ANAT2241 Male Reproductive System

From Embryology

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ANAT2241 This practical support page content is not part of the virtual science practical class and provides additional information for student self-directed learning purposes. All practical class pages are located on Moodle - ANAT2241

General Objective

To know the histological and cytological structures of the major components of the male reproductive system.

Specific Objectives

  1. To describe the microanatomy of the testis and epididymis.
  2. To identify cells of the germinal epithelium of the seminiferous tubule: Sertoli cells, spermatogonia, spermatocytes, spermatids and spermatozoa.
  3. To know the main events occurring in spermiogenesis.
  4. To know the structure of the ductus deferens, seminal vesicle, prostate gland and penis.

Learning Activities

Examine the following virtual slides, and in course manual identify, draw and label the structures and note their function.

Virtual Slides: Male Reproductive System

See also Female Reproductive System

Testis Histology

Convoluted Seminiferous Tubules

  • tubules are enclosed by a thick basal lamina and surrounded by 3-4 layers of smooth muscle cells (or myoid cells).
  • tubules are lined with seminiferous epithelium consisting of two cell types: spermatogenic cells and Sertoli cells.


  • first cells of spermatogenesis.
  • originate in week 4 of fetal development in the endodermal walls of the yolk sac and migrate to the primordium of the testis, where they differentiate into spermatogonia.
  • Spermatogonia remain dormant until puberty. They are always in contact with the basal lamina of the tubule.
  • Two types of spermatogonia can be distinguished in the human seminiferous epithelium:

** Type A spermatogonia have a rounded nucleus with very fine chromatin grains and one or two nucleoli. They are stem cells which divide to form new generations of both type A and type B spermatogonia. 
** Type B spermatogonia have rounded nuclei with chromatin granules of variable size, which often attach to the nuclear membrane, and one nucleolus. Although type B spermatogonia may divide repeatedly, they do not function as stem cells and their final mitosis always results in the formation of primary spermatocytes.

Primary spermatocytes

  • lie in the cell layer luminal to the spermatogonia.
  • appear larger than spermatogonia.
  • immediately enter the prophase of the first meiotic division, which is prolonged (about 22 days).
  • large number of primary spermatocytes is always visible in cross-sections through seminiferous tubules.
  • cell divisions, from the formation of primary spermatocytes and onwards, to the production of the spermatocytes, are incomplete.
  • cells remain connected by bridges of cytoplasm.
  • completion of the first meiotic division results in the formation of secondary spermatocytes

Secondary spermatocytes

  • smaller than primary spermatocytes.
  • rapidly enter and complete the second meiotic division (seldom seen in histological preparations).
  • division results in the formation of spermatids.


  • lie in the luminal part of the seminiferous epithelium.
  • small cells (about 10 µm in diameter) with an initially very light (often eccentric) nucleus.
    • chromatin condenses during the maturation of the spermatids into spermatozoa, and the nucleus becomes smaller and stains darker.
  • terminal phase of spermatogenesis is called spermiogenesis
    • consists of the morphological differentiation of the newly formed spermatids into spermatozoa.
Testis histology 1.jpg
Seminiferous-tubule-HEx40.jpg Testis histology 2.jpg


Spermatozoa animation icon.jpg This brief animation shows an overview of the structural components of the spermatozoa.
  1. Blue - Nucleus containing male haploid genome required to combine with oocyte haploid genome to form diploid zygote.
  2. Red - Acrosome containing enzymes required to digest the zona pellucida. The acrosome develops as a highly modified golgi structure.
  3. Green - Centriole and axonema required for spermatozoa movement.
  4. Orange - Mitochondria and annulus required for energy for spermatozoa movement.
  5. Grey - Cytoplasm and plasmolemma, cell membrane containing membrane proteins for chemotaxis and binding to the oocyte zone pellucida.

  • mature human spermatozoon is about 60 µm long and actively motile.
  • divided into head, neck and tail.
    • head - (flattened, about 5 µm long and 3 µm wide) chiefly consists of the nucleus (greatly condensed chromatin!). The anterior 2/3 of the nucleus is covered by the acrosome, which contains enzymes important in the process of fertilisation. The posterior parts of the nuclear membrane forms the so-called basal plate.
    • neck - short (about 1 µm) and attached to the basal plate. A transversely oriented centriole is located immediately behind the basal plate. The neck also contains nine segmented columns of fibrous material, which continue as the outer dense fibres into the tail.

    • tail - further divided into a middle piece, a principal piece and an end piece. The axonema (arrangement of microtubules in all cilia) begins in the middle piece. It is surrounded by nine outer dense fibres, which are not found in other cilia. In the middle piece (about 5 µm long), the axonema and dense fibres are surrounded by a sheath of mitochondria. The middle piece is terminated by a dense ring, the annulus. The principal piece is about 45 µm long. It contains a fibrous sheath, which consists of dorsal and ventral longitudinal columns interconnected by regularly spaced circumferential hoops. The fibrous sheath and the dense fibres do not extend to the tip of the tail. Along the last part (5 µm) of the tail, called the end piece, the axonema is only surrounded by a small amount of cytoplasm and the plasma membrane.
<html5media height="400" width="400">File:Spermatozoa_animation.mp4</html5media>

Epididymis Histology

Pseudostratified Epithelium
  • Nuclei of the epithelial cells are typically located in the widest part of the cell.
    • the nuclei of cells that do or do not reach the surface of the epithelium are often located at different heights within the epithelium, giving the epithelium a "stratified" appearance.
  • The epithelium though is not stratified, therefore named "pseudostratified".
Testis histology 023.jpg
Epididymis histology 02.jpg Epididymis histology 03.jpg

Human Testis (adult)

Human Testis (young)

Testis Histology Links: Testis Development | Spermatozoa Development | Histology

Human (young): overview labeled | overview unlabeled | convoluted seminiferous tubules x10 | x40 | x40 | tunica albuginea x20
Human (adult): overview x2 | convoluted seminiferous tubules labeled | x10 | x20 | x40 | x40 | epididymis ductulus efferens | ductus epididymidis | epithelium | overview x4 | x10 | x20 | x40 | ductus deferens labeled overview | epithelium | overview x2 | x10 | x40
Human spermatozoa: x20 | x40 | x100
Human Stage 22: Testis - labeled overview | Testis - unlabeled overview | Testis - unlabeled detail | Testis - labeled detail | testis | Carnegie stage 22 | Movie - Urogenital stage 22
Rabbit: convoluted seminiferous tubules x20 | x100
Mouse: postnatal epididymis | 14 days postnatal | 33 days postnatal | 45 days postnatal | 2 months postnatal
Spermatozoa Development (expand to see terms)  

Spermatozoa Development

Note there are additional glossaries associated with genital, spermatozoa, oocyte and renal.

  • acroplaxome - structure forms the acrosome plate with intermediate filament bundles of the marginal ring at the leading edge of the acrosome. The sub-acrosomal layer located in the developing spermatozoa head perinuclear region, located between the inner acrosomal membrane and the nuclear envelope. The other part of the perinuclear region is the post-acrosomal sheath (PAS) at the post-acrosomal region.
  • acrosome - Cap-shaped cellular structure formed from the golgi apparatus and contains enzymes to dissolve the oocyte (egg) zona pellucida for fertilisation.
  • acrosome compaction - Acrosome reshaping process in final stages of spermatogenesis (spermatid to spermatozoa).
  • acrosome reaction - Chemical change within the spermatozoa following binding to the zona pellucida, only acrosome reacted spermatozoa have an ability to fuse with oocytes.
  • annulus - Cytoskeletal (septin) structure located between the midpiece and principal piece regions of the tail, thought to form a diffusion barrier between these two domains. PMID 20042538
  • asthenozoospermia - (asthenospermia) Term for reduced sperm motility and can be the cause of male infertility.
  • axoneme - (axonema) The basic structure in cilia and eukaryotic flagella and in the spermatozoa tail, consisting of parallel microtubules in a characteristic "9 + 2" pattern. This pattern describes 9 outer microtubule doublets (pairs) surrounding 2 central singlet microtubules, in humans 50 μm long. The motor protein dynenin move the outer microtubules with respect to the central pair, bending the cilia and generating motility. Note that prokaryotic bacteria have a similar process (flagellum) that uses an entirely different mechanism for motility.
  • capacitation - term describing the process by which spermaozoa become capable of fertilizing an oocyte, requires membrane changes, removal of surface glycoproteins and increased motility.
  • caput - proximal head of the epididymis, epithelium with stereocilia, involved in absorbing fluid to concentrate spermatozoa. Underlying smooth muscle aids movement. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
  • CatSper - cationic (Ca2+) channel of spermatozoa, progesterone activated involved in hyperactivation, acrosome reaction, and possibly chemotaxis.
  • cauda - distal tail of the epididymis, region with a thin epithelium and the greatest quantity of smooth muscle. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
  • centriole - a microtubule organising centre. First required for axoneme formation (distal centriole) that is lost and a second for pronuclei formation (proximal) following fertilisation. Rodents loose both and only have maternal centrioles.
  • connecting piece - linkage between the spermatozoa head and the midpiece of the tail. PMID 22767409
  • corpus - elongated body of the epididymis, This has an intermediate thickness of epithelium and thicker smooth muscle layer than caput. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
  • cytoplasmic bridges - Transient cytoplasm connections between spermatids arising from one spermatogonium due to incomplete cytokinesis.
  • diploid - (Greek, di = double + ploion = vessel) Having two sets of chromosomes, the normal state for all cells other than the gametes.
  • end piece - Last portion of the spermatozoa tail region.
  • epididymis - testis tubular structure connecting the efferent ducts to the ductus deferent and functions for the storage and maturation of spermatozoa. Epididymis three main parts : caput (head), corpus (body), cauda (tail). PMID27307387
  • fibrous sheath - cytoskeletal structure surrounding the axoneme and outer dense fibers, defining the extent of the principal piece region.
  • haploid - (Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (oocyte, spermatozoa) following reductive cell division by meiosis. Normally cells are diploid, containing 2 sets of chromosomes.
  • interstitial cell - (Leydig cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus.
  • interstitium - testis developmental region (space between testis cords) that generates Leydig cells and other less well characterized cell types.
  • Johnsen score - a clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article. PMID 5527187
  • Leydig cell - (interstitial cell) Male gonad (testis) cell that secrete the androgen testosterone, beginning in the fetus. Fetal Leydig cells develop from coelomic epithelium and undifferentiated perivascular cells in the gonad–mesonephros border region. Adult Leydig cells appear after birth from stem/progenitor cells among peritubular and peri-vascular cells. Leydig cells were first histologically identified in 1850 by Franz von Leydig (1821 - 1908) a German scientist.
  • meiosis - The cell division that occurs only in production of germ cells where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. All other non-germ cells in the body divide by mitosis.
  • midpiece - (middle piece) spermatozoa tail initial segment of axoneme surrounded outer dense fibres then by mitochondria. Next in the tail is the principal piece then finally the end piece.
  • mitosis - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.
  • outer dense fibres - (ODF, outer dense fibers) cytoskeletal structures that surround the axoneme in the middle piece and principal piece of the spermatozoa tail.
  • primary spermatocyte - arranged in the seminiferous tubule wall deep (luminal) to the spermatogonia. These large cells enter the prophase of the first meiotic division. (More? meiosis)
  • principal piece - Spermatozoa tail segment containing the plasma membrane calcium channels (CatSper1 and CatSper2) required for hyperactivation of motility. Region is partially separated from the midpiece by a barrier called the annulus.
  • sertoli cells - (sustentacular cell) These cells are the spermatozoa supporting cells, nutritional and mechanical, as well as forming a blood-testis barrier. The cell cytoplasm spans all layers of the seminiferous tubule. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
  • sperm annulus - (Jensen's ring; Latin, annulus = ring) A region of the mammalian sperm flagellum connecting the midpiece and the principal piece. The annulus is a septin-based structure formed from SEPT1, 4, 6, 7 and 12. Septins are polymerizing GTPases that can act as a scaffold forming hetero-oligomeric filaments required for cytokinesis and other cell cycle roles.
  • spermatogenesis - (Greek, genesis = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called spermiogenesis.
  • spermatogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm shape and organization. This process involves reorganization of cellular organelles (endoplasmic reticulum, golgi apparatus, mitochondria), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation).
  • spermatogonia - The cells located in the seminiferous tubule adjacent to the basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
  • spermatozoa head - Following spermiogenesis, the first region of the spermatozoa containing the haploid nucleus and acrosome. In humans, it is a flattened structure (5 µm long by 3 µm wide) with the posterior part of nuclear membrane forming the basal plate region. The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and spermatozoa tail).
  • spermatozoa neck - Following spermiogenesis, the second region of the spermatozoa attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail. In humans, it forms a short structure (1 µm). The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and tail).
  • spermatozoa tail - Following spermiogenesis, the third region of the spermatozoa that has a head, neck and tail). The tail is also divided into 3 structural regions a middle piece, a principal piece and an end piece. In humans: the middle piece (5 µm long) is formed by axonema and dense fibres surrounded by mitochondria; the principal piece (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops; the final end piece (5 µm long) has an axonema surrounded by small amount of cytoplasm and plasma membrane.
  • spermatogonial stem cells - (SSCs) The spermatagonia cells located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (|Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
  • spermatozoon - singular form of of spermatozoa.
  • sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.
  • teratospermia - Clinical term for a spermatozoa with abnormal morphology (small, large, defects in the head, tail, and/or mid-piece) present in the semen or ejaculate.
  • testis cords - developmental structure that give rise to the adult seminiferous tubules, the other developmental region is the interstitium.
  • vasectomy - Clinical term for ligation of the scrotal portion of the ductus deferens.

See also: Spermatozoa Terms collapse table

Other Terms Lists  
Terms Lists: ART | Birth | Bone | Cardiovascular | Cell Division | Endocrine | Gastrointestinal | Genital | Genetic | Head | Hearing | Heart | Immune | Integumentary | Neonatal | Neural | Oocyte | Palate | Placenta | Radiation | Renal | Respiratory | Spermatozoa | Statistics | Tooth | Ultrasound | Vision | Historic | Drugs | Glossary
Genital Links: genital | Lecture - Medicine | Lecture - Science | Lecture Movie | Medicine - Practical | primordial germ cell | meiosis | endocrine gonad‎ | Genital Movies | genital abnormalities | Assisted Reproductive Technology | puberty | Category:Genital
Female | X | X inactivation | ovary | corpus luteum | oocyte | uterus | vagina | reproductive cycles | menstrual cycle | Category:Female
Male | Y | SRY | testis | spermatozoa | ductus deferens | penis | prostate | Category:Male
Historic Embryology - Genital 
General: 1901 Urinogenital Tract | 1902 The Uro-Genital System | 1904 Ovary and Testis | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1921 Urogenital Development | 1921 External Genital | 1942 Sex Cords | 1953 Germ Cells | Historic Embryology Papers | Historic Disclaimer
Female: 1904 Ovary and Testis | 1904 Hymen | 1912 Urinogenital Organ Development | 1914 External Genitalia | 1914 Female | 1921 External Genital | 1927 Female Foetus 15 cm | 1927 Vagina | 1932 Postnatal Ovary
Male: 1887-88 Testis | 1904 Ovary and Testis | 1904 Leydig Cells | 1906 Testis vascular | 1909 Prostate | 1912 Prostate | 1914 External Genitalia | 1915 Cowper’s and Bartholin’s Glands | 1920 Wolffian tubules | 1935 Prepuce | 1935 Wolffian Duct | 1942 Sex Cords | 1943 Testes Descent | Historic Embryology Papers | Historic Disclaimer

Other Species



Ductus Deferens Histology

Ductus deferens 01.jpgDuctus deferens 02.jpg

Prostate Histology

Prostate histology 01.jpg Prostate histology 02.jpg Prostate histology 03.jpg
Human prostate histology Corpora Amylacea Submucosal gland
(adult, low power overview) (adult, detail) (adult, high power detail)

Penis Histology


  • cortex - (Latin = rind, or bark) outer layer of an organ.
  • hilum - or hilus (Latin,= a trifle; depression in a seed) a depression at vascular entrance/exit of a gland or organ.
  • medulla - (Latin, medulla = pith, marrow) the inner portion of an organ, in contrast to cortex.
  • mucosa - (Latin, = mucous membrane) thin layer which lines body cavities and passages formed by epithelium and lamina propria.
  • parenchyma - (Greek," + enkeim = to pour in) the essential functional cells of an organ as opposed to its stroma.
  • serosa - (Latin, serum = whey; a pale fluid) a serous membrane lining body cavities.
  • stroma - (Greek, = a cover, table-cloth, bedding) term for the internal supporting frame-work of a tissue, or organ, as opposed to its parenchyma.
  • tunica albuginea - a dense, white, fibrous sheath enclosing a part or organ.

Links: Female | Ovary | Oocyte | Uterus | Vagina

Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary

Course Links

Moodle - ANAT2241 - 2019

Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary

Common Histology Stains  
Histology Stains - Common Stains and Their Reactions
mucins - light blue
pale pink
bright red
colloid - pinkmuscle - red
Iron Haematoxylin
Van Gieson
muscle: yellow/browncartilage - pink
Verhoeff's Elastin
elastic fibres - black
Silver Impregnation
reticular fibres - black
Methyl Green
dark green
light green
light green
Nuclear Fast Red
Gomori's Trichrome
keratin - redmuscle - purple/red
Heidenhain's Azan
deep blue
muscle - red
Osmium Tetroxide
myelin, lipids - black
Alcian Blue
mucins, - blue
Periodic acid-Schiff (PAS)
mucins, glycogen, glycocalyx - magenta
Phosphotungstic Acid-Hematoxylin (PTAH)
muscle bands - blue
Masson's Trichrome
cartilage, mucins - blue or green; muscle - red
Luxol Fast Blue
myelin - blue
Aldehyde Fuchsin
elastic fibres, mast cells - deep purple
Light Green
light green
dark blue
nucleic acids, Nissl granules - dark blue
Romanowsky (e.g. Leishman's)
acidophils - red, basophils - blue, azurophilic - purple
Aldehyde Pararosanilin elastic fibres - purple
Haematoxylin and Eosin
One of the most common staining techniques in pathology and histology. Acronym "H and E" stain. (H&E, HE).

  • Stains nuclei blue to dark-blue.
  • Stains the matrix of hyaline cartilage, myxomatous, and mucoid material pale blue.
  • Stains myelin weakly but is not noticeable if combined with eosin stain.
  • combined with Orange G (H & Or. G.) instead of eosin, specifically stains the granules of acidophilic cells of the adenohypophysis (anterior pituitary).
  • Stains cytoplasm pink to red; red blood cells are also bright red.
  • Common counterstain to hematoxylin.
  • Stain intensity varies with the formula as well as the fixative.

Practical Support

Pages can be accessed from any internet connected computer.

ANAT2241 Support Links: The Virtual Microscope | Covering and Lining Epithelia | Glandular Epithelia | CT Components | CT Types | Bone, Bone Formation and Joints | Muscle | Nervous | Blood | Eye | Cardiovascular | Respiratory | Integumentary | Gastrointestinal | Gastrointestinal Organs | Lymphatic and Immune | Endocrine | Urinary | Female Reproductive | Male Reproductive | Histology Stains | Histology Drawings | Practicals Health and Safety 2013 | Moodle - 2019

ANAT2241 This practical support page content is not part of the science practical class and provides only background information for student self-directed learning purposes.

Cite this page: Hill, M.A. (2024, April 16) Embryology ANAT2241 Male Reproductive System. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G