Normal: Normal adult male testicular tissue consists of seminiferous tubules and interstitium. (1) Seminiferous tubules: they contain spermatogenic cells at all levels (spermatogonia, spermatocytes, sperm cells, spermatozoa, etc.) and supporting cells (Sertoli cells), which are often not easily seen because secondary spermatocytes exist for a short time during spermatogenesis. The supporting cells are larger in size and their cytosol extends from the basement membrane straight to the luminal surface of the tubule, which has the functions of secretion, nutrition, phagocytosis, support of spermatogenic cells and release of spermatozoa, and constitutes the blood-testis barrier. (2) Boundary membrane: outside the lumen of seminiferous tubules is a thin and neat boundary membrane, also called the intrinsic membrane, which is divided into three layers, from the inside to the outside in the order of cell-free layer (basement membrane), myocyte-like layer, lymphatic endothelial cells and fibroblast layer, which is a component of the blood-testis barrier and has the functions of contraction, material exchange and phagocytosis. (3) Interstitium: The interstitium is loose connective tissue containing L-eydig cells, macrophages, blood vessels, lymphatic vessels, and fibrous tissue. Abnormalities: Abnormal findings: (1) Spermatogenic epithelial detachment type: the seminiferous tubules are dilated, most or all of the tubular lumen is filled with detached spermatogenic cells, and the lumen disappears, often with different degrees of boundary membrane and small blood vessel changes. (2) Spermatogenic block or maturation disorder: the spermatogenic process is often blocked at the spermatocyte or spermatocyte stage, often accompanied by spermatogenic cells, boundary membrane and vascular changes, which is a differentiation abnormality of the spermatogenic process. (3) Hypospermatogenic type: The spermatogonia and spermatozoa at all levels are uniformly reduced, the supporting cells show a large number of vacuoles, the lumen is dilated, and the immature spermatogonia, boundary membranes and blood vessels that are shed at an early stage are seen without obvious changes. (4) Hyaline degeneration type: Extensive hyaline degeneration, atrophy and lumen narrowing of seminiferous tubules, and in severe cases, “phantom tubules”, often accompanied by extensive fibrosis and vascular hyaline degeneration. This is a manifestation of autoimmune reaction, which may be caused by non-specific inflammation, viral mumps combined with orchitis, drug effects, or may be the result of unexplained or other pathological damage. (5) Support cell only syndrome: absence or disappearance of germ cells in the seminiferous tubules, only support cells are present, the diameter of the seminiferous tubules is small, the boundary membrane and interstitial lesions are severe, it can be divided into: ① primary (congenital): it is caused by the germ cells in the yolk sac not developing or not descending to the germinal ridge during the embryonic period, the testis size and sexual characteristics are abnormal. (2) Acquired (secondary): It is a late result of various testicular lesions. (6) Mixed type: There are more than two types of tissue alterations, often with difficult to distinguish between primary and secondary, manifesting as spermatogenic cell epithelial detachment, impaired maturation, and hyaline degeneration. In addition, there are also testicular hypoplasia or development-impeded lesions, such as immature testes of Creutzfeldt-Jakob syndrome, which often show small testes, poorly developed secondary sexual characteristics, testicular lesions are consistent, and may have chromosomal abnormalities, which are easily diagnosed. (7) The relationship between testicular biopsy histological typing and prognosis: spermatogenic epithelial detachment, the best prognosis, hypospermatogenic function still has a therapeutic basis, hyaline degeneration, only support cell syndrome, spermatogenic disorders, Kern’s syndrome, etc. have no therapeutic basis, poor prognosis.