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Home , Testicle, Tubuli seminiferi recti

Histology of the ,

Dr. Zsuzsanna Tóth Semmelweis University Department of , Histology and Embryology The structure of the testis

lobule GE Lu

interstitium

Trichrom staining Seminiferous convoluted : • germinal (spermatogenic) ; Sertoli cells, developing germinal cells • basal lamina • myoid cells • connective tissue wall H & E

Lu GE Sp

GE Leydig

Myoid cells Intersitial Leydig cells produce

• Form groups (10-20 cells) • producing cell characteristics: polygonal shape, acidophylic cytoplasm, round nucleus with nucleolus, abundant SER, lipid dropplets in the cytoplasm • Cytoplasmatic hexagonal prisms: Reinke crystalloids • The number of the Leydig cells decreases in erderly • Regulation by the , Luteinizing- (LH) – stimulatory The role of testosterone in

SRY gene: -determining region of the ) Types of cell division

redukció Generation of genetic diversity in I.

• Genetic variation:  homologous recombination  random segregation of the chromosomes Meiosis II is similar to mitosis

• Meiosis II : starts without DNA replication • Produces four haploid daughter cells: • male: 4 , 22+X or 22+Y chromosome sets • female: 1 ovum and 3 polar bodies (22+X) Spermatogenesis

• Spermatogonia are of endodermal (4th week, yolk sac) origin

• Spermatogenic syntitium: sister cells are connected by bridges of cytoplasm (intense cell-cell communication)

64 • The grouped cells develop days synchronously

• Meiosis starts at the and then it takes place continously

• Follicle stimulating hormone (FSH) have stimulatory effect The Supporting and nutrient function

Cheng C Y , and Mruk D D Physiol Rev 2002;82:825-874 • Columnar epithelial cells, develop from the epithelial

AdluminalAdluminalis • Span from the basement membrane to the lumen compartmentcompartment • Ovoid, triangular cell nucleus, pale nuclear staining, the nucleolus is visible • Intercellular pockets - nursery for the proliferating germinal cells Blood Vér- testis-here barriergát • Tight junctions between Sertoli cells: basal and adluminal compartments: Blood testis barrier( avascular parenchyma, protection against ) • Phagocytic activity

BasalisBasal • Secrete testicular fluid, -binding protein, inhibin compartment compartment • Anti-mullerian hormone secretion during embryonic development The blood-testis barrier defines the adluminal and basal compartments

Cheng C Y , and Mruk D D Physiol Rev 2002;82:825-874

©2002 by American Physiological Society Spermatogenesis waves move in spirals

Groupings of various generations in a cross-section:

spermatogonia

Morphology of developing germinal cells

Spermatogonia: are in contact with the basal lamina, have medium sized, round nucleus Primary spermatocytes (MI): are the largest cells, with large round nucleus, visible chromosomes Secondary spermatocytes (MII): are smaller, have very short lifetime, rarely seen Round and elongated spermatides: are small with condensed (dark) nuclei in the innermost layer Spermatozoa: head and tail, are seen in the lumen Sertoli cells: large cells, ovoid, pale nucleus with nucleolus

Spermiogenesis: maturation of the spermatids into spermatozoa

• Development of motility: formation

• Size reduction:

 Nuclear condensation: the DNA is tightly packed, most of the RNA is eliminated

 Reduction of cytoplasmatic mass

• Formation of the acrosome: a cell organelle, with enzymes necessary to fertilization of the ovum

• Energy: many mitochondria (ATP) The structure of the cell

human spermatozoa (~60 µm) Acrosome (contains enzymes necessary for penetration into the ovum)

Head nucleus cell membrane mitochondria Neck centrioles axoneme Mid (connecting) microtubule complex, outer dense fibres dense fibers piece spiral mitochondrial complex cell membrane

longitudinal column outer dense axial filament of the fibrous sheath Tail fibres circumferential axoneme (9+2 pairs of MT) Principal ribs of the FS cell longitudinal column piece microtubules (MT), membrane of the fibrous sheath dense fibres

axoneme (9 pairs of outer microtubules) cell membrane axoneme (central pair of inner microtubules) End piece microtubules cell membrane

Motility is only activated during . Step by step

1. Golgi phase: proacrosomal granules pinch off from Golgi; primitive flagellum formation (axoname) starts from the periferal centriole at the opposite pole of the cell. 2. Cap phase: granules fuse (PAS+) and form the acrosomal cap that associates with the rostral nuclear envelope, chromatin condensation starts, the flagellum grows 3. Acrosomal phase: further chromatin condensation, excentric nucleus with closly adhered acrosome, elongation, the peripheral centriole forms 9 dense fibres and the fibrous sheeths around the axoname. Spiral mitochondria form. 4. Maturation phase (spermiation): formation of the residual body (RB, excess cytoplasm) – Sertoli cells phagocyte the RBs, cytoplasmatic bridges disappear, free sperms enter the lumen Straight tubules ()

• radiate from the , within the septa • transfer speratozoa from the seminiferous tubules toward the • epithelium: proximally single columnar (Sertoli) cells, distally cuboidal cells Rete testis

• labyrinth like network of anastomosing channels embedded in the fibrous tissue of the mediastinum • flattened squamous, or low cuboidal epithelium lining, microvilli • mixes, transports and modifies the luminar fluid • drains into the efferent ductules Regulation of the testicular hormone production

Influencing factors:

• temperature • stress • inflammation () • ischaemia • radiation • cytotoxic drugs (chemotherapy)