▪ The male reproductive system consists of ;
1) Paired testes - produce sperm and male hormones
2) Genital ducts ( epididymis , ductus deferens , ejaculatory ducts , urethra ) - carry sperm from testes to outside
body
3) Accessory glands ( seminal vesicles , prostate , bulbourethral glands ) - produce secretions
4) Penis - copulation organ
Testes
▪ Each testis ( testicle ) is surrounded by a dense connective tissue capsule called the tunica albuginea — which
thickens on the posterior side to form the mediastinum testis.
▪ From this fibrous region , septa penetrate the organ and divide it into pyramidal compartments or testicular
lobules .
▪ Each lobule contains sparse connective tissue with endocrine interstitial cells (or Leydig cells) secreting
testosterone , and one to four highly convoluted seminiferous tubules in which sperm production occurs .
▪ Parenchyma :- lobule = seminiferous tubules + straight tubules + stroma
Seminiferous Tubules
▪ Each tubule is actually a loop linked by a very short , narrower segment , the straight tubule , to the rete testis, a
labyrinth of epithelium-lined channels embedded in the mediastinum testis .
▪ The basement membrane of this epithelium is covered by fibrous connective tissue , with an innermost layer
containing flattened , smooth muscle-like myoid cells — which allow weak contractions of the tubule.
* Basal surface = basement membrane + collagen fiber + myoid cells
▪ Each seminiferous tubule is lined with a complex , specialized stratified epithelium called germinal or spermatogenic
epithelium .
* Spermatogenic epithelium = specialized stratified epithelium
▪ The germinal epithelium consists of two types of cells ;
1. Proliferating Spermatogenic cells (male reproductive cells) - produce sperms
2. Sertoli cells ( Sustentacular cells )
▪ Spermatogenic cells is arranged in four or more concentric layers of cells in the germinal epithelium , developed
from progenitor cells to fully formed sperm cells over a period of approximately 10 weeks.
▪ Spermatogenesis is the first part of sperm production involving mainly mitosis and meiosis and is followed by
Spermiogenesis which is the final differentiation process occurring in the haploid male germ cells.
▪ From basal surface to lumen ;
1) Spermatogonia
2) Primary spermatocyte
3) Secondary spermatocyte
4) Spermatid
5) Spermatozoa
1
, ① Spermatogonia
▪ Spermatogenesis begins at puberty with proliferation of stem and small , round progenitor cells called
spermatogonia .
▪ Adjacent to the BM, with round or ovoid nucleus — next to the basement membrane and closely associated with
Sertoli cell surfaces .
▪ Different stages of spermatogonia development can be recognized by subtle changes in shape and staining
properties of their nuclei.
▪ Spermatogonia with dark , ovoid nuclei act as stem cells , dividing infrequently and giving rise both to new stem cells
and to cells with more pale-staining, ovoid nuclei that divide more rapidly as transit amplifying (progenitor) cells .
▪ Classified into :- type Ad , type Ap and type B - [ on the basis of nuclear staining ]
1) Type A - nucleolus in the periphery of nucleus ( Ad - nucleus dark , Ap - nucleus pale )
2) Type B - nucleolus in the center of nucleus
* Type Ad ( stem cells ) → Type Ad → Type Ap → Type B
• These type A spermatogonia each undergo several unique clonal divisions that leave most of the cells
interconnected as a syncytium.
• These become type B spermatogonia, which have more spherical and pale nuclei.
② Primary Spermatocytes
▪ Each type B spermatogonium then undergoes a final mitotic division to produce two cells that grow in size and
become primary spermatocytes — spherical cells with euchromatic nuclei .
▪ The largest cells with nuclei , easily visible , nuclear as woolen ball .
▪ Contain diploid (2n) chromosomes (44+XY) and tetraploid (4n) DNA .
▪ Undergo the first meiosis (homologous chromosomes separate) , producing the secondary spermatocytes.
▪ Stop in the prophase of first meiosis for 22 days .
③ Secondary Spermatocytes
▪ Homologous chromosomes separate in the first meiotic division , which produces smaller cells called secondary
spermatocytes - with only 23 (n) chromosomes (22 + X or 22 + Y) and 2 chromatids and 2N DNA
▪ Smaller cells near the lumen , with round nucleus .
▪ Secondary spermatocytes are rare in testis sections because they are very short-lived cells that remain in interphase
only briefly and quickly undergo the second meiotic division producing spermatids .
④ Spermatids
▪ Division of each secondary spermatocyte separates the chromatids of each chromosome and produces 2 haploid (n)
cells called spermatids — each of which contains 23 chromosomes
▪ The smallest , round or ovoid cells close to the lumen.
▪ Do not divide and transform from round cells into tadpole-like spermatozoa by spermiogenesis .
2
1) Paired testes - produce sperm and male hormones
2) Genital ducts ( epididymis , ductus deferens , ejaculatory ducts , urethra ) - carry sperm from testes to outside
body
3) Accessory glands ( seminal vesicles , prostate , bulbourethral glands ) - produce secretions
4) Penis - copulation organ
Testes
▪ Each testis ( testicle ) is surrounded by a dense connective tissue capsule called the tunica albuginea — which
thickens on the posterior side to form the mediastinum testis.
▪ From this fibrous region , septa penetrate the organ and divide it into pyramidal compartments or testicular
lobules .
▪ Each lobule contains sparse connective tissue with endocrine interstitial cells (or Leydig cells) secreting
testosterone , and one to four highly convoluted seminiferous tubules in which sperm production occurs .
▪ Parenchyma :- lobule = seminiferous tubules + straight tubules + stroma
Seminiferous Tubules
▪ Each tubule is actually a loop linked by a very short , narrower segment , the straight tubule , to the rete testis, a
labyrinth of epithelium-lined channels embedded in the mediastinum testis .
▪ The basement membrane of this epithelium is covered by fibrous connective tissue , with an innermost layer
containing flattened , smooth muscle-like myoid cells — which allow weak contractions of the tubule.
* Basal surface = basement membrane + collagen fiber + myoid cells
▪ Each seminiferous tubule is lined with a complex , specialized stratified epithelium called germinal or spermatogenic
epithelium .
* Spermatogenic epithelium = specialized stratified epithelium
▪ The germinal epithelium consists of two types of cells ;
1. Proliferating Spermatogenic cells (male reproductive cells) - produce sperms
2. Sertoli cells ( Sustentacular cells )
▪ Spermatogenic cells is arranged in four or more concentric layers of cells in the germinal epithelium , developed
from progenitor cells to fully formed sperm cells over a period of approximately 10 weeks.
▪ Spermatogenesis is the first part of sperm production involving mainly mitosis and meiosis and is followed by
Spermiogenesis which is the final differentiation process occurring in the haploid male germ cells.
▪ From basal surface to lumen ;
1) Spermatogonia
2) Primary spermatocyte
3) Secondary spermatocyte
4) Spermatid
5) Spermatozoa
1
, ① Spermatogonia
▪ Spermatogenesis begins at puberty with proliferation of stem and small , round progenitor cells called
spermatogonia .
▪ Adjacent to the BM, with round or ovoid nucleus — next to the basement membrane and closely associated with
Sertoli cell surfaces .
▪ Different stages of spermatogonia development can be recognized by subtle changes in shape and staining
properties of their nuclei.
▪ Spermatogonia with dark , ovoid nuclei act as stem cells , dividing infrequently and giving rise both to new stem cells
and to cells with more pale-staining, ovoid nuclei that divide more rapidly as transit amplifying (progenitor) cells .
▪ Classified into :- type Ad , type Ap and type B - [ on the basis of nuclear staining ]
1) Type A - nucleolus in the periphery of nucleus ( Ad - nucleus dark , Ap - nucleus pale )
2) Type B - nucleolus in the center of nucleus
* Type Ad ( stem cells ) → Type Ad → Type Ap → Type B
• These type A spermatogonia each undergo several unique clonal divisions that leave most of the cells
interconnected as a syncytium.
• These become type B spermatogonia, which have more spherical and pale nuclei.
② Primary Spermatocytes
▪ Each type B spermatogonium then undergoes a final mitotic division to produce two cells that grow in size and
become primary spermatocytes — spherical cells with euchromatic nuclei .
▪ The largest cells with nuclei , easily visible , nuclear as woolen ball .
▪ Contain diploid (2n) chromosomes (44+XY) and tetraploid (4n) DNA .
▪ Undergo the first meiosis (homologous chromosomes separate) , producing the secondary spermatocytes.
▪ Stop in the prophase of first meiosis for 22 days .
③ Secondary Spermatocytes
▪ Homologous chromosomes separate in the first meiotic division , which produces smaller cells called secondary
spermatocytes - with only 23 (n) chromosomes (22 + X or 22 + Y) and 2 chromatids and 2N DNA
▪ Smaller cells near the lumen , with round nucleus .
▪ Secondary spermatocytes are rare in testis sections because they are very short-lived cells that remain in interphase
only briefly and quickly undergo the second meiotic division producing spermatids .
④ Spermatids
▪ Division of each secondary spermatocyte separates the chromatids of each chromosome and produces 2 haploid (n)
cells called spermatids — each of which contains 23 chromosomes
▪ The smallest , round or ovoid cells close to the lumen.
▪ Do not divide and transform from round cells into tadpole-like spermatozoa by spermiogenesis .
2
