Spermatogenesis Flashcards
STAGES OF SPERMATOGENESIS:
- SPERMATOCYTOGENESIS
- SPERMATIDOGENESIS
- SPERMIOGENESIS
consists of a series of mitotic division of spermatogonia ending in production of primary spermatocytes
spermatogcytogenesis
The creation of spermatids from a
primary spermatocytes and eventually secondary spermatocytes after they undergo a series of meiosis
SPERMATIDOGENESIS
It is the differentiation or metamorphosis
stage of spermatids into mature
spermatozoa.
SPERMIOGENESIS
During SPERMIOGENESIS phase, the round spermatids undergo dramatic changes which includes?
formation of acrosomes, condensation and elongation of the nucleus, development of the flagellum or tail and the loss of redundant substances of the cytoplasm and its organelles
SPERMATOGENIC CELLS STAGES:
- SPERMATOGONIUM
- PRIMARY SPERMATOCYTES
- SECONDARY SPERMATOCYTES
- SPERMATIDS
- SPERMATOZOA
The primordial male germ cells that are the precursors of spermatozoa multiply by mitosis to become spermatocytes throughout adult life
SPERMATOGONIUM
The primordial male germ cells that are the precursors of spermatozoa multiply by mitosis to become?
Primary spermatocytes
are what arise after immature germ cells, spermatogonia, go through mitosis.
Primary spermatocytes
They are diploid cells which means that they have two sets of
chromosomes.
Primary spermatocytes
are haploid cells, Smaller than primary spermatocytes, and show coarse chromatin granules and abundant rough endoplasmic reticulum cisternae.
Secondary spermatocytes
Secondary spermatocytes rapidly undergo the
second?
meiotic division.
Is the haploid male sex cell formed after the completion of meiotic divisions, they give rise to the mature spermatozoa after undergoing differentiation
SPERMATIDS
the mature male sex cell capable of fertilizing the ovum characterized by having a compact head a long flagella for swimming
SPERMATOZOA
Becomes replacement cells that provides continuous
production of sperm cells
Spermatogonium
THE SEMINIFEROUS TUBULES located within the?
testis
it is the site the spermatozoa production
SEMINIFEROUS TUBULES
The seminiferous tubules are lined by?
Sertoli and spermatogenic cells arranged in layers
The seminiferous tubules are surrounded by a?
basement membrane consisting of an outer thin parietal epithelium overlying peritubular myoid cells, collagen, and an inner layer of extracellular matrix.
Includes the spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa.
GERM CELLS or SPERMATOGENIC CELLS
are larger and less numerous that nourishes the developing spermatozoa.
It produces both androgen binding protein and inhibin.
SERTOLI (NURSE) CELLS
are found in the parenchyma of the testes between the seminiferous tubules.
LEYDIG (INTERSTITIAL) CELLS
stimulates Leydig cells to produce testosterone and small quantities of other androgens
Luteinizing hormone
This space contains small blood vessels and interstitial cells or Leydig cells.
interstitial spaces
composed of extracellular matrix that serves to separate them from the interstitial compartment, provides structural integrity to the tubules, and regulates the function of cells in contact with it.
BASAL LAMINA
resides between the basement membrane and junctional complexes. It contains diploid spermatogonia that rest upon the basement membrane.
basal compartment
is the region from the junctional complexes to lumen of the seminiferous tubules. This compartment contains the spermatocytes, spermatids and the fully differentiated mature spermatozoa which migrated from the basal compartment.
adluminal compartment
THE BLOOD-TESTIS BARRIER Also called?
Sertoli Cell barrier
is a structural and physiologic barrier created by inter-Sertoli-cell tight junctions. It is one of the tightest blood-tissue barrier in the mammalian body. It divides the seminiferous tubules into the basal compartment and the adluminal compartment
blood-testis barrier
The primary function of the blood-testis barrier is to?
create a protected environment in adluminal compartment for the development of sperm.
• It acts as physical barrier between the blood vessels and the seminiferous tubules to isolate the cellular events of spermatogenesis and provide an ideal environment during the process
• It separates the developing sperm from the immune system so the immune system does not attack and destroy the sperms because they are genetically different from the male
THE BLOOD-TESTIS BARRIER
• Maintain the environment necessary for development and maturation of the spermatogenic cells segrete substances initiating meiosis
• Secrete supporting testicular fluid
• Secrete androgen-binding protein (ABP), which concentrates testosterone in close proximity to the developing gametes
• Testosterone is needed in very high quantities for maintenance of the reproductive tract, and ABP allows a much higher level of fertility
• Secrete hormones affecting pituitary gland control of spermatogenesis, particularly the polypeptide hormone, Inhibin Phagocy to senesidual cytoplasm left over from spermiogenesis
• Secretion of anti-Milerian hormone causes deterioration of the Müllerian duct
• Protect spermatids from the immune system of the male, via the blood-testis barrier
• Contribute to the spermatogonial stem cell niche
SERTOLI OR NURSE CELLS
SPERMIOGENESIS also called?
SPERMATELEOSIS
• The final stage of spermatogenesis where the spermatids undergoes morphologic changes or differentiation into the streamline spermatozoa adapted for fertilization
• Occurs while the spermatids are embedded in small hollows in the free luminal surface of the Sertoli Cells in the seminiferous tubules within the testis
Spermiogenesis
STAGES OF SPERMIOGENESIS
- Golgi phase
- Cap phase
- Acrosomal phase
- Maturation phase
- This is the phase where spermatids begin to develop polarity
- Midpiece forms
- Mitochondria gathers towards the midpiece
- Distal Centriole begins to form an Axoneme
- DNA undergoes packaging and becomes tightly condensed
GOLGI PHASE
attached to the Sertoli Cell
ANTERIOR POLE
points towards the lumen
POSTERIOR POLE
creates enzymes that will become the acrosome at the anterior pole
Golgi apparatus
- The Golgi apparatus surrounds the condensed nucleus, becoming the acrosomal cap
- The distal centriole forms the axoneme and continue to project away from the nucleus towards the lumen of the seminiferous tubule forming the flagallum
CAP PHASE
The Golgi apparatus surrounds the condensed nucleus, becoming the?
acrosomal cap
forms the axoneme and continue to project away from the nucleus towards the lumen of the seminiferous tubule forming the flagallum
distal centriole
- The nucleus begins to elongate
- The acrosome eventually covers the majority of the anterior nucleus
- The Manchette forms in the region of the caudal half of the nucleus and extends down toward the developing flagellum The neck and the annulus are formed
- The plasma membrane completely surrounds the developing spermatid
ACROSOMAL PHASE
- Mitochondria form a spiral assembly around the flagellum that defines the Middle Piece
- The Postnuclear Cap is formed from the manchette microtubules
- The annulus forms the juncture between the middle piece and principal piece
- The excess cytoplasm is released as residual bodies and will be phagocytosed by the Sertoli Cells
MATURATION PHASE
form a spiral assembly around the flagellum that defines the Middle Piece
Mitochondria
is formed from the manchette microtubules
Postnuclear Cap
forms the juncture between the middle piece and principal piece
annulus
• The process by which fully differentiated spermatozoa are released from the supporting somatic Sertoli cells into the lumen of the seminiferous tubules.
• It is the critical determinant of the number of sperm entering the epididymis and thus the sperm content of the ejaculate
• The resulting spermatozoa are now. mature but lack motility, rendering them
sterile
SPERMIATION
SPERMIATION is the process by which fully differentiated spermatozoa are released from the supporting somatic Sertoli cells into the?
lumen of the seminiferous tubules
Factors Affecting The Rate And Quality Of Spermatogeneis:
• Hormones
• Temperature
• Dietary Deficiencies
• Radiation
• Infectious Diseases
• Exposure to certain metals and drugs
What are the characteristics of normal sperm?
- Oval-shaped head
- Intact midpiece
- Uncoiled single tail
- Able to swim well and in a straight line
- Contains healthy genetic information with the correct number of chromosomes