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33 Cards in this Set
- Front
- Back
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What are the three portions of the epididymis?
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Caput (head)
Corpus (body) Cauda (tail) |
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Where in the epididymis is sperm stored?
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Cauda
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What is the tunica albuginea?
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Thick capsule of connective tissue covering the testis
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What divides the testes into lobules?
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Connective tissue septa
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What is found in each lobule of the testes?
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1-4 seminiferous tubules
Interstitial tissue |
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Into what do seminiferous tubules collect?
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Rete testes
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What is the site of spermatogenesis?
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Seminiferous tubule
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How are seminiferous tubules arranged?
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Radially
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What are the two cell types found in the seminiferous tubules?
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Sertoli cells
Germ cells |
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What accounts for the specialized environment of the testes and why is this important?
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Sertoli support cells
35 degrees C This is important because mechanisms, such as RNA polymerases and other enzymes, only work in these specific conditions |
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In which direction to cells migrate as they mature in the seminiferous tubules?
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From the basement membrane towards the lumen
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Describe primordial germ cells in the embryonic stage
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Colonized at gonadal ridge
Committed to spermatogenic lineage Quiescent |
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Describe primordial germ cells at puberty
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Activated spermatogonia
Mitotic and meiotic divisions Post-meiotic production of sperm |
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What is spermiogenesis?
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The differentiation of early, round spermatid into spermatozoan
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What are the different stages of spermiogenesis?
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1. Elongation of the nucleus and cytoplasm
2. Formation of the flagellum 3. Condensation of the head and formation of the acrosome 4. Shedding of the cytoplasm and most organelles (ER, Golgi); redistribution of mitochondria into the mitochondrial sheath |
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What are the segments of the flagellum in the mature spermatozoan?
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Mid piece (mitochondria)
Principal piece End piece |
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What are the functions of Sertoli cells?
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- Structural support via ECM and cell junctions
- Assist germ cell movement and release - Nourish germ cells - Assists formation of blood-testes barrier |
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What are the functions of the blood-testes barrier?
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- Creates an environment for appropriate germ cell differentiation
- Protects autoantigenic germ cells from immune system - Protects germ cells from cytotoxic molecules |
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What are the components of the blood-testes barrier?
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- Anatomical (physical) barrier
- Physiological (permeability) barrier - Immunological barrier |
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What forms the anatomical barrier of the blood-testes barrier?
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Tight junctions between the basal portions of Sertoli cells
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How do sperm cells pass through the anatomical blood-testes barrier?
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Airlock mechanism
- Committed spermatogonia form above the first tight junction |
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What forms the physiological barrier of the blood-testes barrier?
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Transporters and carriers that regulate movement of substances between the blood and lumen
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What are the components of the immunological barrier of the blood-testes barrier?
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Local production of anti-inflammatory cytokines and immunosupressive factors
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Where are Leydig cells located and what is their purpose?
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Located in the interstitium of the testes
Produce testosterone |
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What structures are found in the interstitium between seminiferous tubules?
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Leydig cells
Vasculature Macrophages T-cells |
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What are key structural features of steroid secreting cells?
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Some rough ER
Extensive smooth ER Mitochondria with rounded cristae to cleave cholesterol side chains Lipid droplets to store cholesterol Coated pits for LDL uptake |
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What mechanisms drive sperm through the epididymis?
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Fluid flow
Peristalsis of myoid cells and smooth muscle |
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What kind of epithelium is found in the epididymis?
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Pseudostratified columnar epithelium
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What changes does the epididymis impose on sperm cells as they move through this structure?
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Sperm acquire the capacity for movement and fertility, though these remain dormant while in the epididymis
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How does the epididymis impose quiescence on traveling sperm?
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- Reduced pH (Cauda ~ 5.8)
- Reduced temperature - Low O2, high CO2 - High K+/Na+ ratio (highly depolarizing environment) |
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How does the epididymis impose maturation on sperm cells as they move through this structure?
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Epithelial secretory products adsorb to sperm
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