CHAPTER 28: REPRODUCTIVE SYSTEM
Genotype- actual gene
Phenotype- outward expression of the gene
Barr body- found on neutrophils & inactive X chromosome
DEVELOPMENT OF THE REPRODUCTIVE SYSTEM
Gonads begin to develop from the mesodermal layer during the 5th gestational week
- Female genotype XX and male genotype XY
- In males, the Y chromosome contains the SRY gene which has a protein coding for testis
determining factor TDF
- This protein causes the primitive Sertoli cells to begin male differentiation during the 7th
gestational week
In early embryonic development, two ductal masses begin to form in the urogenital region:
1. The Wolffian ducts
2. The Mullerian ducts
- During the 7th gestational week the primitive Sertoli cells will begin the express the
Mullerian Inhibiting substance (MIS) which inhibits the growth of the Mullerian ducts
and the Wolffian ducts begin to proliferate
- They are precursors of the male reproductive system:
● Epididymis, ductus deferens, ejaculatory ducts, and seminal vesicles
- In the absence of the SRY gene the Wolffian ducts will degenerate and the Mullerian
ducts will proliferate and form the oviducts and uterus.
ABNORMAL DEVELOPMENT
1. Androgen insensitivity/ testicular feminization
- Condition that affects sexual development before birth and during puberty
- Prevents the body from using male hormones (androgens) during fetal
development
- Caused by genetic defects on the X chromosome
- Can lead to infertility
2. MRKH syndrome
- Mullerian agenesis is a congenital condition that affects individuals assigned
females at birth
- Characterized by underdeveloped vagina and uterus
- Unable to carry a pregnancy
MALE REPRODUCTIVE SYSTEM
Sperm maturation and production begins in the seminiferous tubules
- Sperm is produced here by the Sertoli cells
- Leydig cells are the site of testosterone production
, - The seminiferous tubules converge on the Rete testes before moving onto the epididymis
where they complete the process of maturation
- Sperm cells then move onto the ductus deferens which leave the scrotum & testicle and
travel into the abdomen and around the bladder
- The ductus deferens come up from the right testicle and they travel up and along the
urinary bladder
- The coccyx bone (tail bone) is on the far right side of the spine
- From the ductus deferens the first gland is the Seminal vesicle which begins the
production of sperm
● It produces fluids that buffer the acidic environment of the female reproductive
tract and fructose (nourishes sperm)
- Following the seminal vesicle is the Ejaculatory duct
● The two converge and form the common urethra
- The large gland surrounding the two is the Prostate gland
● It contributes to the formation of semen by producing a viscous alkaline fluid for
sperm to travel in
- Two round shaped organs to the right of the prostate gland at the base of the penis are the
Bulbourethral glands
● Do not contribute directly to the formation of sperm
● Produce a clear, viscous fluid alkaline in nature that is released prior to
ejaculation
● It neutralizes acids in the urinary tract left behind from urine which helps protect
sperm and acts as a lubricant
PROSTATE GLAND
- Can be an area of concern for older men
- It may become swollen and cause intermittent urine flow
- Prostate cancer is common in men over age of 50
Genotype- actual gene
Phenotype- outward expression of the gene
Barr body- found on neutrophils & inactive X chromosome
DEVELOPMENT OF THE REPRODUCTIVE SYSTEM
Gonads begin to develop from the mesodermal layer during the 5th gestational week
- Female genotype XX and male genotype XY
- In males, the Y chromosome contains the SRY gene which has a protein coding for testis
determining factor TDF
- This protein causes the primitive Sertoli cells to begin male differentiation during the 7th
gestational week
In early embryonic development, two ductal masses begin to form in the urogenital region:
1. The Wolffian ducts
2. The Mullerian ducts
- During the 7th gestational week the primitive Sertoli cells will begin the express the
Mullerian Inhibiting substance (MIS) which inhibits the growth of the Mullerian ducts
and the Wolffian ducts begin to proliferate
- They are precursors of the male reproductive system:
● Epididymis, ductus deferens, ejaculatory ducts, and seminal vesicles
- In the absence of the SRY gene the Wolffian ducts will degenerate and the Mullerian
ducts will proliferate and form the oviducts and uterus.
ABNORMAL DEVELOPMENT
1. Androgen insensitivity/ testicular feminization
- Condition that affects sexual development before birth and during puberty
- Prevents the body from using male hormones (androgens) during fetal
development
- Caused by genetic defects on the X chromosome
- Can lead to infertility
2. MRKH syndrome
- Mullerian agenesis is a congenital condition that affects individuals assigned
females at birth
- Characterized by underdeveloped vagina and uterus
- Unable to carry a pregnancy
MALE REPRODUCTIVE SYSTEM
Sperm maturation and production begins in the seminiferous tubules
- Sperm is produced here by the Sertoli cells
- Leydig cells are the site of testosterone production
, - The seminiferous tubules converge on the Rete testes before moving onto the epididymis
where they complete the process of maturation
- Sperm cells then move onto the ductus deferens which leave the scrotum & testicle and
travel into the abdomen and around the bladder
- The ductus deferens come up from the right testicle and they travel up and along the
urinary bladder
- The coccyx bone (tail bone) is on the far right side of the spine
- From the ductus deferens the first gland is the Seminal vesicle which begins the
production of sperm
● It produces fluids that buffer the acidic environment of the female reproductive
tract and fructose (nourishes sperm)
- Following the seminal vesicle is the Ejaculatory duct
● The two converge and form the common urethra
- The large gland surrounding the two is the Prostate gland
● It contributes to the formation of semen by producing a viscous alkaline fluid for
sperm to travel in
- Two round shaped organs to the right of the prostate gland at the base of the penis are the
Bulbourethral glands
● Do not contribute directly to the formation of sperm
● Produce a clear, viscous fluid alkaline in nature that is released prior to
ejaculation
● It neutralizes acids in the urinary tract left behind from urine which helps protect
sperm and acts as a lubricant
PROSTATE GLAND
- Can be an area of concern for older men
- It may become swollen and cause intermittent urine flow
- Prostate cancer is common in men over age of 50
