Male Reproductive Histology (Dennis) Flashcards
1
Q
What are the main functions of the male reproductive system?
A
- production, nourishment, and temporary storage of sperm
- synthesis/secretion of male sex hormones (androgens)
2
Q
Where does sperm and androgen production occur?
A
testes
3
Q
What structures transport sperm?
A
- epididymis
- ductus deferens
- ejaculatory duct
- urethra
4
Q
What structures help produce semen?
A
- seminal vesicles
- prostate gland
- bulbourethral gland
5
Q
What are the structures a/w the testes?
A
- testes: paired organs located in the scrotum, posteriorly a/w the epididymis
- tunica albuginea (TA): dense CT capsule
- TA forms the mediastinum testis (posterior), network of fibrous CT that extends from top to near bottom of each testis
- septa create lobules in which seminiferous tubules are housed
- tunica vaginalis: derived from peritoneum, has an outer parietal layer lining the scrotum and an inner visceral layer covering the tunica albuginea
6
Q
What structures are a/w the seminiferous tubules?
A
- septa create 250-300 lobules containing 1-4 convoluted seminiferous tubules lined w/ seminiferous epithelium composed of:
1. sustentacular (Sertoli) cells
2. spermatogenic cells - tubules surrounded by CT and 3-5 layers of flattened, peritubular myoid cells (create peristaltic contractions that help move spermatozoa)
- interstitial cells of Leydig found in between seminiferous tubules
7
Q
Identify the structures in the following images:
A
- IC: interstitial cells
- SC: Sertoli cells
- M: peritubular myoid cells
- F: fibroblasts
- SG: spermatogonia
- PS: primary spermatocytes
- ES: early spermatids
- LS: late spermatids
8
Q
- steroid-producing cells (testosterone) containing lipid droplets, mito, and well-developed sER
- present in between tubules, close to blood vessels and lymphatic channels
- accompanied by myoid cells and fibroblasts
A
interstitial cells (of Leydig)
9
Q
Identify the structures in the following images:
A
- BV: blood vessel
- L: lobule
- LC: leydig cells
- LP: lamina propria
- S: CT septa
- Sc: spermatocytes
- Sg: spermatogonia
- Sn: Sertoli nucleus
- Sp: spermatids
- TA: tunica albuginea
- X: tangential section of tubule w/ lumen obscured
- arrows: spermatid nuclei displaying early shape change
10
Q
What are the structures/cells a/w seminiferous epithelium?
A
- SE: stratified epithelium w/ unusual characteristics
- sustentacular (Sertoli) cells: columnar cells w/ extensive processes that surround spermatogenic cells and occupy spaces between them; organize tubules and extend through the full thickness of epithelium; hallmark is cyclops nucleus
- spermatogenic cells: replicate and differentiate into mature sperm; spermatogonia (most immature) rest on basal lamina; spermatids (most mature) are attached to apical portion of Sertoli cell near tubule lumen
11
Q
- “nurse” cells w/ crypts supporting 30-50 germ cells
- function in: exchange/transport of metabolites and nutritive factors into lumen; exocrine/endocrine secretion; phagocytose residual bodies (spermiogenesis) and effete spermatogenic cells
- bound by tight junctions to form Sertoli cell-to-Sertoli cell junctional complex: creates 50+ parallel lines of fusion along basolateral membranes, establishes blood-testis-barrier
A
Sertoli cells
12
Q
What are the different types of spermatogenic cells?
A
- spermatogonia: clonoally divide (mitosis), located near basement membrane; type A spermatogonia (generates copies of itself and/or differentiates into type B); type B spermatogonia (enter meiotic prophase as primary spermatocytes)
- spermatocytes: two meiotic divisions and inside blood-testes barrier; primary spermatocytes > secondary spermatocytes > spermatids
13
Q
How is a blood-testis barrier established?
A
- Sertoli-Sertoli junctional complex divides epithelium into basal and luminal compartments
- complexes establish blood-testis barrier: isolates haploid germ cells (secondary spermatocytes, spermatids, and sperm) from systemic circulation
14
Q
How do pre-sperm cells move through the seminiferous compartments?
A
- spermatogonia and early primary spermatocytes are restricted to basal compartment
- primary spermatocytes pass through junctional complex, move from basal > luminal compartment
- mature spermatocytes and spermatids are restricted to luminal compartment
15
Q
How do spermatids mature and where are they housed during their stages?
A
- spermatids undrego spermiogenesis and differentiate into mature sperm cells
- round (early) sperm: housed in niches of Sertoli cells
- elongated (late) spermatids: housed in apical crypts of Sertoli cells
16
Q
- the release of mature spermatids into lumen
- spermatids lose intercellular bridges and mature spermatids are separated
- spermatozoa are fully formed, but not yet functional
- sperm are propelled into epididymal duct
A
spermiation
17
Q
What is the general structure of sperm?
A
- comprised of head, neck, and tail
- head: contains flattened, elongated nucleus; partially capped by acrosome; contains hydrolytic enzymes
- tail: subdivided into middle piece containing mitochondria, principal piece which is the longest segment, and end piece
18
Q
What is the pathway for sperm transport>
A
straight tubules
>
rete testis
>
efferent ductules
>
epididymis
>
ductus deferens
>
ejaculatory duct
19
Q
Seminiferous tubules
- location:
- epithelium:
- support tissues:
- functions:
A
Seminiferous tubules
- location: testicular lobules
- epithelium: spermatogenic w/ Sertoli and germ cells
- support tissues: myoid cells and loose CT
- functions: produce sperm
20
Q
Straight tubules
- location:
- epithelium:
- support tissues:
- functions:
A
Straight tubules
- location: periphery of the mediastinum testis
- epithelium: proximal = Sertoli cells only; distal = simple cuboidal
- support tissues: connective tissue
- functions: convey sperm into rete testis
21
Q
Rete testis
- location:
- epithelium:
- support tissues:
- functions:
A
Rete testis
- location: in mediastinum testis
- epithelium: simple cuboidal w/ microvilla and single cilia
- support tissues: dense irregular CT, highly vascular
- functions: collects sperm from seminiferous tubules
22
Q
Efferent ductules
- location:
- epithelium:
- support tissues:
- functions:
A
Efferent ductules
- location: from rete testis to head of epididymis
- epithelium: alternating patches of simple cuboidal nonciliated and simple columnar ciliated
- support tissues: thin circular layer of smooth muscle and vascular loose CT
- functions: convey sperm into the epididymis
23
Q
Epididymal duct
- location:
- epithelium:
- support tissues:
- functions:
A
Epididymal duct
- location: head, body, tail of epididymis
- epithelium: pseudostratified columnar w/ stereocilia
- support tissues: circular smooth muscle initially, w/ inner and outer longitudinal layers in tail
- functions: sperm maturation and short-term storage, expels sperm at ejaculation
24
Q
Ducutus deferens
- location:
- epithelium:
- support tissues:
- functions:
A
Ducutus deferens
- location: extends from epididymis to ejaculatory ducts in prostate gland
- epithelium: pseudostratified columnar w/ fewer stereocilia
- support tissues: fibroelastic lamina propria, inner longitudinal + middle circular + outer longitudinal layers of smooth muscle
- functions: carries sperm from epididymis > ejaculatory duct
25
Ejaculatory ducts
- location:
- epithelium:
- support tissues:
- functions:
**Ejaculatory ducts**
- location: ductus deferens + ducts of seminal vesicles, located in prostate
- epithelium: pseudostratified and simple columnar
- support tissues: fibroelastic tissue + smooth muscle
- functions: mix sperm and seminal fluid, deliver semen to urethra, prostatic secretion is added here
26
What structures are a/w the epididymis?
- **epididymis**: highly elongated and coiled duct (about 6 m) where sperm mature, has a **head, body,** and **tail**
- composed of **psuedostratified columnar** epithelium w/ long **stereocilia**: 1) **principal cells**: columnar cells extending from lumen to basal lamina w/ stereocilia, 2) **stem cells** of principal cells
- has a thin circular layer of smooth muscle cells; in tail region there is an addition of inner and outer longitudinal layers
- sperm maturation consists in acquiring **forward motility**, mature sperm are stored in tail
27
Identify the structures in the following image:
- AT: adipose tissue
- BV: blood vessel
- C: cilia
- CT: connective tissue
- P: pigment
- SC: stereocilia
- SM: smooth muscle
- arrows: islands of epithelium in the lumen
28
What structures are a/w ductus deferens?
- **ductus deferens**: 45 cm muscular tube lined w/ **pseudostratified columnar epithelia w/ sparse stereocilia**, supported by a CT lamina propria w/ elastic fibers
- muscular wall: **inner** and **outer longitudinal layers**, and **middle circle layer**
- external layer consists of loose CT and adipocytes
- **ampulla**: dilated portion that leads directly into prostate gland
- distal ends receive ducts of seminal vesicle, forming **ejaculatory ducts**
29
Identify the structures in the following images:
30
What are the accessory glands of the male reproductive system?
- seminal vesicles (2), prostate gland (1), bulbourethral glands (2), urethral glands
- seminal vesicles and prostate gland prod majority of seminal fluid, function is regulated by androgens (testosterone and DHT)
- - all glands empty into the **prostatic urethra** \> end site of prostatic ducts (prostatic secretions) and ejaculatory ducts (semen and secretions from seminal vesicles)
31
What is the function and histological structure of seminal vesicles?
- function: prod alkaline secretion rich in fructose and prostaglandins, contributes to semen (~70%), excretory duct penetrates the prostate after joining ductus deferens \> from ejaculatory duct
- histology: external CT capsule, highly folded mucosa lined by **pseudostratified columnar epithelium**, inner circular and outer longitudinal smooth muscle
32
Identify the structures in the following image and where in the body this sample was obtained:
seminal vesicles
33
What are the zones of the prostate gland?
(prostate: collection of 30-50 tubuloacinar glands embedded in dense fibromuscular stroma, CT capsule)
- **central zone**: surrounds ejaculatory ducts as they pierce prostate gland (~25% of glandular tissue)
- **peripheral zone**: surrounds central zone and posteriolateral parts of the gland (70% of glandular tissue), most **prostatic carcinomas** arise here, palpable during digital rectal exam
- **transitional zone**: surrounds prostatic urethra (5% of glandular tissue, contains mucosal glands), parenchymal cells undergo hyperplasia and form nodular masses of epithelial cells, can compress the prostatic urethra causing difficult urination (**benign prostatic hyperplasia (BPH)**)
- **periurethral zone**: contains mucosal and submucosal glands, in later stages of BPH this zone may undergo pathologic growth but mainly from stromal compartments
- all glands empty into the **prostatic urethra** \> end site of prostatic ducts (prostatic secretions) and ejaculatory ducts (semen and secretions from seminal vesicles)
34
What is the histological and biochemical components of the prostate gland/secretions?
- glands lined by **simple columnar** or **pseudostratified epithelium**
- lumen contains **corpora amylacea**, concretions rich in glycoproteins and Ca2+ deposits
- prostate prod a Zn-rich alkaline fluid, neutralizes acidic environment of the vagina
- provides nutrients, transports sperm, and liquifies semen
35
Identify the structures in the following images:
- BV: blood vessel
- C: prostatic concretion
- Cap: capsule
- Ep: epithelium
- L: lymphocytes
- SM: smooth muscle
- arrows: inactive alveoli
- arrowheads upper figure: epithelial islands
- arrowheads lower figure insert: basal cells
36
Identify the structures in the following images:
37
- pea-sized structures located in the urogenital diaphragm
- compound tubuloalveolar glands, resemble mucous glands
- lined w/ simple columnar epithelium under the control of testosterone
- secrete preseminal fluid \> lubricate penile urethra, neutralizes traces of acidic urine
bulbourethral glands
38
Describe the structure of the penis:
- consists of cylindrical, columnar masses of erectile tissue: R/L is **corpora cavernosa (2)**, and ventral is **corpus spongiosum (1)** which contains penile urethra
- all 3 erectile tissues are comprised of irregular, interconnected vascular sinuses w/ fibrocollagenous stroma
- **glans penis** is the distal tip of the corpus spongiosum
- corpora cavernosa are each surrounded by a dense fibroelastic layer, the **tunica albuginea**
39
How is an erection produced?
- **erection** involves blood filling the cavernous spaces of erectile tissues, controlled by ANS in the vascular walls:
1) parasympathetics relax trabecular smooth muscle and dilate helicine arteries \> increases blood flow and filling of cavernous spaces
2) enlargement compresses dorsal veins against tunica albuginea \> blocks venous outflow and produces rigidity in erectile tissues
3) at ejaculation, sympathetics constrict helicine arteries and trabecular muscle \> decreases blood flow into spaces, allowing veins to drain most of the blood
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