University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2022
Views:

107

Pages:

82
Author:

Kundulu8mbj

Male reproductive system: Part 1 Spermatogenesis Part 1 Spermatogenesis Objectives • Identify the endocrine and exocrine subdivisions of the testes? • Distinguish the cells of the spermatogenic cell lineage. • Identify and distinguish among epididymis, vas deferens, urethra, seminal vesicles and the prostate gland. • Describe the structure of the penis and indicate how it becomes tumescent. Human sperm in smear 1. Spermatozoon Human epididymal spermatozoa Human ejaculated spermatozoon horse The microtubular structure of spermatozoan flagellum is composed of microtubule axonemes 9+2 structure: 2 singlet microtubules, surrounded by 9 doublet microtubules with dynein arms. DYNEIN ARMS are a PAIRED LATERAL APPENDAGES That are PROTEIN with ATPase ACTIVITY FOR CILIARY AND FLAGELLAR MOTILITY. . Fetal testis Interstitial cells Seminiferous tubules Pre-Sertoli cells Gonocytes Capsule Human testis capsule and parenchyma Seminiferous tubules Veins Leydig cells Arteries Lymph vessels There are major blood vessels within the capsule (tunica albuginea), and these are related to cooling the testis. Nerves Lymph vessels UT 166 Mesothelium Testis capsule Artery Human testis capsule 1. Testis capsule Vein Vein Artery Blood supply around seminiferous tubules SEMINIFEROUS TUBULES COMPOSED OF: MYOID CELLS SERTOLI CELLS GERM CELLS SPERMATOGONIA, SPERMATOCYTES, SPERMATIDS human SEMINIFEROUS TUBULES COMPOSED OF: MYOID CELLS SERTOLI CELLS GERM CELLS SPERMATOGONIA, SPERMATOCYTES, SPERMATIDS human Meiotic activity larger secondary spermatocytes and smaller Golgi phase spermatids human testis metaphase figures in meiosis secondary spermatocytes Pachytene primary spermatocytes Letotene primary spermatocytes To find secondary spermatocytes, one needs to find a tubule in stage VI of the spermatogenic cycle with metaphase figures in meiosis and no (almost no) pachytene primary spermatocytes. The pachytene primary spermatocytes are the immediate precursor to secondary spermatocytes. 19680 Monkey seminiferous epithelium 1. Spermatogonia 2. Myoid cell 3. Sertoli cell 4. Fibroblast Leydig cells 19680 Monkey seminiferous epithelium 1. Spermatogonia 2. Myoid cell 3. Sertoli cell 4. Fibroblast Leydig cells 19680 Monkey seminiferous epithelium 1. Spermatogonia 2. Myoid cell 3. Sertoli cell 4. Fibroblast Leydig cells 19680 Monkey seminiferous epithelium 1. Spermatogonia 2. Myoid cell 3. Sertoli cell 4. Fibroblast Leydig cells 19680 Monkey seminiferous epithelium 1. Spermatogonia 2. Myoid cell 3. Sertoli cell 4. Fibroblast Leydig cells Testis Leydig (interstitial) cells Tunica albuginea Residual bodies Basement membrane Myoid cell Sertoli cells Seminiferous tubules Leydig (interstitial) cells Testis Tunica albuginea Residual bodies Basement membrane Myoid cell Sertoli cells Seminiferous tubules Testis Dividing spermatogonia (mitotic division) Spermatozoa Primary spermatocytes Early spermatids Myoid cell Late spermatids Sertoli cell Testis Late spermatids Myoid cell Dividing spermatogonia (mitotic division) Spermatogonia Primary spermatocytes Early spermatids Sertoli cells Leydig cells Spermatogenesis SPERMATIDS SPERMATOGONIA SPERMATOCYTES Spermatogenesis SPERMATIDS SPERMATOGONIA SPERMATOCYTES Spermatogenesis SPERMATIDS SPERMATOGONIA SPERMATOCYTES The three germ cell types divide spermatogenesis into three major events SPERMATOCYTOGENESIS MEIOSIS SPERMIOGENESIS SPERMATOCYTOGENESIS HAS TWO FUNCTIONS PRODUCES PRIMARY SPERMATOCYTES WHICH RESULT IN THE PRODUCTION OF SPERM 47 DAYS LATER PRODUCES STEM CELLS WHICH INSURE A CONSTANT SUPPLY OF GERM-CELL PRECURSORS THROUGHOUT LIFE MEIOSIS (ONLY IN SPERMATOGENESIS AND OOGENESIS) EXCHANGE OF GENETIC MATERIAL IN HOMOLOGOUS CHROMOSOMES (LEPTOTENE, ZYGOTENE, PACHYTENE, AND DIPLOTENE STEPS OF DEVELOPMENT) PRODUCES HAPLOID CONDITION OF GAMETES MEIOSIS All images Copyright McGraw-Hill Companies A primary spermatocyte contains 46 chromosomes, the diploid number. However, the secondary spermatocyte contains 23 chromosomes although they are duplicated. A spermatid contains 23 chromosomes, the haploid number. High voltage EM of horse seminiferous tubules EM 19a 1. Sertoli cell nucleus 2. Mitochondrion 3. Spermatogonium 4. Spermatids 5. Primary spermatocyte Golgi phase spermatids SPERMIOGENESIS (DIFFERENTIATION OF SPERMATIDS WITH ROUND NUCLEI TO THOSE CHARACTERISTIC OF SPERMATOZOA) ACROSOME FROM GOLGI NUCLEAR CONDENSATION AND ELONGATION FLAGELLUM SHEDDING EXCESS CYTOPLASM SPERMIOGENESIS in the horse Horse spermatids horse Acrosome reacted Intact Cell-membrane intact and acrosome reacted The formation and function at the acrosome. horse spermatozoa 1. Golgi phase Small proacrosomal vesicles from Golgi coalesce as a single membrane-limited acrosomal cap close to one end of the nucleus. 2. Cap phase The acrosomal cap spreads over about half of the condensing nucleus. 3. Acrosome phase The head of the developing spermatid, containing the acrosome and the condensing nucleus, remains embedded in the recesses of the Sertoli cell while the flagellum continues to grow. 4. Maturation phase Unneeded cytoplasm is shed, and spermatid is released into lumen with acrosome. SPERMIOGENESIS Function in the The horse acrosome is a specialized lysosome containing hydrolytic enzymes (mainly hyaluronidase and acrosin). These enzymes are released when a spermatozoon encounters an oocyte and the acrosomal membrane fuses with the sperm’s plasma membrane. This process, the acrosomal reaction, is one of the first steps in fertilization. The enzymes dissociate cells of the corona radiata and digest the zona pellucida, both structures that surround the egg. horse Slightly modified text From Copyright McGraw-Hill Companies Golgi phase Golgi phase Cap phase Golgi phase Cap phase Elongation phase Golgi phase Cap phase Elongation phase Maturation phase Maturation phase EMs 32, 8, & 24: Developing spermatids Golgi Developing acrosome Spermatid nucleus Manchette, transient organelle Human Residual bodies Spermatids and Spermatozoa Testes Human – infertile man SERTOLI CELLS PROVIDE SUPPORT AND NUTRITION TO DEVELOPING GERM CELLS RELEASE SPERMATIDS AS SPERM PHAGOCYTIZE DEGENERATING GERM CELLS AND RESIDUAL BODIES SECRETE: A. ANDROGEN BINDING PROTEIN B. CALMODULIN C. PLASMINOGEN ACTIVATOR D. INHIBIN BLOOD TESTIS BARRIER SERTOLI CELLS PROVIDE SUPPORT AND NUTRITION TO DEVELOPING GERM CELLS RELEASE SPERMATIDS AS SPERM PHAGOCYTIZE DEGENERATING GERM CELLS AND RESIDUAL BODIES SECRETE: A. ANDROGEN BINDING PROTEIN B. CALMODULIN C. PLASMINOGEN ACTIVATOR D. INHIBIN BLOOD TESTIS BARRIER Sertoli cells contribute to spermiogenesis through their nurse-cell function of providing physically and metabolically support to developing germ cells and the specific release of spermatids and phagocytosis of residual bodies. EM 21 Sertoli cell cytoplasm UT EM 19c; Sertoli cell; 13 300x 1. Golgi 2. Heterophagic vacuole 3. Lipid droplet 4. Microtubule 5. Nuclear pores (cross-section) 6. Sertoli cell 7. Synaptoneural complex UT EM 19c Six stages of the spermatogenic cycle in humans STAGES of the Spermatogenic cycle in humans UT 165 human testis spherical, elongating (condensing), and elongated (maturation phase) spermatids III human testis spherical, elongating (condensing), and elongated (maturation phase) spermatids III IV human testis spherical, elongating (condensing), and elongated (maturation phase) spermatids III IV V human testis spherical, elongating (condensing), and elongated (maturation phase) spermatids III IV VI V Human spermatogenesis: path followed through spermatocytogenesis, meiosis, and spermiogenesis as a given cell travels through five spermatogenic cycles Blood testis barrier OCCLUDING JUNCTIONS BETWEEN SERTOLI CELLS BLOOD-TESTIS OCCLUDING JUNCTIONS BETWEEN SERTOLI CELLS IN SEMINIFEROUS TUBULES Human spermatogenesis: path followed by given cell Basal compartment with spermatocytogenesis BLOOD TESTIS BARRIER Adluminal compartment with meiosis and spermiogenesis INTERCELLULAR BRIDGES CAUSE - INCOMPLEE CYTOKINESIS FOUND AMONG CLUSTERS OF SPERMATOGONIA, SPERMATOCYTES, OR SPERMATIDS (never between cells in different steps of development, e.g., never between SPERMATOGONIA and SPERMATOCYTES) POSSIBLE FUNCTIONS MEDIATE BOTH DIFFERENTIATION AND DEGENERATION OF SPERMATOGONIA MAINTAIN SYNCHRONOUS DEVELOPMENT INTERCELLULAR BRIDGES OCCLUDING JUNCTIONS BETWEEN SERTOLI CELLS are still above but now appear below the zygotene spermatocytes 165 Interstitium (monkey) 1. Leydig cell 2. Endothelial cell of lymph vessel 3. Blood vessel 4. Fibroblast 291 165 Interstitium (monkey) 1. Leydig cell 2. Endothelial cell of lymph vessel 3. Blood vessel 4. Fibroblast 291 165 Interstitium (monkey) 1. Leydig cell 2. Endothelial cell of lymph vessel 3. Blood vessel 4. Fibroblast 291 Horse Leydig cells: EM 20 1. Smooth endoplasmic reticulum 2. Gap junction 3. Nucleus of leydig cell 4. Tubular cristae of a mitochondion horse HORMONAL CONTROL OF SPERMATOGENESIS HORMONE CELL STIMULATED IN SPERMATOGENESIS FSH SERTOLI CELLS SPERMATOCYTOGENESIS SPERMIATION LH LEYDIG CELLS (TESTOSTERONE) MEIOSIS Leydig cells Leydig cells ??? Nerve Odd : What appears to be Leydig cells inside the nerve in the human testis. Leydig cells Leydig cells ??? Nerve Odd : What appears to be Leydig cells inside the nerve in the human testis. Summary of Male reproductive system: Part 1 Spermatogenesis

Male Reproductive System Part 1 Spermatogenesis

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