BSC2086L Lesson 10

testes

male reproductive organ

ovaries

female reproductive organ

gonads produce:

sex cells and hormones

males produce:

sperm and testosterone

females produce:

ova (eggs) and estrogen (both in follicles) and progesterone

penis

composed of 3 cylinders of erectile tissue, 2 dorsal cylinders (corpora cavernosa) and 1 ventral cylinder (corpus spongiosum) which surrounds penile urethra

glans penis

tip of penis covered by prepuce/foreskin

shaft

body of penis

scrotum

contains the testes; regulates temperature to optimize sperm production (94ºF/34ºC)

duct system

accessory structures that form the ducts that carries sperm from testes to external environment

epididymis

located on the superior and posterolateral area of the testes; site where immature sperm cells complete maturation process

ductus deferens/vas deferens (sperm duct)

along with blood vessels and nerves, they are enclosed in connective tissue sheath called spermatic cord; connects the epididymis to ejaculatory duct to ampulla

ejaculatory duct

propels sperm through prostate gland to urethra during ejaculation

urethra (male)

runs the length of penis, common path of both the urinary and reproductive system; has 3 parts (prostatic, intermediate part (membranous), and spongy)

accessory glands

produces seminal fluid that bathes sperm; includes prostate gland, seminal glands/vesicles, and bulbourethral glands

prostate gland

inferior to bladder, encircles and secretes milky fluid into urethra to activate sperm

seminal glands/vesicles

posterior to bladder, joins ductus deferens to form ejaculatory duct; produces alkaline secretion containing fructose and other nutrients which supplies energy to sperm cells or promotes fertilization; produces 60% of seminal fluid

bulbourethral glands

inferior to prostate; produces thick, clear, alkaline mucus that drains into membraneous urethra (washes out urine during ejaculation and of semen (sperm and seminal fluid))

structure of testes

covered by tunica albuginea (dense connective tissue), extends into interior (forms many septa) to divide testis into lobules

seminiferous tubules

site of sperm production; interstitial cells between tubules produce testosterone

rete testis

carries sperm from seminiferous tubules to epididymis

external structures of female reproductive system

external genitalia (vulva) and mammary glands

mons pubis

overlies pubic symphysis

labia majora

homologous to scrotum in males

labia minora

enclose vestibule region

clitoris

homologous to penis in males, covered by prepuce of the clitoris

urethral orifice

part of the urinary system, separate from the reproductive system

vaginal orifice

external opening that leads into the internal reproductive structures

hymen

thin fold of mucous membrane, closed vaginal opening

greater vestibular glands

flanks vaginal opening, produces lubricants during coitus

all organs except ovaries are suspended by:

ligamentous folds of peritoneum

broad ligaments:

?? secures uterus

?? secures uterine tubes

?? anchors ovaries posteriorly

broad ligaments:

mesometrium

mesosalpinx

mesovarium

round ligaments

secures uterus to labia majora

uterosacral ligaments

secures inferior uterus to the sacrum

ovarian ligament

anchors ovaries to uterus

suspensory ligaments

anchors ovaries laterally

vagina

birth canal connecting vestibule to uterus

uterus

muscular organ located between bladder and rectum

endometrium

interior layer of uterine wall, composed of a functional layer (stratum functionalis) that is formed by basal layer/stratum basalis

stratum functionalis

functional layer of endometrium that is the usual site of egg implantation and is discarded during menses

myometrium

muscular medial layer of uterine wall

serosa

protective outer layer of uterine wall

major structures of uterus:

?? inferior uterus

?? major portion of uterus

?? superior uterus

major structures of uterus:

cervix

body

fundus

uterine/fallopian tubes

located at superolateral region of uterus extending toward ovaries; usual site of egg fertilization by sperm

fimbriae

finger or fringe like projections at the distal end of uterine/fallopian tubes, closest to ovaries

ampulla

widest, longest portion of uterine/fallopian tubes

isthmus

located medially and is narrow with thick-walled of uterine/fallopian tubes

ovulation

egg ejection (follicle forms corpus luteum to produce progesterone and some estrogen)

mammary glands

located anterior to pectoral muscles; growth starts in puberty, caused by estrogen production; major features

aerola

pigmented area surrounding nipple

nipple

site of milk release in lactation

lobes of mammary glands

15-25 lobes composed of connective and fatty tissue; contain lobules containing milk producing alveoli (milk formed here passes through lactiferous ducts and stored in lactiferous sinus)

haploid complement (n)

1/2 normal chromosome number (2n); has 23 chromosomes

fusion of sperm (n) and egg (n)

restores the 23 pairs of chromosomes (2n)

fertilized egg has

23 chromosome pairs/is diploid

mitosis

occurs in somatic cells; chromosome number is conserved: the daughter cells have the same number of chromosomes as the parent cell (2n - diploid)

meiosis

consists of 2 nuclear divisions: I and II; end yields 4 daughter cells

meiosis I

- chromosomes undergo semi-conservative replication; occurs ininterphase (before meiosis occurs)

- in the process of synapsis, homologous chromosomes (containing genes for the same trait) line up side to side to form pairs called tetrads

- 23 tetrads line up at equator and the homologous chromosomes can exchange genetic material with its pair at points of crossover/chiasmata

- after the crossover event, the dyads move to opposite ends during anaphase

- cytokinesis occurs to yield 2 daughter cells after telophase

meiosis II

- genetic material does not replicate in meiosis II; each daughter cell of meiosis I has only ½ the homologous chromosomes

- each daughter cell forms 2 daughter cells (so the two daughter cells from meiosis I each produces two daughter cells to yield a total of 4 daughter cells by the end of meiosis II)

spermatogenesis

starts at puberty; occurs in seminiferous tubules of testes from spermatogonia (primary stem cells)

spermatogonia

under FSH influence during puberty, produces primary spermatocytes (through mitosis), which then undergo meiosis to yield spermatids (these undergo spermiogenesis to form functional sperm)

oogenesis

occurs in ovary (ovum encased in follicle by follicle/granulosa cells); influenced by gonadotropic hormones from anterior pituitary; begins with oogonia (primary stem cells) in developing female fetus (does not begin in puberty)

oogonia

undergoes thousands of mitotic divisions in fetal development; become encapsulated by cells to form primordial follicles of ovaries

primary oocytes

by birth, encapsulated oogonia grows into primary oocyte (arrested at prophase of meiosis I)

at puberty, FSH causes:

one/more follicle maturation

primary follicle

formed as follicle grows around primary oocyte follicle cells produces estrogens

secondary follicle

primary oocyte maturing; estrogen produced feedback to stop gonadotropin release by anterior pituitary

vesticular (antral) follicle

primary oocyte completes meiosis I producing secondary oocyte (arrested at metaphase II) and first polar body

the mature follicle releases secondary oocyte enclosed corona radiata (formed by granulosa cells) when anterior pituitary suddenly increases LH release; turns into corpus luteum (produces progesterone & estrogen)

if LH levels drop, the corpus luteum:

degenerates and replaced by scar tissue (corpus albicans)

upon sperm fertilization of the secondary oocyte:

meiosis II proceeds and ovum (2n) and second polar body produced

menstrual cycle

controlled by ovary (estrogen/progesterone); occurs 14 days after ovulation; divided into 3 phases

menstrual (menses)

day 1-5 where functional layer of endometrium sloughs off/bleeding occurs

proliferative

day 6-14 where estrogen from growing follicle causes endometrium repair, glands & blood vessels proliferate, & endometrium thicken

secretory

day 15-28 where corpus luteum progesterone causes increase glands & vascular supply in endometrium; if embryo present, embryo will produce LH to maintain corpus luteum