①Distribution: close to the base film

② Morphology: small size, round cells, round nuclei, 12 microns in diameter, dark staining, 1 to 2 nucleoli, karyotype 46 XY

③Characteristics: The most immature spermatogenic cells differentiate into primary spermatocytes

④ Splitting begins during adolescence

①Distribution: proximal luminal side of spermatogonia

②Shape: Larger, 18 microns in diameter, large and round nucleus, filamentous chromatin, karyotype 46 XY

③Features: Visible in slices,

①Distribution: near the luminal side of primary spermatocytes

②Shape: Small size, round nucleus, dark staining, karyotype 23 X or 23 Y

③ Features: Hard to see in slices

①Distribution: close to the lumen surface

②Shape: 8 microns in diameter, small and round nucleus, dark coloring, karyotype 23 X or 23 Y

③ Features: No more splitting

④Sperm formation

①Distribution: Luminal surface

②Form

LM: The cells are high pyramidal or high columnar, with a wider base and close to the basement membrane. The top extends to the luminal surface, and the cell outline is unclear. The nuclei are mostly located at the base and are triangular, oval or irregular in shape, with light staining and obvious nucleoli.

EM: There are a large number of smooth endoplasmic reticulum and some rough endoplasmic reticulum, a well-developed Golgi apparatus, more mitochondria, lysosomes, microfilaments and microtubules

Tight junctions are formed near the base of the lateral surface to divide the seminiferous epithelium into

❶Constitute blood-testis barrier

❷Support and nourish spermatogenic cells

❸Promote spermatogenic cells to move toward the lumen and release sperm into the lumen

❹phagocytosis of cytoplasm shed during sperm formation

❺Synthesize and secrete androgen binding protein