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19 Cards in this Set
- Front
- Back
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Describe the function and organization of the testes
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1. Function
a. Spermatogenic-production of spermatozoa b. Endocrine-production of testosterone 2. Organization a. Testicular capsule-capsule undergoes periodic contraction (regulates size of testes) 1) tunica vaginalis-outer layer of mesothelium. 2) tunica albuginea-middle layer; dense fibroelastic tissue w/some smooth muscle cells 3) tunica vasculosa-inner vascular layer b. lobules-250/testes 1) T. albuginea is thickened posteriorly and projects into testes as Mediastinum Testes 2) Thin fibrous partitions radiate from mediastinum testes to capsule (forms testicular lobules); deficiencies exist in septa (thus lobules communicate) |
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Describe seminiferous tubules
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a. 2-4 tubules/lobule embedded in loose CT containing vessels, nerves, and cells (macrophages, fibroblasts, smooth muscle cells, Leydig cells)
b. lined by germinal epithelium (modified stratified epithelium) which rests on basal lamina c. Epithelium-2 cell types 1) spermatogenic (spermatogonia, spermatocytes, spermatids) 2) Sertoli cells |
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Describe the interstitial cells of Leydig
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a. contained in CT surrounding seminiferous tubules; large cells; nucleus contains coarse chromatin granules & distinct nucleolus
b. produces testosterone that controls: 1. appearance of secondary sex characteristics 2. sex impulse 3. development of genital ducts and accessory glands 4. spermatogenesis |
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Describe the vessels and nerves of the testes
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a. branches from testicular A pierce tunica albuginea at mediastinum & pass to t. vasculosa; smaller branches follow septa to parenchyma
b. venous drainage through mediastinum testes c. nerves accompany major vessels & form fine plexuses around smaller vessels |
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Describe spermatogenesis as it relates to seminiferous tubules and epithelium
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a. seminiferous tubule
1) site of spermatogenesis 2) complex stratified epithelium 3) well-defined basal lamina around periphery 4) tunic of fibrous CT a) myoid cells in C.T. b) membrane jnxs b/t myoid cells hinder but don't prevent passage of macromolecules b. epithelium 1) Sertoli cells 2) spermatogenic cells (4-8 layers) a) spermatogonia b) primary and secondary spermatocytes c) spermatids d) spermatozoa |
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Describe the stages of spermatogenesis
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1) spermatocytogenesis-spermatogonia divide several times, giving rise to spermatocytes
2) meiosis-spermatocytes undergo 2 successive divisions w/ reduction by 1/2 number of chromosomes & DNA to yield spermatids 3) spermiogenesis-spermatids differentiate into spermatozoa |
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Describe spermatocytogenesis and meiosis
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1) spermatogonia
2) primary spermatocytes a) largest cells of lineage b) soon after developed, enters an extended prophase c) undergoes diakinesis (final stage of prophase) d) enters metaphase, anaphase, telophase e) progeny yielded are known as secondary spermatocytes 3) secondary spermatocytes a) difficult to observe b) remains in interphase briefly-->enters second meiotic division to form spermatids 4) spermatids a) small size, condensed chromatin b) located towards lumen of tubules c) undergoes process of differentiation into spermatozoa through process of spermiogenesis |
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Describe spermiogenesis
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transformation of spermatids into spermatozoa
stages: a) formation of proacrosomal granules; fuse into single acrosomal granule called acrosomal vesicle b) acrosomal vesicle attaches to nuclear membrane; forms head cap (acrosome) note: acrosome-rich in carbohydrate, hyaluronidase, acid phosphatase (specialized lysosome); important in penetration of secondary oocyte (digestion of zona pellucida) c) tail formation-centrioles become positioned at side of nucleus opposite acrosome d) cytoplasm tapers-some cast off as residual bodies e) mitochondria move towards tail; become arranged in spiral fashion around developing tail; part of tail containing spiral-arranged mitochondria known as middle piece f) tail continues to elongate into principle piece and end piece note-in all stages from primary spermatocyte to spermatid stage, cells are connected by cytoplasmic bridges (due to incomplete cytokinesis); synchronous development occurs |
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Describe Sertoli cells
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1) elongated pyramidal cells, little visible chromatin, well-defined nucleolus, irregular nucleus (long axis of nucleus is perpendicular to basal lamina)
2) rest on basal lamina; cells extend to lumen 3) cells of the spermatogenic lineage are embedded in sides of Sertoli cells. 4) tight junctions present b/t Sertoli cells (part of Blood- Testes barrier) 5) functions: a) nutrition b) support of spermatogenic cells c) phagocytosis (esp. residual bodies of spermatids) 6) extremely resistant to adverse conditions (infections, malnutrition, x-rays) 7) contain abundance of lysosomes (due to involvment in phagocytosis of residual bodies) |
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Describe the blood-testes barrier
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1) presence of jxns b/t myoid cells
2) tight junctions b/t Sertoli cells 3) proteins of seminal lineage are secluded Ags; produced after birth thus Abs could form against them |
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Describe straight tubules and rete testes
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1. Straight Tubules (tubuli recti)
a. Seminiferous tubules in each lobule join at apex to form single, straight tubule b. lined by Sertoli cells ONLY (simple columnar epithelium) 2. Rete Testes a. extensive labyrinth of anastomosing, very irregular channels b. lined by simple cuboidal epithelium |
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Describe efferent ductules
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a. 8-15 in number
b. lined by simple columnar alternating w/ simple cuboidal epithelium c. externally, tubules are regular in outline; internal lining is irregular (corrugated) due to varying heights of cells d. some epithelial cells have cilia to help transport sperm to epididymis (ONLY motile lining cells in entire duct system) e. each ductule surrounded by thin layer of circularly arranged smooth muscle cells f. The efferent ductules form head of epididymis |
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Describe the ductus epididymis
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a. forms body and tail of epididymis
b. highly coiled c. sperm acquires motility and optimum fertilizability d. lined by pseudostratified columnar epithelium w/ stereocilia e. thin layer of circularly arranged smooth muscle cells around outer part of tubule f. sperm stored in tail until ejaculation |
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Describe the Ductus (Vas) deferens
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a. lined by pseudostratified columnar epithelium (some w/ stereocilia)
b. muscularis portion of wall formed by 3 layers of smooth muscle cells c. surrounding muscularis is fibrous adventitia d. pathway: • ascends from scrotum • traverses inguinal canal • courses down side wall of pelvis towards posterior part of prostate gland • just prior to termination, duct dilates to form AMPULLA of vas |
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Describe the ejaculatory duct
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a. formed by union of ampulla of vas + excretory duct of seminal vesicle
b. pierces prostate to open into urethra c. lined by simple columnar or pseudostratified columnar epithelium d. supporting wall is fibrous C.T. only |
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Describe the seminal vesicle
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1. tortuous elongated diverticulum off of ductus deferens
2. Situated post. to prostate 3. Wall a) external CT adventitia b) small muscle coat: inner-circular; outer-longi c) highly folded mucosa-high 1° folds branch into 2° and 3° folds; folds merge w/ one another to form compartments d) lamina propria-loose CT, richly vascularized e) epithelium-many variations; usually pseudostratified columnar 4. Secretion a) yellowish, viscid fluid b) contains fructose (energy for sperm) c) amount can be measured & utilized as test for androgens 5. Dependence upon testosterone-castration followed by involution and loss of secretory functions; restored by administration of testosterone extract 6. Seminal vesicle doesn't store sperm 7. Seminal Vescilcle duct joins vas deferens to form Ejaculatory Duct |
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Describe the prostate gland
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1. Surrounds urethra at its origin
2. Aggregate of small compound tubuloalveolar glands 3. Drains into prostatic urethra by small ducts 4. Glandular elements concentrically arranged around urethra: a) mucosal b) submucosal c) main (principle glands)-constitute bulk of gland. 5. Glandular epithelium is simple cuboidal to simple columnar, height varies w/ activity levels 6. Stroma-glands embedded in dense fibromuscular stroma w/ numerous strands of small muscle fibers contained w/ stroma 7. Secretion (milky liquid) contains: 1) Prostatic acid phosphatase (PAP)-amount related to amount of activity; sensitive test for assessing prostatic function 2) Citric Acid 3) Fibrinolysin (liquifies semen) 4) Prostatic Specific Antigen (PSA) 8. Prostatic concretions present |
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Describe bulbourethral glands
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1. Paired, size of pea, located behind membranous urethra in U-G diaphragm
2. Compound tubuloalveolar glands; duct enters posterior portion of cavernous (penile) urethra 3. Glands surrounded by CT capsule 4. Epithelium varies from simple cuboidal to simple columnar 5. Secretion is clear viscid mucous |
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Describe the penis
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A. Function
1. Common outlet for urine and seminal fluid 2. Copulatory organ B. Structure 1. Glans penis-caps distal end 2. Corpora cavernosus: a. paired, forms most of dorsum of body of penis b. surrounded by dense CT (tunica albuginea) c. trabeculae from t. albuginea forms dense internal network d. spaces in network are lined by endothelium forming blood sinuses e. C. cavernosum traversed by deep A of penis 3. Corpus spongiosum a. cavernous tissue; thinner than corpus cavernosum b. surrounded by thin tunica albuginea 4. Skin a. "thin" skin covers entire penis b. no fat in skin c. contains sweat glands and occasional sebaceous glands |
