ANAT 7390 Lecture Notes - Lecture 1: Tunica Vaginalis, Seminiferous Tubule, Rete Testis
17 Jun 2018
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TOPIC XVII: REPRODUCTIVE SYSTEMS
A) Structures: Overview
- gonads (testes/ovaries)
- produce gametes + hormones
- ducts
- transport & store gametes
- accessory glands
- produce secretions that support gametes
B) Male Reproductive System Structures
1) gonads = testes
- located within the scrotum (skin + CT)
- surrounded by 2 tunics:
a) tunica vaginalis
- outer serous membrane
- derived from peritoneum
b) tunica albuginea
- inner fibrous capsule of CT
- extends inward to divide testis into lobules
- each lobule contains:
a) seminiferous tubules
- produce sperm by spermatogenesis
- tubules unite to form rete testis (rete = network)
- walls contain:
i) germ cells in various stages of development
ii) Sertoli cells (sustentocytes)
- surround developing gametes
- extend from basement membrane to lumen
- support and nourish germ cells
- have tight junctions - form blood-testis barrier
- protects sperm from immune system,
toxins, drugs etc
- produce testicular fluid
- for transport of sperm in lumen
- respond to follicle-stimulating hormone (FSH)
b) Leydig cells (interstitial cells)
- in CT between seminiferous tubules
- secrete testosterone (hormone)
2
2) Ducts:
Ducts
- sperm from seminiferous tubules into rete testis
- then into duct system:
a) Epididymis
- posterior border of testis
- stores sperm
- sperm mature (develop ability to swim)
b) Vas (ductus) deferens
- enters pelvic cavity
- loops over posterior bladder
- vasectomy = vas deferens cut & tied off
- Spermatic Cord - contains vas deferens, nerves (ANS) veins,
artery, lymph vessels, muscle (skeletal)
c) Ejaculatory Duct
- formed by union of vas deferens and duct from seminal vesicle
d) Urethra
- 3 regions:
i) prostatic - through prostate
ii) membranous - through urogenital diaphragm
iii)) penile (spongy) - through corpus spongiosum of penis
- opens on the glans penis
3) Penis
- parts:
a) root
b) body (shaft)
c) glans penis (enlarged tip)
- 3 bodies of erectile tissue - contains blood sinuses, bound by CT
→ 2 corpora cavernosa (dorsal portion of root and shaft)
→ 1 corpus spongiosum (the glans and the midventral portion of the root
and shaft, surrounding the urethra)
4) Accessory Glands
~ 95% of semen
a) Seminal vesicles (2)
- posterior to bladder
- secrete alkaline fluid that contains fructose to nourish sperm
~ 60% of volume of semen
b) Prostate Gland (1)
- inferior to bladder and encircles prostatic urethra
3
- secretes milky, alkaline fluid - nourishes sperm
~ 30% of volume of semen
c) Bulbourethral glands (2)
- below prostate in urogenital diaphragm (in contact with external
urethral sphincter)
- secrete thick alkaline mucus – helps neutralize acidic urine in
urethra, lubricates
~ 5% of volume of semen
C) Male - Spermatogenesis
- sperm production (within seminiferous tubules)
Spermatogonia (2n)
↙ ↘
↙ mitosis ↘
↙ ↘
differentiate ↙ ↘
1 1⁰ spermatocyte (2n) spermatogonia (2n)
↓ meiosis I maintains cell line
↓
2 2⁰ spermatocytes (n)
↓ meiosis II
↓
4 spermatids (n)
↓ Spermiogenesis (final stage)
↓
4 spermatozoa (n)
- differentiation of a spermatid = spermiogenesis:
- develop acrosome + flagellum
- lose most cytoplasm
- spermatozoon structure:
1) Head
- nucleus (23 chromosomes (n))
- at tip of nucleus = acrosome
- contains digestive enzymes (to penetrate oocyte)
2) Body (midpiece)
- large # mitochondria
- produce ATP for movement
3) Tail = flagellum
Document Summary
Topic xvii: reproductive systems: structures: overview, male reproductive system structures. Located within the scrotum (skin + ct) Surrounded by 2 tunics: tunica vaginalis, tunica albuginea. Extends inward to divide testis into lobules: seminiferous tubules. Tubules unite to form rete testis (rete = network) Walls contain: germ cells in various stages of development, sertoli cells (sustentocytes) Have tight junctions - form blood-testis barrier. For transport of sperm in lumen toxins, drugs etc: leydig cells (interstitial cells) Sperm from seminiferous tubules into rete testis. Then into duct system: epididymis, vas (ductus) deferens, ejaculatory duct, urethra. Vasectomy = vas deferens cut & tied off. Spermatic cord - contains vas deferens, nerves (ans) veins, artery, lymph vessels, muscle (skeletal) Formed by union of vas deferens and duct from seminal vesicle: prostatic - through prostate, membranous - through urogenital diaphragm iii)) penile (spongy) - through corpus spongiosum of penis, penis, root, body (shaft, glans penis (enlarged tip)
