Male Reproductive system histology
It consists of the
Testes
Genital ducts
Accessory glands
Penis
Testes
Testes produces sperm but also contain endocrine cells secreting hormones (testosterone which is
important for spermatogenesis, sexual differentiation, control of gonadotropin secretion)
Each testis is surrounded by dense connective tissue (tunica albuginea) it thickens on the posterior
side and forms the mediastinum testis. It then penetrates the testes and divides into 250-300
pyramidal compartments called Testicular lobules. Each lobule contains spars connective tissue with
endocrine interstitial cells (Leydig cells) which secretes testosterone.
Testes develops retroperitoneally in the dorsal wall of the embryonic abdominal cavity and they are
moved during fetal development and becomes suspended in a scrotal sac at the ends of the
spermatic cords. Testes also contains tunica vaginalis which is derived from the peritoneum, it
consists of outer parietal layer lining the scrotum and an inner visceral layer coving the tunica
albuginea on anterior and lateral sides.
Sperm formation occurs at about 34C and it is maintained by the scrotum sac in multiple
mechanism:
Testicular artery is surrounded by pampiniform venous plexus which contains cold blood
from the testis and it draws heat from the arterial blood by a heat exchange system.
Evaporation of sweat from the scrotum helps in heat loss.
Relaxation of the thin dartos muscle of the scrotum and the cremaster muscles of the
spermatic cords move the testis away (decreases temperature) while contraction moves it
closer (increases temperature)
Interstitial tissue (Leydig cells)
It is a tissue of the testis between the seminiferous tubules consists of spars connective tissue
containing fibroblasts, lymphatics, and blood vessels (including fenestrated capillaries)
During puberty the interstitial cells develop as large round or polygonal cells with central nuclei and
eosinophilic cytoplasm rich in small lipid droplets.
The Leydig cells produces testosterone (promotes development of the secondary male
characteristics). Testosterone is synthesized by enzymes present in the smooth ER and mitochondria.
The secretion of testosterone is activated by pituitary gonadotropin, Interstitial cell-stimulating
hormone (ICSH) (another name is luteinizing hormone (LH)).
, The synthesis of testosterone begins when the hypothalamus begins producing gonadotropin
releasing hormone. (These cells are very active during 3 rd & 4th months of pregnancy then they slow
down and become quiescent cells resembling fibroblasts until puberty)
Seminiferous tubules
Sperm are produced here. Each testes has from 250-1000 seminiferous tubules in its lobules. Each
tubule is loop linked by straight tubule (very short, narrow segment) to the rete testis (Labyrinth of
epithelium lined channels embedded in the mediastinum testis) Then about 10-20 efferent ductulus
connect the rete testis to the head of the epididymis.
Seminiferous tubules are lined with a complex, specialized stratified epithelium called germinal or
spermatogenic epithelium. The basement membrane is covered by fibrous connective tissue with an
innermost layer containing flattened smooth muscle like myoid cells (Allows for weak contractions of
the tubule)
Germinal epithelium consists of 2 type of cells:
Large nondividing Sertoli cells (support developing sperm cell precursors)
Dividing cells of the spermatogenic lineage
The cells of spermatogenic lineage develop from progenitor cells to fully formed sperm cells in 10
weeks.
Spermatogenesis (Formation of sperm cells)
It begins at puberty with proliferation of stem and progenitor cells called Spermatogonia, they
occupy a basal niche in the epithelial wall of the tubules next to the basement membrane and
closely associated with Sertoli cell surfaces.
Stages of spermatogonia are recognized by small changes in shape and staining properties of the
nuclei. Spermatogonia with dark, ovoid nuclei act as stem cells, dividing infrequently and giving rise
to new stem cells and to progenitor cells. Progenitor cells with pale-staining, ovoid nuclei, divides
frequently
Type A spermatogonia (Stem cells & Progenitor cells) undergo several unique clonal divisions that
leave most of the cells interconnected as a syncytium, which become type b spermatogonia and they
have more spherical and pale nuclei. Each type B spermatogonium undergoes a mitotic division to
produce 2 cells which grow in size and become primary spermatocytes (spherical cells with
euchromatic nuclei).
Primary spermatocytes are the largest cells of the spermatogenic lineage and are characterized by
the presence of partially condensed chromosomes in various stages of synapsis and recombination
Primary spermatocyte has 46 chromosomes and DNA content of 4N, they enter the first meiotic
prophase (3 weeks). Secondary spermatocytes are produced with 23 chromosomes and DNA content
of 2N. Secondary spermatocytes are very short lived and remain in interphase.
Division of each secondary spermatocyte separates the chromatids of each chromosome and
produces 2 haploid cells called spermatids with 23 chromosomes and DNA content of 1N
It consists of the
Testes
Genital ducts
Accessory glands
Penis
Testes
Testes produces sperm but also contain endocrine cells secreting hormones (testosterone which is
important for spermatogenesis, sexual differentiation, control of gonadotropin secretion)
Each testis is surrounded by dense connective tissue (tunica albuginea) it thickens on the posterior
side and forms the mediastinum testis. It then penetrates the testes and divides into 250-300
pyramidal compartments called Testicular lobules. Each lobule contains spars connective tissue with
endocrine interstitial cells (Leydig cells) which secretes testosterone.
Testes develops retroperitoneally in the dorsal wall of the embryonic abdominal cavity and they are
moved during fetal development and becomes suspended in a scrotal sac at the ends of the
spermatic cords. Testes also contains tunica vaginalis which is derived from the peritoneum, it
consists of outer parietal layer lining the scrotum and an inner visceral layer coving the tunica
albuginea on anterior and lateral sides.
Sperm formation occurs at about 34C and it is maintained by the scrotum sac in multiple
mechanism:
Testicular artery is surrounded by pampiniform venous plexus which contains cold blood
from the testis and it draws heat from the arterial blood by a heat exchange system.
Evaporation of sweat from the scrotum helps in heat loss.
Relaxation of the thin dartos muscle of the scrotum and the cremaster muscles of the
spermatic cords move the testis away (decreases temperature) while contraction moves it
closer (increases temperature)
Interstitial tissue (Leydig cells)
It is a tissue of the testis between the seminiferous tubules consists of spars connective tissue
containing fibroblasts, lymphatics, and blood vessels (including fenestrated capillaries)
During puberty the interstitial cells develop as large round or polygonal cells with central nuclei and
eosinophilic cytoplasm rich in small lipid droplets.
The Leydig cells produces testosterone (promotes development of the secondary male
characteristics). Testosterone is synthesized by enzymes present in the smooth ER and mitochondria.
The secretion of testosterone is activated by pituitary gonadotropin, Interstitial cell-stimulating
hormone (ICSH) (another name is luteinizing hormone (LH)).
, The synthesis of testosterone begins when the hypothalamus begins producing gonadotropin
releasing hormone. (These cells are very active during 3 rd & 4th months of pregnancy then they slow
down and become quiescent cells resembling fibroblasts until puberty)
Seminiferous tubules
Sperm are produced here. Each testes has from 250-1000 seminiferous tubules in its lobules. Each
tubule is loop linked by straight tubule (very short, narrow segment) to the rete testis (Labyrinth of
epithelium lined channels embedded in the mediastinum testis) Then about 10-20 efferent ductulus
connect the rete testis to the head of the epididymis.
Seminiferous tubules are lined with a complex, specialized stratified epithelium called germinal or
spermatogenic epithelium. The basement membrane is covered by fibrous connective tissue with an
innermost layer containing flattened smooth muscle like myoid cells (Allows for weak contractions of
the tubule)
Germinal epithelium consists of 2 type of cells:
Large nondividing Sertoli cells (support developing sperm cell precursors)
Dividing cells of the spermatogenic lineage
The cells of spermatogenic lineage develop from progenitor cells to fully formed sperm cells in 10
weeks.
Spermatogenesis (Formation of sperm cells)
It begins at puberty with proliferation of stem and progenitor cells called Spermatogonia, they
occupy a basal niche in the epithelial wall of the tubules next to the basement membrane and
closely associated with Sertoli cell surfaces.
Stages of spermatogonia are recognized by small changes in shape and staining properties of the
nuclei. Spermatogonia with dark, ovoid nuclei act as stem cells, dividing infrequently and giving rise
to new stem cells and to progenitor cells. Progenitor cells with pale-staining, ovoid nuclei, divides
frequently
Type A spermatogonia (Stem cells & Progenitor cells) undergo several unique clonal divisions that
leave most of the cells interconnected as a syncytium, which become type b spermatogonia and they
have more spherical and pale nuclei. Each type B spermatogonium undergoes a mitotic division to
produce 2 cells which grow in size and become primary spermatocytes (spherical cells with
euchromatic nuclei).
Primary spermatocytes are the largest cells of the spermatogenic lineage and are characterized by
the presence of partially condensed chromosomes in various stages of synapsis and recombination
Primary spermatocyte has 46 chromosomes and DNA content of 4N, they enter the first meiotic
prophase (3 weeks). Secondary spermatocytes are produced with 23 chromosomes and DNA content
of 2N. Secondary spermatocytes are very short lived and remain in interphase.
Division of each secondary spermatocyte separates the chromatids of each chromosome and
produces 2 haploid cells called spermatids with 23 chromosomes and DNA content of 1N
