Page 476 - Anatomy and Physiology of Farm Animals, 8th Edition

Physiology of Male Reproduction / 461

(A) (B)
VetBooks.ir

(C) (D) (E)

Figure 25-6. Microscopic evaluation of bovine spermatozoa using light microscopy. An nigrosin‐eosin
stain is commonly used (A, B), though use of differential interference contrast (DIC) (C, D, E) can be useful.
Normal spermatozoa (A, C) and those with detached heads (B, white arrow), cytoplasmic droplets (B,
black arrow, E), or a coiled midpiece and tail (D). Source: images courtesy of Library of Reproduction
Images (LORI: https://lorimainsection.blogspot.ca/).

secretions and the presence of androgens Semen is collected and evaluated as part
(male sex steroids, testosterone, and dihy- of protocols to evaluate the fertility of
drotestosterone) in the epididymal fluids. breeding males, but no single characteris-
Morphologic changes (e.g., changes in tic of semen or spermatozoa is accepted as
nuclear chromatin and the acrosome) may a perfect gold standard for predicting the
also occur during the passage through the fertility of a given sample of semen. Some
epididymis. characteristics of semen that are evaluated
and appear to have some correlation with
potential fertility when considered together
Semen and Semen Technology are: (1) concentration of spermatozoa per
milliliter of semen; (2) motility characteris-
Semen consists of spermatozoa suspended tics of spermatozoa; and (3) morphologic
in the fluid secretions of the male acces- shape of the spermatozoa. The concentra-
sory sex organs. The fluid portion of semen tions of spermatozoa per milliliter and
(seminal plasma) functions as a transport normal morphologic features vary among
medium for the spermatozoa, and it con- species, and this should be considered
tains a variety of substances including vari- when evaluating semen.
ous electrolytes, fructose, citric acid, and Semen is also collected and used for
sorbitol. The fructose (a sugar) is a poten- breeding technologies such as artificial
tial source of energy for the spermatozoa. insemination and in vitro fertilization