Histology Of Male Reproductive System Flashcards
The male reproductive system is composed of
- Testes
- Genital ducts
- Accessory glands
- Penis
Primary functions of the male reproductive system
Sperm and testosterone production
What is the metabolite for testosterone?
Dihydrotestosterone
Testosterone is important for:
◦Spermatogenesis
◦Sexual differentiation during embryonic and fetal development
◦Control of gonadotropin secretion in the pituitary
Dihydrotestosterone acts on…
… male accessory glands and hair follicles
Function of the genital ducts and accessory glands
- Secretions for sperm activity
- their contraction helps to propel spermatozoa and the secretions from the penile urethra
Semen is composed of…
…sperm-nourishing secretions and spermatozoa
Each testis is surrounded by…
…a capsule of dense connective tissue called the tunica albuginea
On what part of the testes does the tunica albuginea thicken and what is formed?
It thickens on the posterior aspect of the testis to form the mediastinum testis
What arises from the mediastinum testis to penetrate the organ and divide it into pyramidal compartments or lobules? How many are the lobules?
Septa; about 250 to 1000
Each lobule of the testis is occupied by…
…one to four seminiferous tubules
The seminiferous tubules are surrounded by
interstitial tissue rich in blood and lymphatic vessels, nerves and interstitial cells of Leydig
•The seminiferous tubules produce _____ while Leydig cells secrete _____
spermatozoa, androgens
During fetal development, as the testes migrates from the abdominal cavity to the scrotal sac, they carry with them ___
a serous sac, the tunica vaginalis, derived from the peritoneum
The tunica vaginalis consists of…
…an outer parietal layer lining the scrotum and an inner visceral layer covering the tunica albuginea on the anterior and lateral sides of the testis
At what temperature does spermatogenesis occur?
Below 37oC
Interstitial tissue is located between seminiferous tubules. True or false?
True
The interstitial tissue surrounding the seminiferous tubules consist of…
dispersed connective tissue containing:
◦Fibroblasts
◦Lymphatics
◦Blood vessels including fenestrated capillaries
During puberty, interstitial cells or Leydig cells develop as…
…large round or polygonal cells with central nuclei and eosinophilic cytoplasm rich in small lipid droplets
Which cells produce testosterone in the testes?
Interstitial cells or Leydig cells
Testosterone secretion by the interstitial cells is triggered by…
…the pituitary gonadotropin- luteinizing hormone (LH) or interstitial cell stimulating hormone (ICSH)
Where are testosterone-stimulating gonadotropins in the body during puberty?
The hypothalamus produces gonadotropin-releasing hormone
Where are testosterone-stimulating gonadotropins in the body during embryonic development?
The placenta
Sperm are produced in the seminiferous tubules at a rate of…
… 2 x 108 per day in the young adult
Size of a lobule
about 150-250 µm in diameter and 30-70 cm in length
The combined length of the tubules of one testis is about
250 m
Each tubule consists of a ___ , linked to the ___ via a short, narrower segment, called the ___
convoluted loop, rete testis, straight tubule or tubuli recti
The rete testis is lined with ___ and embedded in ___
Epithelium, mediastinum testis
The rete testis is connected to the head of the epididymis by…
About 10-20 efferent ductules
Each seminiferous tubule is lined with…
… a specialized stratified epithelium called germinal or spermatogenic epithelium
The spermatogenic epithelium consists of…
… two types of cells:
- Non-dividing cells (Sertoli cells) - Support precursor cells
- Dividing (Proliferative) cells of the spermatogenic lineage
The cells of the spermatogenic lineage comprises of…
4 or more cell layers which develop from progenitor cells to mature sperm cells over a period of about 10 weeks
The development from progenitor cells to mature sec cells takes…
10 weeks
Sperm production begins with ___ and ends with ___
Spermatogenesis, Spermiogenesis
Spermatogenesis begins at puberty with…
…proliferation (rapid increase) of stem and progenitor cells called spermatogonia
Spermatogonia are located…
…basally in the epithelium next to the basement membrane and in close association with the Sertoli cells
Diameter of spermatogonia
About 12 µm in diameter
The different stages of spermatogonia development are differentiated by…
…changes in shape and staining properties of their nuclei
What are the largest cells of the spermatogenic lineage?
Primary spermatocytes
Spermiogenesis is…
the final stage in sperm production and is the process by which spermatids transform into spermatozoa
Soermiogenesis is a temperature-sensitive process that requires cell division. True or false?
False. It is temp-driven, but requires no cell division
The spermatids are positioned where?
Near the lumen of the seminiferous tubules and remain in close association with Sertoli cells
Size of spermatids
7-8 µm in diameter
Spermiogenesis involves:
- Formation of the acrosome
- Condensation and elongation of the nucleus
- Development of the flagellum, and
- The loss of much of the cytoplasm
The end result of spermiogenesis is…
…the mature spermatozoon which is released into the lumen
What are the phases of spermiogenesis?
There are 4:
- Golgi phase
- Cap phase
- Acrosome phase
- Maturation phase
Sertoli cells were named after
Enrico Sertoli (1842-1910)
What are Sertoli cells?
They are tall columnar or pyramidal cells that to a large extent, envelop all cells of the spermatogenic lineage
Function of Sertoli cells
They function as supporting (metabolic and physical) cells or nurse cells
Sertoli cells divide the seminiferous tubules into…
2 compartments: Basal and Adluminal
Sertoli cells adhere to ___ and their apical ends extend into ___
the basal lamina, the lumen
Each Sertoli cell supports…
30-50 germ cells at various stages of development
The blood-testis barrier is formed by…
…elaborate tight occluding junctions between the basolateral membranes of adjacent Sertoli cells
Functions of the blood-testis barrier
It is one part of a system that prevents autoimmune attacks against the spermatogenic cells
Functions of Sertoli cells
- Support, protection and nutrition of the developing spermatogenic cells
- Exocrine and endocrine secretions
- Phagocytosis
Sertoli cells are stimulated by FSH to secrete…
- Androgen-binding protein (ABP)
- estradiol
- inhibin
- mullerian-inhibiting substance (MIS)
The intratesticular ducts carry spermatozoa and liquid from the seminiferous tubules to the epididymis. True or false?
True
Components of the intratesticular ducts
◦Straight tubules or tubuli recti
◦Rete testis
◦Efferent ductules
The initial segment of the straight tubule is lined only by ____ while the distal segment is lined with ___
Sertoli cells, Cuboidal epithelium and supported by connective tissue of the mediastinum
Rete testis drains into how many efferent ductules?
About 20
Rete testis are lined by…
…by an unusual epithelium composed of groups of nonciliated cuboidal cells alternating with groups of taller ciliated cells, giving them a characteristic scalloped appearance
The walls of the efferent ductules contain…
…a thin layer of smooth muscle cells that facilitate the movement of sperm into the epididymis
Function of the Excretory genital ducts
They transport sperm from the scrotum to the penis during ejaculation
The excretory genital ducts include the:
◦Epididymis
◦Ductus (Vas) deferens and
◦Urethra
Length of the duct of the epididymis
6m
The epididymal duct forms the…
head, body and tail of the epididymis which lies along the superior and posterior sides of each testis
The epididymal duct is lined by…
…pseudostratified columnar epithelium containing stereocilia
Sperm are stored in the epididymis and attain their various final characteristics including:
◦Motility
◦Membrane receptors for zona pellucida proteins
◦Maturation of the acrosome, and
◦Ability to fertilize
Properties of ductus (vans) deferens
- Long straight tube with a thick, muscular wall
- Narrow lumen and a thick layer of smooth muscle
The ductus deferens is lined along most of its length by…
…pseudostratified columnar epithelium with parse stereocilia
Properties of the lamina propria and muscularis in the ductus deferens
The lamina propria is rich in elastic fibers and the thick muscularis consists of longitudinal inner and outer layers and a middle circular layer
Layers of the muscularis of the vans deferens
External - Longitudinal
Middle - Circular
Fate of the ductus deferens after the urinary bladder
After passing over the urinary bladder, the ductus deferens dilates to form an ampulla in which the epithelium is thicker and more extensively folded
Where do the seminal vesicles join the ductus deferens?
At the final portion of the ampulla
The segment of the vans entering the prostate is called
the ejaculatory duct
What enters the prostate gland and opens into the prostatic urethra?
The ductus deferens
The mucosa of the ductus deferens continues through the ejaculatory duct, but the muscle layers disappears beyond the ampulla. True or false?
True
Function of the accessory glands
They produce secretions that are added to sperm during ejaculation to produce semen
The accessory glands include the:
◦Seminal vesicles
◦Prostrate and
◦Bulbourethral glands
The two seminal vesicles consists of highly tortuous tubes about 10 cm in length. True or false?
False. Their length is 15cm.
The unusual mucosa of the seminal vesicles display…
a great number of thin, complex folds that fill most of the lumen
The folds of the seminal vesicles are lined with…
…simple or pseudostratified columnar epithelial cells rich in secretory granules
The seminal vesicles are exocrine glands that produce a viscid, yellowish secretion containing:
◦Fructose ◦Citrate ◦Inositol ◦Prostaglandins ◦Fibrinogen ◦Enzymes and other proteins
Importance of semen excretions
- Make up about 70% of the ejaculate
- Nutrient source for the sperm
◦Coagulate semen after ejaculation
Prostate gland location
It is a dense organ surrounding the urethra below the bladder
Size and weight of the urinary bladder
It is approximately 2 cm x 3 cm x 4 cm in size and weighs about 20 g.
Components of the prostate gland
It is a collection of 30-50 branched tubuloalveolar glands, all surrounded by a dense fibromuscular stroma covered by a capsule
Layers of the prostate gland
The glands are arranged in 3 concentric layers around the urethra:
◦Inner layer of mucosal glands
◦Intermediate layer of submucosal glands and
◦Peripheral layer with the prostate’s main glands
Zones of the prostate gland
It has 3 zones:
◦Transition zone - 5% of the volume
◦Central zone - 25%
◦Peripheral zone - 70%
The tubuloalveolar glands of the prostate are lined by a
simple or pseudostratified columnar epithelium.
Function of the prostate gland
The glands produce prostatic fluid, containing various glycoproteins and enzymes and store this fluid for expulsion during ejaculation
●A rich fibromuscular stroma surrounds the glands
●The prostate is surrounded by a fibroelastic capsule
●Septa from this capsule penetrate the gland and divides it into indistinct lobes
Septa from the prostate’s fibroelastic capsule penetrate the gland and divides it into indistinct lobes. True or false?
True
Importance of the prostate specific antigen (PSA)
It is an important secretion of the prostate, high blood levels of which markprostatic carcinoma or inflammation
Features of the corpora amylacea
◦These are prostatic concretions are often partially calcified, normally present in the lumen
◦They have no physiologic or clinical significance
◦The number increases with age
The bulbourethral glands (Cowper’s glands) are located in the ___ and empty into the ___
urogenital diaphragm, penile urethra
Epithelium of Cowper’s gland is lined by…
… a mucus-secreting simple columnar epithelium
The main components of the penis are:
are 3 cylindrical masses of erectile tissue, plus the penile urethra, surrounded by skin:
2 dorsal corpora cavernosa
1 corpus spongiosum surrounding the urethra
Most of the penile urethra is lined with…
…pseudostratified columnar epithelium and becomes stratified squamous epithelium at the glans
The corpora cavernosa are covered by…
…a layer of dense connective tissue, the tunica albuginea
The corpora cavernosa and the corpus spongiosum are both composed of erectile tissue. True or false?
True
