Human Development
Exam One
, Lecture 2A – week 1
Male reproduction
Reproductive system
- Gonads (organs that product gametes and hormones)
- Ducts (receive and transport gametes)
- Accessory glands (secrete fluids into ducts)
- Perineal structures (external genitalia)
Sex
- Genetic sex (chromosomes)
- Gonadal sex (gonads)
- Genitals (internal and external, in utero development)
Gender
- Social meaning attached to being male/female
- Sexual/gender identity (one’s identity as male/female/other)
- Gender role (expectations, develops in utero throughout childhood)
MALE REPRODUCTIVE SYSTEM – Brain and hormones
Hypothalamus GnRH
Pituitary gland ACTH adrenal glands produce testosterone
FSH, L
H testes produce testosterone
Testes testosterone
Reproductive glands 5-alpha reductase > DHT/AR
T/AR
MALE REPRODUCTIVE SYSTEM – Organs
Gonads testes (reproductive organs)
Ducts vas deferens
Accessory glands seminal vesicles
bulbourethral gland (Cowper’s gland)
prostate gland
Perineal structures scrotal sac
penis
,Spermatozoa pathway
➔ Testis
➔ Epididymis
➔ Ductus deferens
➔ Ejaculatory duct (fluids are secreted by the seminal vesicles, prostate, Cowper’s gland)
Spermatozoa development requires a temperature that is 1.1˚C lower than the normal
body temperature. This takes place ‘outside’ the body in the testes. The cremaster and
dartos muscles relax and contract (the scrotum) to regulate the temperature of the testes.
Inguinal canals are passageways through the abdominal musculature for the descent of
the testes and are closed later in life (males risk an inguinal hernia).
Seminiferous tubules (in the testes) = spermatozoa production, travels from the rete testis
to the respective epididymis. The tubules are divided by septa, by which they are
compartmentalized.
Seminiferous tubules
- Contain spermatogonia
• Stem cells involved in spermatogonia
• Production of spermatozoa
- Contain sustentacular cells (Sertoli cells)
• Sustain development of sperm
• Promote development of sperm
Interstitial cells (Leydig cells, more within the septa)
Germ cells divide by meiosis
- Male primordial germ cells = spermatogonia (stem cells)
- Type A continually duplicating via mitosis throughout a male’s reproductive life
self renewal, symmetric division (remains)
- Type B development into sperm cells via meiosis
different fates, asymmetric division (becomes primary spermatocyte)
- Product = not identical to one another and to the parent cell
- Spermatogonia > spermatozoa
- Recombination occurs during late prophase, creating four different copies of each
chromosome every time meiosis occurs (function: increase of genetic variation)
* number of different gametes = 2n (human: 8.5 million possibilities)
, SPERMATOGENESIS
Development from outside to inside (lumen) of the cell
- Spermatogonia, one of which proceeds to mitosis, diploid
- Primary spermatocytes DNA replication, tetrad
- Secondary spermatocytes meiosis I
- Spermatids meiosis II, haploid
- Spermatozoa spermiogenesis, haploid
• Lose contact with seminiferous tubule wall
• Enter fluid in lumen
* spermiogenesis = physical maturation (five weeks)
* gametes = germ cells = sex cells (haploid)
* development is along sustentacular (Sertoli) cells
* cytodifferentiation = development of specialized cells from unspecialized ones through
the stimulation of specific nutritional and hormonal factors
Spermiogenesis = last step of spermatogenesis in which each spermatids matures into
one spermatozoon (sperm cell). The spermatids shed cytoplasm, which is phagocytized by
Exam One
, Lecture 2A – week 1
Male reproduction
Reproductive system
- Gonads (organs that product gametes and hormones)
- Ducts (receive and transport gametes)
- Accessory glands (secrete fluids into ducts)
- Perineal structures (external genitalia)
Sex
- Genetic sex (chromosomes)
- Gonadal sex (gonads)
- Genitals (internal and external, in utero development)
Gender
- Social meaning attached to being male/female
- Sexual/gender identity (one’s identity as male/female/other)
- Gender role (expectations, develops in utero throughout childhood)
MALE REPRODUCTIVE SYSTEM – Brain and hormones
Hypothalamus GnRH
Pituitary gland ACTH adrenal glands produce testosterone
FSH, L
H testes produce testosterone
Testes testosterone
Reproductive glands 5-alpha reductase > DHT/AR
T/AR
MALE REPRODUCTIVE SYSTEM – Organs
Gonads testes (reproductive organs)
Ducts vas deferens
Accessory glands seminal vesicles
bulbourethral gland (Cowper’s gland)
prostate gland
Perineal structures scrotal sac
penis
,Spermatozoa pathway
➔ Testis
➔ Epididymis
➔ Ductus deferens
➔ Ejaculatory duct (fluids are secreted by the seminal vesicles, prostate, Cowper’s gland)
Spermatozoa development requires a temperature that is 1.1˚C lower than the normal
body temperature. This takes place ‘outside’ the body in the testes. The cremaster and
dartos muscles relax and contract (the scrotum) to regulate the temperature of the testes.
Inguinal canals are passageways through the abdominal musculature for the descent of
the testes and are closed later in life (males risk an inguinal hernia).
Seminiferous tubules (in the testes) = spermatozoa production, travels from the rete testis
to the respective epididymis. The tubules are divided by septa, by which they are
compartmentalized.
Seminiferous tubules
- Contain spermatogonia
• Stem cells involved in spermatogonia
• Production of spermatozoa
- Contain sustentacular cells (Sertoli cells)
• Sustain development of sperm
• Promote development of sperm
Interstitial cells (Leydig cells, more within the septa)
Germ cells divide by meiosis
- Male primordial germ cells = spermatogonia (stem cells)
- Type A continually duplicating via mitosis throughout a male’s reproductive life
self renewal, symmetric division (remains)
- Type B development into sperm cells via meiosis
different fates, asymmetric division (becomes primary spermatocyte)
- Product = not identical to one another and to the parent cell
- Spermatogonia > spermatozoa
- Recombination occurs during late prophase, creating four different copies of each
chromosome every time meiosis occurs (function: increase of genetic variation)
* number of different gametes = 2n (human: 8.5 million possibilities)
, SPERMATOGENESIS
Development from outside to inside (lumen) of the cell
- Spermatogonia, one of which proceeds to mitosis, diploid
- Primary spermatocytes DNA replication, tetrad
- Secondary spermatocytes meiosis I
- Spermatids meiosis II, haploid
- Spermatozoa spermiogenesis, haploid
• Lose contact with seminiferous tubule wall
• Enter fluid in lumen
* spermiogenesis = physical maturation (five weeks)
* gametes = germ cells = sex cells (haploid)
* development is along sustentacular (Sertoli) cells
* cytodifferentiation = development of specialized cells from unspecialized ones through
the stimulation of specific nutritional and hormonal factors
Spermiogenesis = last step of spermatogenesis in which each spermatids matures into
one spermatozoon (sperm cell). The spermatids shed cytoplasm, which is phagocytized by
