Histology π¬ Flashcards
what is the male productive system formed of?
formed of 2 main parts:
- Primary sex organs: Two testes
- Accessory sex organs: Male genital ducts, Accessory genital glands & penis
what type of gland is the testis?
compound tubular mixed exocrine and endocrine gland
what is the testis composed of?
composed of supporting stroma and parenchyma.
Stroma of the testis
1. Tunica vaginalis: (A fold of peritoneum)
- A serous sac formed of an outer parietal &
inner visceral layer separated by a space.
2. Tunica albugenia:
- A capsule of dense fibrous C.T. Thickened posteriorly to form mediastinum testis.
3. Septa (trabeculae):
- Incomplete septa dividing the testis into
about 250 testicular lobules.
4. Reticular fibres
parenchyma of the testis
1. Exocrine parenchyma: (Sperms)
- Seminiferous tubules & duct system.
2. Endocrine parenchyma: (Sex hormones)
- Leydig cells & fenestrated blood capillaries.
what is the definition of seminiferous tubules?
The exocrine portion of the testis that produces spermatozoa
what is the number of seminiferous tubules?
1-4 seminiferous tubules in each lobule.
what is the structure of seminiferous tubules?
- Separated by connective tissue called the interstitial tissue containing: nerves, lymphatics, interstitial cells (Leydig cells) and fenestrated blood capillaries.
- Highly tortuous compound tubular gland.
- Has a clear basement membrane surrounded by fibrous C.T. with smooth muscle-like cells (myoid cells).
what are the types of cells in seminiferous tubules?
Lined by 2 types of cells:
1- Spermatogenic cells
2- Sertoli cells
what are Spermatogenic cells arranged in?
- Spermatogenic cells are arranged in 4-8 concentric layers lying on the basement membrane and are given different names in the different stages of their development.
1. Spermatogonia
2. Primary spermatocytes
3. Secondary spermatocytes
4. Spermatids
5. Spermatozoa
when do spermatogonia start maturing into primary spermatocytes?
- After puberty, spermatogonia start maturing into primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa in a process known as spermatogenesis.
Spermatogenesis
- Spermatogenesis is divided into 3 phases: mitosis, meiosis and spermiogenesis:
ββββ-
1- Mitosis is the differentiation of spermatogonia into primary spermatocytes. Spermatogonia (dark type A, pale type A and type B) (mitosis) β Primary spermatocytes.
__________________
2- Meiosis is the first and second meiotic divisions to transform primary spermatocytes to secondary spermatocytes and spermatids respectively.
Primary spermatocytes (1st meiosis) β Secondary spermatocytes (2nd meiosis) β Spermatids.
________________
3- Spermiogenesis is the conversion of spermatids into mature spermatozoa. Spermatids (spermiogensis) β Mature sperms.
what is the origin of spermatogonia?
From primordial germ cells.
site of spermatogonia
1-2 layers on the basement membrane.
shape of spermatogonia
Rounded
what are the changes that happen to spermatogonia?
Origin, site, shape & changes in Primary, Secondary spermatocytes and spermatids
what is Spermiogenesis?
It is the morphological changes which occur in the spermatid to be changed into mature sperm (without cell division).
what are changes that happen in Spermiogenesis?
what is the length of mature spermatozoon?
Long (65 ΞΌm long)
structure of Mature spermatozoon
The mature spermatozoon consists of:
1. Head
2. Neck
3. Tail:
a. Middle piece b. Principal piece c. End piece
Length, Shape & Structure of parts of spermatozoon
Site of Sertoli Cells
between spermatogenic cells extending from the basement membrane to the lumen.
L/M of Sertoli Cells
Shape: Tall columnar cells with irregular lateral surfaces. βwith invaginations that hold spermatogoniaβ
Nucleus: Basal oval nucleus.
Cytoplasm: Pale cytoplasm.
E/M of Sertoli Cells
- Sertoli cells are joined to each other by tight junctions forming the blood- testis barrier.
- The cytoplasm contains numerous lysosomes, sER, mitochondria and Golgi apparatus.
what are the functions of Sertoli Cells?
- Providing spermatogenic cells with nutritive factors. βselectiveβ
- Preventing auto-immune reactions by isolating spermatocytes and sperms from the host immune system through the blood-testis barrier.
- Secretion of androgen-binding protein (ABP) which concentrates intra-testicular testosterone in sufficient levels to support spermatogenesis.
- Phagocytosis of degenerated cells and excess cytoplasm βresidual bodiesβ shed off during spermiogenesis.
what is Blood-testis barrier?
Continuous tight junctions between lateral borders of Sertoli cells.
what does the Blood-testis barrier divide the seminiferous tubule into?
https://youtu.be/71h_9Juq57Y
Divides the seminiferous tubule into 2 compartments:
Outer (basal) compartment:
- Only spermatogonia
Inner (adluminal) compartment:
- Primary spermatocytes.
- Secondary spermatocytes.
- Spermatids.
- Mature spermatozoa.
How do formed spermatogenic cells pass the BTB to the lumen?
- Newly formed primary spermatocytes temporarily disassemble the blood-testis barrier and move to the inner adluminal compartment. During this process, junctions disassemble above the translocating cells and at the same time, new junctions assemble below.
(Like an elevator)
Definition of Leydig Cells
The endocrine portion of the testis that produces testosterone
Site of Leydig Cells
In the interstitial tissue lying between the seminiferous tubules.
L/M of Leydig Cells
Shape: Large polygonal cell.
Nucleus: Central rounded nucleus.
Cytoplasm: Acidophilic Vacuolated. (Lipid content)
E/M of Leydig Cells
The cytoplasm is rich in:
1. Numerous lipid droplets.
2. Mitochondria with tubular cristae. (like cells in ZF of adrenals)
3. Numerous sER.
Function of Leydig Cells
Synthesis of testosterone hormone
what are ducts related to male genital system?
Intra-testicular:
- Tubuli recti
- Rete testis
Extra-testicular:
- Vasa efferentia
- Epidydimus
- Vas deferens
- Ejaculatory duct
- Urethra
Site of Tubuli Recti
Small straight tubules at the end of Seminiferous tubules
Lining epithelium of Tubuli Recti
- In the proximal portion: Sertoli cells
- In the distal portion: Simple cubical
Site of Rete testis
Narrow branching tubules in Mediastinum testis
Lining epithelium of Rete testis
simple cubical
Site of Vasa Efferentia (Efferent Ductules)
Extending from rete testis pierce tunica albuginea to head of epididymis
Structure of Vasa Efferentia (Efferent Ductules)
- Epithelial Lining: Alternating Simple cuboidal non ciliated & simple columnar ciliated epith.
Function of Vasa Efferentia (Efferent Ductules)
Transport sperm from rete testis to epididymis
Site of Epididymis
On the posterior surface of the testis
Structure of Epididymis
- Long highly coiled duct formed of head, Body & Tail
1) Epithelium: Pseudostratified columnar with Stereocilia (Long microvilli, not true cilia)
2) Vascular CT & Smooth muscle fibers
Function of Epididymis
- Biochemical maturation & short-term storage of sperms
- Phagocytosis of residual bodies
- Transport sperm from Vasa efferentia to Vas deferens
Site of Vas Deferens (Ductus Deferens)
- Begins from epididymis in scrotum
- Ascends within spermatic cord & passes through Inguinal canal
- Reaches posterior aspect of Urinary bladder
- Expands to form the Ampulla
- Joins duct of seminal vesicle forming the Ejaculatory duct
Structure of Vas Deferens (Ductus Deferens)
Function of Vas Deferens (Ductus Deferens)
Transports sperm by rapid powerful peristaltic contraction from epididymis to the ejaculatory ducts
Site of Ejaculatory ducts
- Formed by union of vas deferens and duct of seminal vesicle
- It penetrates the prostate and opens in the prostatic urethra
Lining epithelium of Ejaculatory ducts
Pseudostratified columnar or Simple columnar epithelium
Function of Ejaculatory ducts
Transport sperm from vas deferens to urethra
Compare between prostatic, membranous & penile urethras according to length, site, epithelium & function
Summary of male genital ducts
what is the type of Seminal Vesicles?
These are paired highly tortuous tubular glands
Site of Seminal Vesicles
Posterior to urinary bladder
length and size of Seminal Vesicles
Each about 15 cm long
Structure of Seminal Vesicles
Function of Seminal Vesicles
- Exocrine glands that secrete Viscid Yellowish alkaline fluid that makes up 70% of the ejaculate.
- This fluid contains:
1) Fructose: Major energy source of sperm.
2) Fibrinogen: Slight Coagulation of semen after ejaculation