Lakhasly

o Spermatogenesis can be divided into four (4) stages: 3.1.o Spermatogonia Ad represent the first cellular stage of spermatogenesis itself, it divides into 2 Spermatogonia B. o Spermatogonia B differentiate into 2 Spermatocyte type I. o The multiplication and differentiation of these cells is regulated by the tyrosine kinase receptor (cKIT) protein.o Spermiogenesis includes 6 fundamental phenomena which are practically simultaneous: a. Formation of the acrosome from the Golgi apparatus: Acrosomic granule is produced in the Golgi apparatus and grows over the nucleus.The molecular mechanism is still poorly understood yet, it is dependent on FSH and testosterone.f.Spermiation: is the final process during which mature spermatozoa are delivered into the lumen of Seminiferous Tubules for their subsequent maturation in the epididymis.o Spermatozoa is pushed out into the tubule lumen via the extension of a microtubule-rich Sertoli cell cytoplasmic stalk (tige cytoplasmique).The microtubules of the distal centriole elongate and organize into an axoneme that elongates and emerges from the cell by pushing back the plasma membrane.e.Removal of cytoplasm: detachment of the cytoplasm forming the residual body, which is subsequently digested by Sertoli cells via phagocytosis.Proliferation (multiplication, Spermatocytogenesis) o Two types of spermatogonia A (spermatogonium) are present in the basal compartment of the ST, Spermatogonia Ad (dark type) and Ap (pale type).o This process involves two successive meiotic divisions: meiosis I and meiosis II. o During meiosis I (23 days), diplotene Spermatocyte I (2N:2C) is transformed into 2 Spermatocyte II (1N:2C).Maturation (Meiosis) o The transition from diploid primary spermatocytes to haploid spermatids.3.3.3.3.

• Spermatogenesis can be divided into four (4) stages:
3.1. Proliferation (multiplication, Spermatocytogenesis)
• Two types of spermatogonia A (spermatogonium) are present in the basal compartment of
the ST, Spermatogonia Ad (dark type) and Ap (pale type).
• Spermatogonia Ap have a self-renewal property and thus are predominant.
• Spermatogonia Ad represent the first cellular stage of spermatogenesis itself, it divides into
2 Spermatogonia B.
• Spermatogonia B differentiate into 2 Spermatocyte type I.
• The multiplication and differentiation of these cells is regulated by the tyrosine kinase
receptor (cKIT) protein.
3. Stages of Spermatogenesis3.2. Growth
• It concerns spermatocytes I and corresponds schematically to the interphase and the
beginning of the prophase of the first meiotic division.
• The size of the cells increases by accumulation of synthesized material (25 μm). They are
called Auxocytes.
• The growth phase during spermatogenesis is shorter than in oogenesis.
3. Stages of Spermatogenesis3.3. Maturation (Meiosis)
• The transition from diploid primary spermatocytes to haploid spermatids.
• This process involves two successive meiotic divisions: meiosis I and meiosis II.
• During meiosis I (23 days), diplotene Spermatocyte I (2N:2C) is transformed into 2
Spermatocyte II (1N:2C).
• Spermatocyte II is then transformed into 2 round Spermatids (1N:1C) via meiosis II (24
hours). Meiosis II resembles a typical mitotic division.
• Four (4) haploid spermatids are the products of the two meiotic divisions of each
spermatocyte I.
3. Stages of Spermatogenesis3.4. Transformation (Spermiogenesis, differentiation)
• Spermiogenesis is the process during which spermatids are transformed into spermatozoa
(23 days).
• Spermiogenesis includes 6 fundamental phenomena which are practically simultaneous:
a. Formation of the acrosome from the Golgi apparatus: Acrosomic granule is produced in
the Golgi apparatus and grows over the nucleus. Its enzymatic content will be essential for
crossing the envelopes of the oocyte during fertilization.
b. Formation of the flagellum: The 2 centrioles migrate to the pole opposite the acrosome.
The microtubules of the distal centriole elongate and organize into an axoneme that
elongates and emerges from the cell by pushing back the plasma membrane.
3. Stages of Spermatogenesisc.Nuclear elongation: The nucleus gradually elongates and densifies. The anterior 2/3 of the
nucleus are covered by the acrosome.
d. Formation of the mitochondrial sleeve: Mitochondria are arranged end to end in a spiral,
constituting the mitochondrial sleeve of the Intermediate piece (the midpiece). At its distal
end, the sleeve is limited by a dense ring described as the annulus.
e.Removal of cytoplasm: detachment of the cytoplasm forming the residual body, which is
subsequently digested by Sertoli cells via phagocytosis. The molecular mechanism is still
poorly understood yet, it is dependent on FSH and testosterone.f.Spermiation: is the final process during which mature spermatozoa are delivered into the
lumen of Seminiferous Tubules for their subsequent maturation in the epididymis.
• Spermatozoa is pushed out into the tubule lumen via the extension of a microtubule-rich
Sertoli cell cytoplasmic stalk (tige cytoplasmique).
• Sertoli cells facilitate the removal of cytoplasmic remnants, ensuring that only streamlined,
functional spermatozoa are released.
• In the epididymis, under the action of androgens, spermatozoa acquire their mobility, and
they temporarily lose their ability to fuse with other membranes (decapacitation).
• Sperm can be stored in the epididymis and survive there for about three (3) weeks.
3. Stages of SpermatogenesisStages of SpermatogenesisSpermiogenesis