Spermatogenisis

Male Reproductive System Testes Genital Ducts –Epididymis –Ductus deferens –Ejaculatory duct –Urethra Accessory glands –Seminal vesicle –Prostate –Bulbourethral gland Penis

Spermatogenesis At puberty, spermatogonia (types A & B) divide by mitosis Type A spermatogonia are the stem cells Type B spermatogonia become 1˚ spermatocytes that undergo 1st meiotic division forming 2˚ spermatocytes Since prophase of the first meiotic division takes approx. 22 days, most cells in your H&E sections will be in this mode ( primary spermatocytes ) 2˚ spermatocytes undergo 2nd meiotic division forming spermatids Spermatids shed most of cytoplasm and develop into spermatozoa with long flagella

Spermatogenesis

Coordination of Spermatogenesis All sperm cells originate from a basally derived spermagonium. They remain attached by a series of cytoplasmic bridges until mature spermatids form The cycle of the seminiferous epithelium refers to the wave-like non- synchronous pattern of development in different regions of the seminiferous tubules

Golgi phase of Spermiogenesis The acrosomal granule contained in the acrosomal vesicle that adheres to nuclear envelope of spermatid is formed from the Golgi apparatus Centrioles migrate away from nucleus toward the posterior pole and begin to form axoneme of flagella Flagellar axoneme elongates from one centriole as the other centrioles migrates back toward nucleus spinning out the components of the axoneme ( microtubules )

Acrosomal Phase of Spermiogenesis Acrosome formed by the speading of acrosomal vesicle across anterior half of nucleus –contains hydrolytic trypsin-like enzymes that dissociate the corona radiata and digests the zona pellucida during fertilization ( Acrosomal Reaction ) Spermatids are oriented toward the base of the seminferoous tubule and elongate. One centiole grows forming the flgellum, the other forms a collar around the base of the flagellum Microchondria aggregate around proximal region of flagella forming the mid-piece for spermatozoa movement

IMMOLITE CILIA ( KARTAGENER ) SYNDROME CHARACTERIZED BY IMMOTILE SPERM THEREFORE INFERTILITY LACK OF DYNEIN ( ATP ACTIVATED ) AND OTHER PROTIENS NEEDED FOR MOTILITY THIS COINCIDES WITH CHRONIC RESPIRATORY INFECTIONS SINCE A SIMILAR DEFICIENCY EXIST IN THE AXONEME OF PSEUDOSTRATIFIED COLUMNAR EPITHELIUM IN THE RESPIRATORY PASSAGES

Maturation phase of Spermiogenesis Cytoplasm within and between (intercellular bridges) the spermatids is lost and phagocytized by the Sertoli cells Resultant cell lineage remains attached by cytoplasmic bridges for communication. The communications are lost when this residual cytoplasm is phagocytized Spermatazoa are released tail first into seminiferous tubules; they are non-motile until they enter epididymis. This whole process occurs in a non-synchronous wave like motion

Spermiogenesis

–Nucleus composed of condensed chromatin & a few areas of dispersed chromatin (nuclear vacuoles) –Acosomal cap contains hyaluronidase, neuraminidase acid phosphatase and a protease enzymes that degrade corona radiata and the zona pellucida of egg during fertilization Spermatozoa Head

Spermatozoa Neck –A short region that connects head to tail –Axoneme has arrangement of microtubules –Axoneme surrounded by condensed fibrous rings –Region contains the most cytoplasm

Spermatozoa Tail Middle piece –Axoneme surrounded by 9 parallel coarse fibrils –Spirally arranged mictochondria surround fibrils and axoneme –Thickening of plasma membrane (annulus) keeps mitochondria in middle piece

Spermatozoa Tail Principle piece –Comprises most of tail, approximately 50um –Consists of axoneme & the 9 fibril core –Circular fibrous two rib like bundles surround the core –Two of the longitudinal fibrils fuse with these ribs and divide this region in half longitudinally End piece –Consists of axoneme only

Semen Consists of spermatozoa and seminal fluid, which contains fructose & citrate to provide energy for motility Spermatazoa do not become “capable of fertilization” until activiated in female genital tract, a process known as full capacitation Also contains desquamated cells, prostatic concretions and other urinary debris