Anatomy and Cell Biology 3309 Lecture Notes - Lecture 17: Efferent Ducts, Seminiferous Tubule, Vas Deferens
15 May 2018
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Lecture 17 – Ducts and Glands
Sperm transport and maturation
- Up to 300 lobules within the testes and each tubule is a loop like structure
o Both ends communicate with a meshwork of epithelial lined spaces
o Spermatozoa are delivered and collected in the meshwork
o Meshwork: rete testes
- Spermatozoa are collected at the apical part of the testes into several tubules called ductuli
efferentes (ducts that carry things out of the testes)
- Ductuli efferentes combine into one highly coiled tube that has elongated shape and lies
along the testes (epididymis)
o Starts in a region called the head
o Different regions have different functions
o From the head it leads to a long body and then a tail
- Single coiled tube merges and continues as a muscular epithelial lined tube (vas deferns)
- Histological image:
o Dark purple is the seminiferous tubules
o The light pink and white above it is the tubule (epididymis)
o Epididymis is enveloped in CT
- Purpose of the epididymis is to store spermatozoa for several weeks
- Spermatozoa can then leave through the vas deferens
Fluid reabsorption occurs in efferent ductules
- Dark blue image: cross section of rete testes
- Rete testes: SIMPLE CUBOIDAL EPITHELIUM *
o Forms interconnected meshwork of tubules that carry spermatozoa away from the
testes
o Carries spermatozoa into efferent ductules
- Efferent ductules: tall epithelium that is pseudostratified (tall cells and small cells)
o Carry spermatozoa into the highly coiled epididymis
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find more resources at oneclass.com
- Epididymis: epithelium is very EVEN (use this to recognize it)
o Outline is very straight
o Thickness of the epithelium is same throughout the length of the epididymis
- During journey of spermatozoa throughout the tubular system:
o Rete testes: channel that transports spermatozoa along
▪ Function: just a conductive channel
o There are complexes of testosterone and androgen binding protein (ABP)
o ABP sequesters testosterone and enriches it in the tubular fluid
▪ ABP is produced by sertoli cells under influence of FSH
o Testosterone maintains function of tubules
o Efferent ductules have an absorptive function: cell types pump NaCl out of the
lumen and create a high concentration of NaCl adjacent to the tubule
o Water will be drawn out of the tubule because of the osmotic pressure
o Spermatozoa are transported within a testicular fluid that is produced by sertoli
cells → they are immature at this stage and are unable to swim away
o Immature spermatozoa at this stage have no acquired motility yet
o Motility is acquired in the epididymis
- Starting from the epididymis into the vas deferens, more and more smooth muscle
surrounds the tubule (seen in histological section under the epididymis epithelium)
o It becomes very prominent in the vas deferens
o Function of vas deferens: deliver spermaotozoa to outside world upon stimulation
o Ejaculation involves contraction of smooth muscle that propels spermatozoa to the
outside
- Gallbladder has an epithelium that uses NaCl pumping as a means of concentrating and
removing water from lumen
find more resources at oneclass.com
find more resources at oneclass.com
Sperm transport from testis to rete testis
- As spermatozoa travels from seminiferous tubule into the rete testes, there is a significant
change in the epithelial morphology
- Morphology of seminiferous tubules:
o Spermatogenic cells are surrounded by sertoli cells
- Abruptly, seminiferous tubules open into the rete testes and spermatogenesis stops
- Only sertoli cells are left in the tubule (no spermatogenic cells anymore)
- Height of the epithelium changes to cuboidal epithelium of rete testes
- There are tight junctions that form the blood testes (at the base of the sertoli cells)
o Tight junctions move up higher as the cell height changes and they migrate to their
normal epithelial position (towards the apical end)
- Tubulus rectus: where there are all sertoli cells but no spermatogenesis
o There is a piece between the seminiferous epithelium and rete teste epithelium that
is straight
o Seminiferous tubule is coiled but here there is a straight segment that is composed
only of sertoli cells (tubulus rectus)
- PATHWAY: seminiferous tubules → tubulus rectus → rete testis
Ductuli efferentes
- From rete testis to ductuli efferentes
- IDENTIFYING FEATURE: purple pink blobs in the middle is spermatozoa
o Spermatozoa = in the male reproductive system!
- Ductuli efferentes are easily identifiable because the lumen looks saw tooth
- Pseudostratified epithelium:
o There are tall cells (ciliated) and stretches of short cells
o Basal cells (stem cells) do not reach the surface
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Up to 300 lobules within the testes and each tubule is a loop like structure: both ends communicate with a meshwork of epithelial lined spaces, spermatozoa are delivered and collected in the meshwork, meshwork: rete testes. Spermatozoa are collected at the apical part of the testes into several tubules called ductuli efferentes (ducts that carry things out of the testes) Single coiled tube merges and continues as a muscular epithelial lined tube (vas deferns) Histological image: dark purple is the seminiferous tubules, the light pink and white above it is the tubule (epididymis, epididymis is enveloped in ct. Purpose of the epididymis is to store spermatozoa for several weeks. Spermatozoa can then leave through the vas deferens. Dark blue image: cross section of rete testes. Rete testes: simple cuboidal epithelium : forms interconnected meshwork of tubules that carry spermatozoa away from the testes, carries spermatozoa into efferent ductules.
