum
forms from the follicle once the mature oocyte, zona pellucida, and corona radiata are released and it produces hormones to maintain pregnancy until placenta takes over
what occurs with hormonal surge 36 hours prior to ovulation?
- completion of first meiotic division-result is a polar body and the secondary oocyte
- will begin meiosis II which is again halted ( the female oocyte will only complete meiosis II if fertilized by the sperm)
ovulation occurs when:
secondary oocyte, zona pellucida, and corona radiata are released from the mature follicle into the peritoneal cavity
corpus luteum
- forms from the follicle (remaining granulosa cells) once the mature oocyte, zona pellucida, and corona radiata are released
- it produces hormones that target the endometrium to maintain pregnancy until placenta takes over
corpus luteum becomes either:
- corpus luteum of pregnancy
- corpus luteum of menstruation
corpus albicans
fibrous tissue that is reabsorbed over a period of several months
-formed from the corpus luteum of menstruation if pregnancy does not take place
uterine tube
transport ovum to uterus and nourish zygote
parts of the uterine tube
- infundibulum with fimbriae: not attached to the ovary
- ampulla: where fertilization takes place
- isthmus
- intramural
mucosal lining of the uterine tube
simple columnar epithelium
2 cell types in the uterine tube
- ciliated cells
- non ciliated peg cells
ciliated cells
must numerous in the infundibulum and ampulla- beat toward the uterus
non ciliated peg cells
secretory cells that produce the fluid that provides nutritive material for the ovum (fertilized egg)
2 functions for transport of oocyte to the uterus
- ciliated cells
- muscularis layer of the oviduct
uterus
hallow shaped organ that receives zygote, site of embryonic and fetal development
3 layers of the uterus
- endometrium
- myometrium: smooth muscle layer
- perimetrium: serosal layer covering most of the uterus (mesothelium and CT)
2 layers of the endometrium
- stratum functionale (functional layer- sloughed off at menstration)
- stratum basale (basal layer- retained during menstration, regenerates the functional layer)
during the menstrual phases the endometrium:
- varies in thickness
- surface epithelium invaginate to form glands
- arteries form a rich capillary bed
cervix
- part of, but different than body of uterus
- endometrium does not change during the menstrual cycle, contains mucous producing glands.
- during the birthing process, the cervix dilates and softens
vagina
- joins reproductive organs with external environment
- fibromuscular tube that allows transport of sperm to the uterus, flexibility during the birthing process
3 phases of the menstrual cycle
- menstrual phase
- proliferative phase
- secretory phase
menstrual phase
-day 1-4, the functional layer is sloughed off
proliferative phase
-day 5-14, the functional layer becomes thicker
secretory phase
-day 15- 28, the functional layer is very thick, the glands are filled with glycogen
testis
- paired organs located in scrotum
- initial development in the abdominal cavity, descend with layers of the wall to the scrotum
- endocrine (production of testosterone by Lehdig cells) and exocrine (production of sperm) organs
- surrounded by thick connective tissue capsule that extends into each testis to divide it to lobules
- each lobules contain seminiferous tubules, in which sperm are produced
seminiferous tubules
- lined with cells that develop into sperm in a process called spermatogenesis
- stem cells divide to produce more sperm
- extensive remodeling occurs to become morphologically mature
spermatogenesis lasts approximately
74 days
duct system
- duct recti
- rete testis
- efferent ductules
- epididymis
- ductus (vas) deference
- ampulla
- ejaculatory duct
duct recti
-found at the end of each seminiferous tubules
rete testis
where the duct recti empties sperm in
efferent ductules
connectretetestisto the epididymis
epididymis
where sperm acquire motility and where they “gain ability” to fertilize the egg
ductus (vas) deference
this is the longest part and extends into the pelvis where it enlarges to form the ampulla
ampulla
merges with the duct of the seminal vesicle (accessory gland) to form the ejaculatory duct
ejaculatory duct
enter the prostate gland- the single urethra will now carry the sperm to the external environment (also carries urine)
seminal vesicles
secrete a fluid rich in fructose
prostate gland
(largest accessory sex gland) secretes several enzymes
