Reproductive Biotechnologies Andrology I The spermatogenesis Prof. Alberto Contri CHARACTERISTICS OF THE SPERMATOZOON 1) Aploid cell with high condensed DNA 2) Forward motility - flagellum 3) Enzymes for the oocyte penetration - acrosome 1
Definition DIFFERENTIATIVE PROCESS THAT PRODUCE SPERMATOZOA FROM SPERMATOGONIA DURING THIS PROCESS THE SPERM MODIFY LARGELY THE ASPECT AND LOST MOST OF THE INTRACYTOPLASMIC STRUCTURES - ONLY ESSENTIALS STRUCTURES Anatomic place of the spermatogenesis In the testis seminiferous tubule 3 functional compartments Interstitial Basal Adluminal 2
Main phases of the spermatogenesis DIFFERENTS PHASES FOR DIFFERENT CELLS INVOLVED Spermatogonia spermatocytogenesis Spermatocytes meiosis Spermatids spermiogenesis Spermatozoa 3
Spermatocytogenesis CHARACTERIZED BY MITOTIC DIVISIONS SPERMATOGONIA OF DIFFERENT TYPE SPERMATOGONIA FROM GONOCYTES (2 ND MONTH OF GESTATION) STEM CELL SPERMATOGONIA (SPERMATOGONIA A) COMMITTED SPERMATOGONIA (SPERMATOGONIA B) Spermatogonia A1 - Flattened nucleus - The spermatogenesis SPERMATOGONIA A Spermatogonia A2 - Large nucleus with euchromatin - Spermatogonia A3 - Larger nucleus with nucleolus/i) - Spermatogonia B1 - Large nucleus with chromatin flakes - SPERMATOGONIA B Spermatogonia B2 - Small nucleus with small ch. flakes - 4
Spermatocytogenesis TWO FUNCTIONS INITIATE SPERMATOGENESIS (BY COMMITTMENT OF THE SPERMATOGONIA) MAINTAIN A STEM CELL POPULATION Spermatogenesis is a continous process from the puberty to the dead or the disease Meiosis (only in gonads) FROM SPERMATOCYTES TO SPERMATIDS 1) HAPLOID 2) GENETIC MATERIAL EXCHANGE BETWEEN HOMOLOGOUS CHROMOSOMES 5
Meiosis (only in gonads) MITOSIS OF THE B 2 SPERMATOGONIA TO PRIMARY SPERMATOCYTES IN PRELEPTOTENE PHASE START OF THE MEIOSIS PRIMARY SPERMATOCYTES IN THE ADLUMINAL COMPARTMENT Meiosis (only in gonads) PRIMARY SPERMATOCYTE (DNA REPLICATION) Secondary spermatocyte (Haploid with double chrom) Secondary spermatocyte (Haploid with double chrom) Spermatid (Haploid) Spermatid (Haploid) Spermatid (Haploid) Spermatid (Haploid) Cells maintained intercellular bridges - interconnection 6
Spermiogenesis MORPHOLOGICAL DIFFERENTIATION OF SPERMATIDS SERMATIDS ROUND SMALL CELLS ROUND NUCLEUS NO DNA SYNTHESIS AND REPAIR FOUR DIFFERENT PHASES Spermiogenesis RELATED TO THE MATURATIVE CHANGES IN THE SPERMATIDS GOLGI CAP ELONGARION MATURATION 7
Spermiogenesis GOLGI PHASE Spermiogenesis PREDOMINANT GOLGI APPARATUS FORMATION OF SMALL VESICLES SMALL VESICLES FUSE IN A LARGE MIGRATION OF THE CENTRIOLES NEAR THE NUCLEAR ENVELOPE INDENTATION OF THE NUCLEAR ENVELOPE ARTICULAR FOSSA FORMATION OF AN FLAGELLAR CANAL - TUBULAR INFOLDING OF THE PM 8
CAP PHASE Spermiogenesis ACROSOME VESICLE FLATTENS SURROUND A SIDE OF THE NUCLEUS - CAP SPHERICAL NUCLEUS GOLGI APPARATUS REDUCES FLAGELLAR STRUCTURE OUT OF THE SHAPE OF SPERMATID ELONGATION PHASE Spermiogenesis NUCLEUS MOVE ON THE OUTSKIRT OF THE CELL DEVELOPMENT OF THE MANCHETTE TRANSIENT MICROTUBULAR STRUCTURE FROM THE CAUDAL REGION OF THE NUCLEUS TO THE FLAGELLUM ELONGATION OF THE NUCLEUS AND THE CYTOPLASMA 9
Spermiogenesis MATURATION PHASE CAUDAL MIGRATION OF THE MANCHETTE AND LOST WITH THE RESIDUAL BODY MOVEMENT OF THE ANNULUS IN THE FINAL POSITION MITOCHONDRIA FOLLOW THE ANNULUS FLAGELLATION SYNTHESIS OF THE PROTEINS OF THE FLAGELLUM Spermiogenesis SPERMIATION RELEASE OF INDIVIDUAL SPERMATOZOA IN THE LUMEN COUNTERPART OF THE OVULATION SMALL AMOUNT OF CYTOPLASMA REMAINED IN THE MIDPIECE ELIMINATION OF THE RESIDUAL BODY PHAGOCYTIZED BY SERTOLI CELLS 10
Spermiogenesis FROM EACH SPERMATOGONIUM HUNDREDS/THOUSANDS OF SPERMATOZOA SPERMATIDS/SPERMATOZOA WITH INTERCELLULAR BRIDGES UNTIL SPERMIATION REGULAR FEATURE OF THE CELL ASSOCIATIONS WITHIN THE SEMINUFEROUS TUBULE SPERMATOGENIC CYCLE Spermatogenic cycle CHANGES IN A GIVEN SECTION OF THE SEMINIFEROUS TUBULE BETWEEN TWO IDENTICAL DIFFERENTIATION STAGES CONVENTIONALLY, SPERMIATION IS USED AS REFERENCE POINT SPERMATOGENIC CYCLE IS THE COMPLEX OF THE EVENTS BETWEEN TWO CONSECUTIVE SPERMIATIONS 11
Spermatogenic cycle Spermatogenic cycle CELL ASSOCIATION IS REPEATED REGULARLY ALONG THE SEMINIFEROUS TUBULE - STAGE OF THE SPERMATOGENIC CYCLE STAGE CLASSIFIED ON PRESENCE OF SPECIFIC GERM CELLS (B-SPERMATOGONIA, PRIMARY SPERMATOCYTES, SECONDARY SPERMATOCYTES, SPERMATIDS) ASPECT OF THE SPERMATIDS (PHASE OF THE SPERMIOGENESIS) MOVE BY SPERMATOGENEIC WAVES ALONG THE SEMINIFEROUS TUBULE 12
Spermatogenic cycle LENGHT OF THE SPERMATOGENIC CYCLE TIME BETWEEN TWO CONSECUTIVE SPERMIATION IN NEAR TRACT OF THE SEMINIFEROUS TUBULE SPECIES-SPECIFIC DIFFERENCES SWINE HAMSTER MOUSE RAM HORSE/RABBIT RAT BULL DOG HUMAN 8.6 DAYS 8.7 DAYS 8.9 DAYS 10.4 D 12.2 D 12.9 D 13.5 D 13.6 D 16 D 13
Length of the Spermatogenesis RELATED TO THE COMMITTMENT OF THE A-SPERMATOGONIUM FOUND 4-5 GENERATIONS OF GERM CELLS FOUND IN THE SEMINIFEROUS CYCLE CONVENTIONALLY SPERMATOGENESIS IS 4.5 TIMES THE SPERMATOGENIC CYCLE LENGHT BOAR 39 DAYS RAM 47 DAYS STALLION 57 DAYS RAT 60 DAYS BULL AND DOG 61 DAYS HUMAN 74 DAYS Sperm excretion AFTER SPERMIATION IMMOTILE SPERMATOZOA IMMATURE SPERMATOZOA MOVE IN THE EXCURRENT DUCTS DILUTED IN THE SECRETION OF THE SERTOLI CELLS MOVE BY PERISTALTIC CONTRATION OF SMOOTH MUSCULATURE 14
Epididymal transit and maturation IN SUMMARY CONCENTRATE (10 5 -FOLD INCREASE) MATURATE TRANSPORT STORE Epididymal transit and maturation ACTION BY MODIFY THE MILIEU PRESENCE OF A BLOOD-EPIDIDYMIS BARRIER METABOLIC MODIFICATIONS INCREASE IN INTRACELLULAR AMP-C INCREASE IN DISULFIDE BOND OF PROTAMINES ACQUIRING SPERM MOTILITY TRANSLOCATION AND LOST OF THE CYTOPLASMIC DROPLET 15
Sperm transport EJACULATION EXPULSION OF SPERMATOZOA AND SEMINAL PLASMA OUTSIDE CONTROLLED BY THE AUTONOMIC NERVOUS SYSTEM PERISTALTIC CONTRATION OF THE SMOOTH MUSCULATURE OF THE URETHRA Sperm transport DEPOSITION OF SEMEN IN THE GENITAL TRACT DIFFERENT AMONG SPECIES INTRAUTERINE: SWINE, RODENTS, IN PART HORSE INTRAVAGINAL: IN RUMINANTS, HUMAN, RABBIT, CAT, IN PART DOG 16
Sperm transport TWO DIFFERENT TYPE ACTIVE: MOTILITY OF SPEMRATOZOA PASSIVE: UTERINE CONTRACTION (ANS; OXYTOCIN, PGFS) Sperm transport SELECTION OF SPERMATOZOA CERVICAL AND UTERO-TUBAL JUNCTION BARRIERS CERVICAL MUCOUS DIFFERENT FLUIDITY RELATED TO ENDOCRINE PATTERN ESTROGENS INCREASE FUIDITY LONGITUDINAL DISPOSITION OF THE PROTEINS 17
Sperm transport CERVIX AND UTERO-TUBAL JUNCTION ONLY PASSIVE BARRIER? EVIDENCE OF INCREASED SPERM WITH NORMAL SPERM DNA IN THE OVIDUCT Sperm transport COLONIZATION OF THE FEMALE REPRODUCTIVE TRACT DIFFERENT PHASES: I) PRIMARY OR RAPID (SECONDS OR MINUTES) RELATED TO THE UTERINE PERISTALTIC PUMP II) SECONDARY OR RETARDED (HOURS) INTERACTION WITH THE OVIDUCTAL CELLS AND SPERMATOZOA CREATION OF OVIDUCTAL SPERM RESERVOIR RELEASE COORDINATED WITH OVULATION 18