lecture exam 5 (ch 27 male repro)

y

male chromosome

lacking y

female chromosome

primary sex organs

• produce gametes

• testes or ovaries

male secondary sex organs

system of cuts, glands; penis delivers sperm cells

female secondary sex organs

uterine tubes, uterus, and vagina receive sperm, provide place for union of gametes, harbor developing fetus, give birth nourish offspring

secondary sex organs

organs other than gonads that are necessary for reproduction

secondary sex characteristics

features that distinguish the sexes and influence mate attraction

both sexes secondary sex characteristics

pubic and axillary hair and their associated scent glands, and the pitch of the voice

male secondary sex characteristics

facial hair, coarse and visible hair on the torso and limbs, relatively muscular physique

female secondary sex characteristics

distribution of body fat, breast enlargement, and relatively hairless appearance of the skin

23 chromosomes

• 22 pairs of autosomes

• 1 pair of sex chromosomes

sex chromosomes

• can either be x or y

  • all eggs have x

  • males produce half y half x

SRY gene

• in y chromosome

• sex determining region of y chromosome

testosterone

• testes begin to secrete at 8 to 9 weeks

• females develop due to an absence of this

• at same time, mullerian-inhibiting factor is also developing

mullerian-inhibiting factor

• in xy fetus, secreted by testes

• causes atrophy of a certain duct associated with female development

• females develop due to absence of testosterone

descent of male gonads

• initially develop high, then migrate to pelvic cavity

• beings at week 6, stimulated by testosterone

male external genitalia

• scrotum

• penis

• occupy the perinium

scrotum

• pouch of skin, muscle, and fibrous connective tissue containing the testes

internal median septum of scrotum

divides scrotum into R/L compartments

perineal raphe

• superficial median seam that overlies median septum

  • extends anteriorly along ventral side of penis and posteriorly to anus

spermatic cord

• bundle of fibrous connective tissue containing the ductus deferens (sperm duct), blood and lymphatic vessels, and

• must be held at 35 degrees C

temperature regulation of the testes

• cremaster

• dartos fascia

• pampiniform plexus

cremaster

• strips of the internal abdominal oblique muscle that enmesh the spermatic cord

  • in environmental cold temps, contracts and draws testes upward toward body; in warm temps, relaxes suspending testes further from body

dartos fascia

• subcutaneous layer containing dartos msucles

  • smooth muscle contracts when cold, wrinkling the scrotum, holding testes snugly against warm body; acts to reduce

pampiniform plexus

• extensive network of veins from testes that surround testicular artery and spermatic cord

  • functions as countercurrent heat exchanger to maintain optimum temp for sperm

  • removes heat from arterial blood, so when it reaches testis its cooler

the testes

combined endocrine and exocrine glands that produce sex hormones and sperm

• tunica albugenia

• seminiferous tubules

testes histology

• germ cells

• nurse cells

• blood-testis barrier

• interstitial endocrine cells (leyDIG)

germ cells

in process of becoming sperm

nurse cells

• protect germ cells and promote their development

• tight junctions form BLOOD-TESTIS BARRIER

blood-testis barrier

functions to separate sperm from immune system, preventing antibodies and other large molecules in the blood from getting to germ cells

interstitial endocrine cells

lie between seminiferous tubules and produce testosterone

four sperm ducts

1. efferent ductules

2. duct of epididymus

3. ductus (vas) deferens

4. ejaculatory duct

efferent ductules

about 12 small ciliated ducts collecting sperm from rete testes

duct of epididymis

• site of sperm maturation and storage

• contains a single coiled duct, adhering to posterior of testes

• sperm mature as they travel through

• sperm remain fertile 40-60 days; if they are not ejaculated, they disintegrate and are reabsorbed

ductus (vas) deferens

• muscular tube passing from scrotum through inguinal canal to posterior surface of bladder

• duct widens behind bladder into ampulla

• duct ends by uniting w seminal vesicle

• cut in vasectomy

ejaculatory duct

formed from ductus deferens and seminal vesicle; passes through the prostate to empty into prostatic urethra

three sets of accessory gland

• seminal vesicles

• prostate

• bulbourethral glands

seminal vesicles

• posterior to bladder, empties into ejaculatory duct

  • secretions form 65-75% of semen

prostate

• surrounds urethra and ejaculatory duct just inferior to bladder

  • thin milky secretion forms 25-30% of semen

bulbourethral glands

• near a dilated bulb at inner end of penis

• during sexual arousal, produce pre-ejaculate that lubricates head of penis for intercourse

• protects sperm by neutralizing acidity of urine in urethra

adolesence

period from onset of gonadotropin secretion and reproductive development to when a person attains full adult height

puberty

first few years of adolescence, until the first menstrual period in girls or the first ejaculation of viable sperm in boys

testosterone and dihydrotestosterone (DHT)

• growth of sex organs and generalized body growth

• erythropoiesis, increased basal metabolic rate, and increase in appetite

• pubic hair, axillary hair, and facial hair develop in response to DHT; associated scent and sebaceous glands develop

• stimulates sperm production and libido

lutenizing hormone

stimulates interstitial endocrine cells in testes to product testosterone

follicle stimulating hormone

stimulates nurse cells of seminiferous tubules to secrete ABP that binds/concentrates testosterone keeping testosterone in seminiferous tubule and epididymis; in this way testosterone stimulates spermatogenesis in presence of ABP

negative feedback of sperm production

• nurse cells secrete inhibin to suppress FSH

• too-high testosterone negatively feeds back to hypothalamus to reduce GnRH secretion

old man sexual function

• testosterone secretion declines with age

• decline in leydig cells

• whether andropause occurs is still being debated

  • age-related drop in testosterone and inhibin that triggers a rise in FSH and LH that could be responsible

spermatogenesis

• process of sperm production in seminiferous tubules; involves three principle events

  • division and remodeling of large germ cells into small mobile sperm with flagella

  • reduction of chromosome number (1/2)

  • shuffling of genes so each chromosome contains new gene combination

    • ensures genetic variation

mitosis

• body cells doubles its dna and then divides to produce identical daughter cells

• division of single-cell fertilized egg, growth of embryo, postnatal growth, and tissue repair

• prophase, metaphase, anaphase, telophase

meiosis

• produces four gametes (haploid cells), each with only HALF the dna of diploid body cells

  • male and female gametes

  • spermatogenesis

steps to spermatogenesis

1. spermatogonia divide by mitosis

2. primary spermatocytes → blood-testes barrier

3. (1)-spermatocytes goes thru meiosis I

4. (2)-spermatocytes goes thru meiosis II, dividing into two spermaTIDS

5. each spermatid undergoes spermiogenesis, into single spermatozoan

spermatozoan head

• nucleus - houses genetic material

• acrosome - forms thin cap over apical half; consists of lysosome to penetrate egg

• basal body - where tail attaches; assists in fertilization

spermatozoan tail

• middle piece - contains large mitochondria that produce ATP for motility

• principal piece and end piece - axoneme, which is motor apparatus for movement of sperm tail