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Male reproductive system
TestisMonkey, H & E× 3
• TA: TUNICA ALBUG-
INEA, very dense CT
capsule.
• INCOMPLETE CT
SEPTA radiate from
mediastinum into
parenchyma to
form 250 lobules
per testis.
Testicular tunicae:Most external: visceral tunica vaginalis propria covered by mesothelium
Functional Histology 2004
• Each LOBULUS contains 1-4 seminiferous tubules (ST), lined by GERMINAL
EPITHELIUM. The lenght of one tubule is 30-70 cm!
• This epithelium produces immature spermatozoa.
• The seminiferous epithelium is encircled by a basement membrane and a
WALL formed by collagenous fibers, fibroblasts, and contractile myoid cells.
Myoid cells are responsible for the rhythmic contractile activity that propels
the nonmotile sperm to the rete testis.
Sperm acquire forward motility after they have passed through the
epididymal duct.
• Between the coils of ST lie blood and lymph capillaries, CT fibers,
fibroblasts, mast cells, and testosterone-secreting Leydig interstitial cells.
Lobuli testis
Seminiferous Tubule (ST) is highly coiled, ca 70 cm!
ST is supported by the 1. basal lamina, plus 2 or more alternating 2. layers of
collagen fibres, and 3. muscle-like/myoid cells (M).
Functional
Histology
2004
SPERMATOGENESIS in the germinal epithelium is
initiated by the pituitary hormone FSH and passes
through the stages:
(a) spermatogonium, spheroid cell lying basally
divides mitotically for several generations, then
becomes a
(b) primary spermatocyte, larger, divides by the first
meiotic division (to halve the chromosome number to
haploid 23 and introduce genetic variety), to produce
(c) secondary spermatocytes, small, soon
undergoing the 2nd meiotic division, maintaining
the chromosome number at 23 to give
(d) spermatids, smaller and incompletely
separated, which, without dividing transform by
the process of spermiogenesis - into
(e) spermatozoa, released into the tubule's
lumen.
Spermiogenesis: ovoid spermatids transform into slim, movable spermatozoa, it takes ca. 3 weeks
JUNQUEIRA 2004
Major stages of spermiogenesis
Stevens, Lowe, Histology,
Major stages of spermiogenesis
The development of the flagellum proceeds from a distal centriole:
typical axoneme is surrounded by outer dense fibres and a fibrous sheath;
The proximal part of flagellum called middle pieceis encircled by mitochondria.
Development of the acrosome:
synthesis and storage of hydrolytic enzymes in acrosomal sac is required for fertilization.
Stevens, Lowe, Histology
Functional
Histology
2004
THE SPERMATOZOON is a very elongated motile cell, with a cell membrane
enclosing the:
• acrosomal head cap with an enzyme - proacrosin - to aid binding to and
penetration of the zona pellucida of the oocyte
• nucleus, streamlined in shape, with dense chromatin,
• neck joining the HEAD (nucleus and head cap) to the
• flagellar TAIL
Functional
Histology
2004
TAIL,of a spermatozoon is composed of:
a) middle piece, with an axial axonemal core of microtubules in a cilium-like
array, 9 dense longitudinal fibers (F) and a sheath of mitochondria (Mi)
ending at the annulus (An)
b) principal piece, with both longitudinal and circumferential (Rb) fibres
around the axoneme;
c) end piece, with microtubules like a cilium, however, there are
no dense fibres.
Blood-testis barrier
• Adjacent Sertoli cells are united by band-like, (tight)
occluding junctions.
• These junctions divide the seminiferous tubule into a basal
compartment and an adluminal compartment.
Spermatogenesis is protected to a degree by the tight
attachments between the capillary endothelial cells and,
separately, between the Sertoli cells, creating a two-tiered
blood-testis barrier, for example, against immune attack
(protection of developing sperm cells from autoimmune
reactions).
The inner protected compartment of the seminiferous tubule is
the 'adluminal' compartment.
JUNQUE I RA
2004
Functions of the Sertoli cell
• Structural and metabolic support of differentiating spermatogenic cells.
• They protect, nourish, and release the spermatids.
• Maintain blood-testis barrier
• phagocytose excess cytoplasm (residual bodies) released by maturing
spermatids
• secrete fluid into the lumen that transports spermatozoa through the excretory ducts
• secrete androgen-binding protein (ABP) under the influence of folliclestimulating hormone (FSH) from the anterior pituitary. ABP binds and concentrates testosterone.
• secrete inhibin that inhibits synthesis and release of FSH
Interstitial Leydig cells
• stimulated by the LH hormone of the anterior pituitary they secrete testosterone
• large eosinophilic cells located between seminiferous tubules
• Ultrastracture typical for steroid-secreting cells:
abundant SER, tubular-type mitochondria, smooth
ER, lipid droplets
• Characteristic feature are crystals of Reinecke
Seminiferous tubules continue via straight tubuli recti into cuboidal epithelium-lined ducts of rete testis, which lead through the mediastinum to roughly 6-12 ductuli efferentes.
They take spermatozoa to a
single, coiled, tubular
EPIDIDYMIS located behind
the testis.
DUCTUS DEFERENS is a thick-
walled duct. Peristaltic
contractions of its smooth
muscles moove sperm along
the duct.
JUNQUEIRA 2004
Tests, epididymis, and vas deferens
Paths traversed by spermatozoa
1. Efferent ducts/Ductuli efferentes/Head of epididymis
Unevenly lined by simple, columnar, epithelial cells, in groups of tall ciliated
and short secretory cells: the wall has circular smooth muscle;
functions - reabsorption of the fluid used to move sperm out of the testis;
MATURATION OF THE SPERM.
2. Epididymis/ductus epididymis (body and tail)
Regularly lined by tall, absorptive, columnar principal cells with non-motile
stereocilia, and smaller basal cells, together forming a pseudostratified
columnar epithelium:
outside the basal lamina is a little smooth muscle and, between the coils,
is a stroma of dense connective tissue with capillaries;
FUNCTIONS - AS FOR DUCTULI EFFERENTES.
Maturation of spermatozoa takes place in the epididymis
• Head of epidydimis– Not motile - swim in
circular motion
– Not fertile
• Body of epidydimis – some spermatozoa show
motility
– Some are fertile and may bind to oocyte
• Tail of epidydimis – Normal motility
– Fertile
– Able to bind to oocyte
• Transport of sperm through the epidydimis takes 9-13 days depending on species – and is mandatory
DUCTUS DEFERENS
• Lined by epithelium similar to that of the epididymis, that is
supported by a lamina propria: in the ampulla, this mucosa has
many folds.
• most of the very thick wall is SMOOTH MUSCLE: inner,
longitudinal; middle, circular; outer, longitudinal
• adventitia made of CT binds it to nerves, blood and lymphatic
vessels, and skeletal cremaster muscle, to comprise the
SPERMATIC CORD
FUNCTION - RAPID TRANSPORT OF SPERM DURING EJACULATION,
UNDER CONTROL OF SYMPATHETIC NS.
EJACULATORY DUCTS arise on both sides from the dilation of the ampulla of ductus deferens• Lined by pseudostratified or simple columnar epith that rests on CT, no smooth muscle• Ducts open into the prostatic urethra through a hillock on the posterior urethral wall -verumontanum = colliculus seminalis with its blind recess –utriculus masculinus.
Accessory glands of the male reproductive tract. Three sets of glands connect
to the ductus deferens or urethra: the paired seminal vesicles, the prostate, and the paired bulbourethral glands. Prostate - solid tissue mass which secretes during copulation, secretion contains mainlyionic compounds (NaCl, Na citrate), and a variety of enzymes. Bulbourethral (Cowper's) – small, muscular gland associated with caudal pelvic urethra, contain large volume of stored gel (sialic acid) which is emitted during ejaculation.
Basic Histology, 12 ed.
PROSTATE GLAND: 30-40 tubulo-alveolar glands
Lobulated by septa of CT with much smooth muscle.• Divided, with histology and rectal-probe ultrasound, into several zones:
o peripheral(prone to cancer)o transitionalo centralo periurethral (subject to benign prostatic hyper-trophy
JUNQUEIRA 2004
A diagram of a transverse section of the penis shows the relationships of the three erectile
bodies, tunica albuginea, and major blood vessels.
The corpus spongiosum (CS) is on the ventral side of the penis and surrounds the urethra (U). Two corpora cavernosa (CC) fill the dorsal side and all three bodies of cavernous or erectile tissue are surrounded by dense, fibrous tunica albuginea (TA). Along the dorsal side run the major blood vessels (V) and deep in each mass of erectile tissue are smaller blood vessels (V), including the central arteries. Externally the penis is covered by skin (S) attached to the tunica albuginea or neighboring connective tissue. X15. H&E.
Structure of the penis
ENDOCRINE TESTIS
LEYDIG interstitial CELLS constitute a diffuse, steroid-secreting
endocrine gland; lie outside the tubules' basal lamina. They are
controlled by gonadotrophic Luteinizing Hormone (LH) of the
anterior pituitary, and produce the androgenic hormone.
TESTOSTERONE is responsible for:
(a) spermatogenesis
(b) development and maintenance of reproductive ducts
and accessory glands
(c) secondary sexual characteristics:
- male mating behaviour
- anabolic effects on metabolism.