Semen (Textbook) Flashcards
Semen Fractions and Sources
Sources:
- Testes
- Epididymis
- Seminal vesicles
- Prostate gland
- Bulbourethral glands
Sperm Secretion
Testes are paired glands in the scrotum that contain
the seminiferous tubules. These tubules contain germ cells for the production of spermatozoa in the epithelial cells.
Germ cells are supported by Sertoli cells
Sertoli cells
Sertoli cells provide support and nutrients for the germ cells as they undergo mitosis and meiosis (spermatogenesis).
Sperm Development
Once spermatogenesis is complete, the immature sperm (nonmotile) enter the epididymis where the sperm mature and develop flagella.
The entire process takes approximately 90 days.
Sperm Transport
Ejaculatory ducts receive sperm from the
ductus deferens and fluid from the seminal vesicles. The seminal vesicles produce most of the fluid present in semen (60% to 70%), and this fluid is the transport medium for the sperm.
The fluid contains a high concentration of fructose and flavin.
Semen Composition
Spermatozoa: 5%
Seminal fluid: 60% to 70%
Prostate fluid: 20% to 30%
Bulbourethral glands: 5%
Prostate Gland
- Located just below the bladder, surrounds the upper urethra and aids in propelling the sperm through the urethra by contractions during ejaculation.
- Approximately 20% to 30% of the semen volume is acidic fluid produced by the prostate gland
- Prostate Gland milky acidic fluid contains acid phosphatase, citric acid, zinc, and proteolytic enzymes responsible for both the coagulation and liquefaction of the semen following ejaculation.
Bulbourethral Glands
Located below the prostate, contribute about 5% of the fluid volume in the form of a thick, alkaline mucus that helps to neutralize acidity from the prostate secretions and the vagina.
Specimen Collection
- Most of the sperm are contained in the first portion of the ejaculate
- Imperative for accurate testing of both fertility and postvasectomy specimens.
- First portion of the ejaculate is missing: sperm count will be decreased, the pH falsely increased, and the specimen will not liquefy.
- Last portion of ejaculate is missing: semen volume is decreased, the sperm count is falsely increased, the pH is falsely decreased, and the specimen will not clot.
Pre- and Post- Specimen Collection Guidelines
- Specimens are collected following a period of sexual abstinence of at least 2 days to not more than 7 days.
- Specimens should be kept at room temperature and delivered to the laboratory within 1 hour of collection, and those awaiting analysis should be kept at 37°C
Fertility Evaluation
Consists of both macroscopic and microscopic examination.
Parameters reported include appearance, volume, viscosity, pH, sperm concentration and count, motility, and morphology.
During microscopic examination, WBCs must
be differentiated from immature sperm (spermatids).
Factors Affecting Motility Analysis
Urine is toxic to sperm, thereby affecting evaluation of motility.
Semen Liquefication
- A fresh semen specimen is clotted and should liquefy within 30 to 60 minutes after collection
- Failure to liquefaction after 60 minutes may be caused by a deficiency in prostatic enzymes
- If liquefication hasn’t occured after 2 hours, an equal volume of physiologic PBS or proteolytic enzymes such as alphachymotrypsin or bromelain may be added to induce liquefaction
Semen Volume
Normal volume: 2 - 5 mL
Decreased volume: associated with infertility and may indicate improper functioning of one of the semen producing organs, primarily the seminal vesicles.
Semen Viscosity
Droplets that form threads longer than 2cm are considered highly viscous and abnormal.