35. Male Reproductive Histology Flashcards
The testes are posteriorly associated with the epididymis and both are suspended by the ______
The testes are enclosed by the _________, which thickens to form the mediastinum, where the _______ is located
Spermatic cord
Tunica albuginea; rete testis
Septa form 250-300 _____ within the testes, each with 1-4 _______ ______
Lobules; seminiferous tubules
Seminiferous tubules consist of a central lumen lined by a specialized seminiferous epithelium, composed of _______ and _______ cells
Somatic sertoli; spermatogenic
The ____ _____ is a network of spaces contained within the CT of the mediastinum
Rete testes
Epithelium of the seminiferous tubules is surrounded by a _____ _____ consisting of multilayered CT, collagen, and 3-5 layers of myoid cells
Lamina propria
________ cells are found in between the seminiferous tubules
Leydig (interstitial)
The wall of seminiferous tubules consists of peritubular _____ cells separated from the seminiferous epithelium by a basement membrane
Myoid
Seminiferous epithelium is _________ epithelium with unusual characteristics. It is made up of _____ ______ sertoli cells which interact with ______, ______, and _____
Stratified; somatic columnar; spermatogonia; spermatocytes; spermatids
Of the cells that somatic columnar sertoli cells interact with:
____ are mitotic
_____ are meiotic
_______ are haploid, and undergoing spermatogenesis
Spermatogonia
Spermatocytes
Spermatids
The seminiferous epithelium houses different structural types of nuclei:
Nuclei of ______ and _______ are closely associated with tubular wall
Nuclei of _________ cells are larger and contain clumps of chromatin
Nuclei of _______ are round and light
Nuclei of ________ are cylindrical, and condensed
Spermatogonia; sertoli cells
Spermatogonial cells (primary spermatocytes)
Early spermatids
Late spermatids
[note that early and late spermatids’ nucli lie close to the lumen]
_____ cells extend the full thickness of the seminiferous epithelium, and the nucleus is basally located with a large nucleolus
Sertoli
Sertoli cells’ apical and lateral membranes have an irregular outline - why?
To provide niches and crypts to hous developing spermatogenic cells
Functions of sertoli cells:
- support, protect, and nourish developing spermatogenic cells
- eliminate _________ via phagocytosis (discarded by spermatids during _______)
- release of mature spermatids into lumen of tubule in process called ________
Residual bodies; spermiogenesis
Spermiation
On micrographs, sertoli cells have _____ or ______ nuclei and distinct ______
Oval; pyramidal; nucleoli
At basolateral domain, sertoli cells have tight junctions creating ______ and _______ compartments (this is special to the testes as usually it is an apical specialization)
Basal; adluminal
In the basal compartment of seminiferous epithelium, spermatogonial cells are housed in ______, which allows greater access to nutrients and signaling molecules
In the adluminal compartment, tight junctions establish the _________ which protects developing spermatocytes and spermatids from autoimmune reactions as well as selects nutrients needed for spermatogenic cells
Niches
Blood-testes barrier
Spermatocytes are located above the blood-testis barrier, most of which are ______ spermatocytes
Primary
Leydig cells are present in the ______ space, close to blood vessels
They are _____-producing cells that contain lipid droplets, mitochondria with tubular cristae, and a well developed sER
They also produce 95% of the body’s ______
Intertubular
Steroid
Testosterone
Leydig cell function is regulated by the 2 hormones of the AP, _____ which stimulates testosterone production, and ______ which induces the expression of the LH receptor
LH; Prolactin
______ regulates the synthesis of steroids in Leydig cells by transporting cholesterol across the outer mitochondrial membrane. A mutation in the gene encoding this protein is detected in individuals with a defective synthesis of adrenal and gonadal steroids
StAR (steroidogenic acute regulatory protein)
In the sequence of spermatogenesis:
A spermatogonial cell arises from a _______ ___ cell which will initiate a spermatogenic cell sequence or will retain stem cell capacities via mitosis (this ensures continuous sperm production)
After division, spermatogenic cells remain interconnected by intercellular bridges and cytokinesis is incomplete
Primordial germ
T/F: each cohort of spermatogonia, spermatocytes, and spermatids complete their growth and differentiation in a timely manner, proliferating and differentiating synchronously
True
Diploid spermatogenic cells reside in a ___ of basal compartment of sertoli cells, located ______ the blood testis barrier
Niche; outside
What is the difference between type A and type B spermatogonia?
Type A: Oval, euchromatic nucleus and nucleolus attahed to nuclear envelope (subclasses dark and pale); type A clonally divide (mitosis), generating copies of itself or differentiating into type B
Type B: round nucleus, masses of heterochromatin attached to nuclear envelope and central nucleolus; divide (mitosis) and cells immediately enter meiotic prophase as primary spermatocytes (ensures 2x DNA when starting meiosis prophase I)
________ divide by 2 meiotic divisions. They are located in adluminal compartment above sertoli cell tight junctions. Meiosis occurs _____ the blood testes barrier
Spermatocytes; inside
__________ _______ undergo 1st meiotic division (reductional division) to produce 2 _____ _______, which undergo the 2nd meiotic division (equational division) to produce 2 __________, which mature without further division
Primary spermatocytes; secondary spermatocytes; spermatids
Describe DNA content at the end of meiosis I of spermatocytes
DNA content of primary spermatocyte (4N) is reduced in a secondary spermatocyte (2N)
Describe DNA content at the end of meiosis II of spermatocytes
DNA content of secondary spermatocyte (2C) is reduced in a spermatid (1C); spermatids are haploid and initiate spermiogenesis
Compare duration of 1st and 2nd meiotic division of spermatocytes
1st meiotic division is long (days) but 2nd is very short (minutes)
[Primary spermatocytes are most abundant cells observed in seminiferous epithelium]
Haploid spermatids are located in the adluminal compartment, in proximity to lumen of seminiferous tubules
______ (early) spermatids, are housed in niches in the cytoplasm of sertoli cells
_______ (late) spermatids, housed in crypts, deep invaginations in sertoli apical cytoplasm
Round
Elongated
Spermatids are engaged in _______, a differentiated cell process (the last step of spermatogenesis)
Spermiogenesis
What takes place during spermiogenesis?
Development of the acrosome
Development of the manchette
Development of the tail
Shaping and condensation of the nucleus
Mature spermatids are released into the seminiferous tubular lumen via _______, which involves contractile forces generated by sertoli cells
Spermiation
Spermiation consists of the release of mature spermatids over a period of several days, from the apical edge of ______ cells to the lumen of _______
Sertoli; seminiferous tubule
During spermiation, intercellular bridges that linked spermatids form _____ ____, which are lost during maturation and mature spermatids are separated
Residual bodies
During spermiation, spermatids become non-motile sperm upon release into the lumen of seminiferous tubules. They are propelled to the epididymal duct, where they undergo a maturation process, resulting in forward _____ for fertilization capability
Motility
Mature sperm consist of the head and tail, surrounded by a plasma membrane.
The head contains a flattened, condensed, and elongated nucleus. It is partially capped by the _______ which covers the anterior 1/2 of the nucleus and contains ______ enzymes
The tail is subdivided into 3 segments: ______, _____ and _____
Acrosome; hydrolytic
Middle piece, principal piece, and end piece
The middle piece of the sperm tail consists of:
A helically arranged ______ sheath
An axoneme
9 longitudinal columns, _______ fibers, surrounding the axoneme, and projecting down the tail
Mitochondrial; outer dense
The principal piece of the sperm tail is the longest segment; it consists of the central ______ surrounded by a ______ sheath which provides scaffold during sliding/bending of the tail during forward motility
Axoneme; fibrous
The _____ piece of the sperm tail consists of a very short segment that only contains axoneme
End
Trace the sperm maturation pathway
Straight tubules (tubulus recti) —> rete testis —> efferent ductules —> epididymal duct
Columnar sertoli cells only mark the transition from the seminiferous epithelium to the _____ _____.
Basal tight junctions between columnar sertoli cells change into apical tight junctions between the _____ sertoi cells at the tubulus rectus and rete testis. The apical domain of the cuboidal sertoli cells displays ______ and an occasional primary cilium.
Tubulus rectus (straight tubules)
Cuboidal; microvilli
Along the sperm maturation pathway, the straight tubules are located in the mediastinum of the testis. They are lined with ____ ____ epithelium. The sertoli cells have tight junctions at the apical domain and no spermatogenic cells are present
Simple cuboidal
Irregularly anastomosing channels within the mediastinum of the testes
Rete testis
Rete testis epithelium
Simple cuboidal
T/F: The wall of straight tubule has tall sertoli cells which becomes simple cuboidal epithelium in the rete testis
True
About 12-20 _________ link the rete testis to the epididymis
Efferent ductules
Each efferent ductule is lined with what types of cells? What are their functions?
Columnar cells with microvilli/sterocilia: reabsorbs fluid from lumen
Ciliated cells: assist in transport of nonmotile sperm
Basal cells: precursor of ciliated and nonciliated cells
A thin inner circular layer of sm muscle underlies the epithelium and ____ of efferent ductules
Basal lamina
________ epithelium has hallmark scalloped outline that enables ID of efferent ductules
Pseudostratified
The _____ is a highly elongated and coiled duct where sperm mature
Epididymis
The epididymis is made up of head (caput), body (corpus), and tail (cauda).
It is lined with _____ ____ epithelium with long and branched ______
Pseudostratified; stereocilia
What cell types make up the epididymis?
Principal cells: columnar (extend from lumen to BL, apical domain displays branched stereocilia, well developed golgi, lysosomes, and vesicles)
Basal cells (undifferentiated precursors of principal cells)
Sperm maturation consists in acquiring forward motility — mature sperm are stored in the terminal portion of the epididymal. The epididymal duct is surrounded by a thin layer of smooth muscle, which facilitates the ____ of sperm
Peristalsis
The epididymis is covered by a _____ and the ______
Capsule; tunica vaginalis
Sperm are transported from head region of epididymis to tail by peristalsis (stored in tail until ejaculation)
Fertilizing ability is acquired from the ____to ____ of epididymis, and time of maturation is ___-___ days
Body; tail; 2-12
Sperm maturation includes:
Stabilization of condensed ______
Changes in plasma membrane surface ____
Acquisition by sperm of new surface _____
Acquisition of sperm forward _____
Chromatin
Charge
Proteins
Motility
The vas deferens is a 45 cm long muscular tube lined with ________ epithelium with _____, supported by a CT lamina propria w/ elastic fibers
The muscular wall is made up of inner and outer longitudinal layers as well as a middle circular layer
Pseudostratified colunar w/ stereocilia/stereovilli
The external layer of the vas deferens consists of loose CT and _________
The ______ is the dilated portion that leads directly into the prostate gland; the distal end of which receives the ducts of the seminal vesicle, forming the ________
Adipocytes
Ampulla; ejaculatory ducts
The wall of the veins of the _______ has a thick 3-layer muscularis and can be mistaken for arteries on histological slides of the spermatic cord
Pampiniform plexus
The fascicles of the striated ____ muscle can be seen at the periphery of the spermatic cord on histological slides
Cremaster
Accessory genital glands in males
Seminal vesicles (2) Prostate gland (1) Bulbourethral glands (2) Urethral glands of Littre
What accessory genital glands produce the majority of seminal fluid
Seminal vesicles and prostate gland
The function of seminal vesicles and prostate gland is regulated by androgens (____ and____)
Testosterone; DHT
Seminal vesicles are _____-dependent organs that are outpocketings of each vas deferens (ampulla), consisting of an external CT ______, middle smooth muscle layer (inner circular and outer longitudinal), and highly folded mucosa lined by ______-to-______ ____ epithelium
Androgen; capsule; simple cuboidal-to-pseudostratified columnar
T/F: seminal vesicles store some sperm
False; their function is to secrete an alkaline viscous fluid rich in fructose (energy source) and prostaglandins
The prostate gland is a muscular and glandular organ. The glands empty into the prostate urethra via long excretory ducts. The prostatic urethra is end site of _______ and ______ ducts
Prostatic; ejaculatory
The prostate gland is arranged into what 3 zones? What glands are found in each?
Central zone; periurethral mucosal glands
Transition zone; periurethral submucosal glands
Peripheral zone; branched (compound) glands
70-80% of prostate cancer originates in _______ zone
Peripheral
The prostate is surrounded by a capsule consisting of 30-50 branched ______ glands
Tubuloalveolar
The branched tubuloalveolar glands of the prostate are lined by _____or _________ epithelium; the lumen contains _________ — concretions rich in glyoproteins and Ca deposits
Simple or pseudostratified; corpora amylacea
The penis consists of a right and left ________ as well as a ventral _______ which contains the penile urethra
Corpora cavernosa; corpus spongiosum
The columns that make up the penis converge to form the shaft; the ____ ___ is the distal tip of the corpus spongiosum
Glans penis
The structures in the penis are surrounded by an elastic CT fascia, and each erectile tissue cylinder is surrounded by dense CT capsule called the ____
Tunica albuginea
Erectile tissues are comprised of large, irregular vascular sinuses with _________ stroma
Vascular sinuses are supplied by numerous _____ arteries
Fibrocollagenous
Helicine
