Male Reproductive System Histology Lecture (Dr. Cole) Flashcards
Functions
- Production and storage of SPERMATOZOA
- Synthesis and Secretion of Male Sex Hormones (ANDROGENS)
- TESTES: Production and Synthesis
- EFFERENT DUCT SYSTEM:
a) Epididymis
b) Ductus Deferens
c) Ejaculatory Duct
d) Urethra - Three Accessory Glands
1) Seminal Vesicle
2) Prostate
3) Bulbourethral Gland - Penis
Seminiferous Tubules
- 1 to 4 in EACH LOBULE
- 40 to 70 cm in Length
- Walls composed of THREE LAYERS
1) TUNICA PROPRIA
2) BASAL LAMINA
3) SEMINIFEROUS EPITHELIUM
Sertoli (Supporting) Cells
- Tall, branched Columnar Cells that rest on Basement Membrane
- PALE OVAL Nucleus with a PROMINENT NUCLEUS
- Protect developing Spermatids
- Respond to FSH
- Margins poorly defined yet bound TIGHTL (Occluding Junctions)
- Forms a continuous sheaths round the Lumen
- BLOOD-TESTIS BARRIER!!!!!!!
Function of Sertoli Cells
1) PHYSICAL SUPPORT: Extensive Cytoplasmic Ramifications of Sertoli Cells
2) PHAGOCYTOSIS of Residual Bodies
3) SECRETION: Fluid for Sperm Transport, Androgen- Binding Protein (ABP), Inhibit (Negative Feedback on GnRH and FSH Secretion), Antimullerian Hormone and Activin (Positive Feedback on FSH Secretion)
4) NUTRITIONAL REGULATION: Isolation of Developing SPERMATOZOA from Blood, Spermatogenic Cells depend upon Sertoli Cells for exchange of Nutrients
Protection: Blood Testis Barrier
- Sexual Maturity occurs long after development of IMMUNOCOMPETENCE
- Prevent developing SPERMATOZOA from being recognized as Foering (Sperm Specific Proteins) and provoking a Immunological Response
- Continuous Belt of occluding Junctions joining lateral surfaces of ADJACENT Sertoli Cells
- Separates SEMINFEROUS TUBULE into TWO Functional Compartments
Sertoli Cell Only Syndrome (SCOS)
- GERMINAL CELL APLASIA or DELL CASTILE SYNDROME
- Spermatogenic Cells ABSENT!!!!!
- LEYDIG Cells: REINKE CRYSTALLOIDS (Also seen in LEYDIG Cell TUMORS)!!!!!!!!
- PERMANENT and IRREVERSIBLE AZOOSPERMIA
- Congenital or Acquired (Radiation, Chemo, Trauma)
Spermatogenesis
- Multistep Differentiation to produce MATURE SPERMATOZOA
Three Phases:
1) Spermatocytogenesis
2) Meiosis
3) Spermiogenesis
Division of Spermatogonia to form Primary Spermatocytes via MITOSIS
- 3 groups based on Nuclear Morphology:
1) A dark (Ad)
2) A pale (Ap)
3) B - Stem Cells: Ad, undergo Mitosis to produce Ad and Ap. Ap divide to form Type B
- B undergo further Mitosis to form Primary Spermatocytes
- Resistant to Radiation and CA Chemotherapy
Spermatogenesis: Meiosis
- SECOND STAGE or Spermatogenesis
- PRIMARY SPERMATOCYTES: DIPLOID for Chromosome Number but TETRAPLOID for DNA (46, 4n)!!!!!!!!!!!!!!!!!!
- Several Stages (5) Based on Changing patterns of Nuclear Chromatin
- Ends with FIRST Meiotic Division with formation of SECONDARY SPERMATOCYTES!!!!!!
Meiosis I: Prophase
- Takes about 22 Days
- Most PRIMARY SPERMATOCYTES are seen in PROPHASE!!!!!
- Largest Spermatogenic Cells
- Characterized by CHROMOSOMES in Various Stages of Coiling (Nuclear Morphology will vary)
Secondary Spermatocytes
- Primary Spermatocytes UNDERGO the FIRST Meiotic Divison to form SECONDARY SPERMATOCYTES
- Closer to the Lumen
- Smaller in Size (HAPLOID for CHROMOSOME Number but DIPLOID for DNA)
Spermatids
- Products of Second Meiotic Division
- HAPLOID for BOTH Chromosome Number (23) and DNA
- SMALL CELSL WITH HERTEROCHROMATIC NUCLEI!!!!!!
- LOCATED CLOSER TO THE LUMEN!!!!!!
- ROUND: EALRY SPERMATIDS!!!!!
- Sz: Spermatids or LATE Spermatids
Spermatozoa (Sz)
- LOCATED IN THE LUMEN OF SEMINIFEROUS TUBULES
- Final Product of SPermiogenesis
- Dark, Flattened Nuclei
- Have long Flagella
- Haploid for BOTH CHROMOSOME Number (23, n) and DNA
- Also called SPERMTIDS
Review of Spermatid formation
1) Germ cells that are the Origin of Sperm cells are DIPLOID CELLS (Containing 46 Chromosomes, or 23 pairs) called SPERMATOGONIA. Mitotic Divisions of these cells produce a NEW GERM CELL and a COMMITTED CELL. The Committed cell is a PRIMARY SPERMATOCYTE
2) The FIRST meiotic Division begins in the DIPLOID Primary Spermatocytes. The HAPLOID CELLS (Containing 23 Chromosomes Only) Produced by the FIRST Meiotic Division are called SECONDARY SPERMATOCYTES
3) The SECOND Meiotic Division originates with the SECONDARY SPERMATOCYTES and produces SPERMATIDS
4) The process of SPERMATOGENESIS begins with Spermatids and results in Morphological changes needed to form Sperm that will be MOTILE
Spermatogenesis: 4 Major Events
1) Development of the FLAGELLUM
2) Development of the ACROSOME (4 Phases)
3) Development of the MACHETE
4) NUCLEAR CONDENSATION (Protamines)
Cap Phase
- SPECIALIZED LYSOSOME
- Contains a variety of HYDROLYTIC ENZYMES
- Aid in PENETRATION the OVUM during Fertilization
Acrosomal Phase
- FLAGELLUM emerges from Axonemal Complex of one Centriole to FORM TAIL
- The other Centriole forms FIBROUS RINGS (9) that surround AXONEME
- Band of MICROTUBULES surrounds Nucleus (MANCHESTER)
Maturation Phase
- Nucleus flattens and ELONGATES
- Mt MIGRATE IN
- Residual body PHAGOCYTOZED
- Sperm released into the Lumen
***Nuclear Shaping and Condensation
*** Somatic HISTONES replaced by Sperm Specific Histones (PROTAMINES)
Primary Ciliar Dyskinesia or Immotile Cilia Syndrome
KARTAGENER’S SYNDROME:
- NO DYNEIN ARMS!!!!!!!!!
Semen
- 20 to 40 Million/ mL
- OLIOSPERMIA
Leydig Cells
- Occur in Clusters between the Tubules
- Secrete TESTOSTERONE on Stimulation by LH!!!!
Clinical Considerations
- Temp: Maintain at 34-35 Degrees Celsius
- CRYPTOCHIDISM: UNDESCENDED Testes. Issued for FERTILITY and Increased risk of TESTICULAR Cancer!!!!!!!
- MUMPS: 20 to 30% Incidence of ACUTE ORCHITIS
- TORSION: Cut off ARTERIAL SUPPLY ad VENOUS DRAINAGE. Untreated leads to HEMORRHAGIC INFARCTION and NECROSIS of Testes
- VARICOCELE: Dilation of Veins in Spermatic Cord. DECREASE in Sperm Production
Genital Duct System
- Sperm MATURAITON Pathway
- Continuous with SEMINFEROUS TUBULES
- Extends from Straight Tubules/ RETE TESTIS to the Urethra
- Intratesticular and Excretory portions
- Important in Maturation, Storage, and Transport of SPERMATOZOA
- TESTOSTERONE necessary for Normal Function
Flow of Sperm out of the Penis
1) STRAIGHT TUBULES/ RETE TESTIS:
- Low CUBOIDAL Cells, Fibroblasts and Myoid for PERISTALSIS
2) EFFERENT DUCTULES:
- Mixed Epithelium of TALL CILIATED Columnar (Propel Sperm) and Low Cuboidal. Microvilli Principal Cells (Absorb Testicular Fluid)
3) EPIDIDYMIS:
- PSEUDOSTRATIFIED CILIATED COLUMNAR Epithelium and Principal Cells/ Stereocilia; Sheath of Circular Smooth Muscle.
- PERISTALTIC Contractions PROPEL Sperm towards DUCTUS DEFERENS
