Table Of Content,
This thesis having been approved by the
,
special Faculty Committee is accepted by
the Graduate School of the
,
University of Wyoming
in partial fulfillment of the requirements
for the degree of Master of Science___
__________
Dean of the Graduate School.
Tint0. August 21, 1950
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
C H R O M O S O M E S T U D I E S O F
D O M E S T I C A N I M A L S
by
H a r r y P. S a v e r y
A Thesis
Submitted to the Department
of Anim al Production and the
Graduate School of the University
of Wyoming in Partial Fulfillm ent
of Requirements for the Degree of
Master of Science
OBWttTY
□ F THE
UNIVERSITY OF WYOMING
LARAMIE
University of Wyoming
Laram ie, Wyoming
August,. 1950
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UMI Number: EP20620
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i 1EBARD ?wUi
ACKNOWLEDGEMENTS
The author wishes to acknowledge the courtesies and fine
cooperation he received from M r. Jim Davidson, sheep herdsman
at the University Farm , Dr. C. L. Davis, head of the B. A. I.
Pathological Laboratory in Denver, Colorado, in collecting the
m aterial used in this study; and Kay Studio in printing the pictures
used as references. Sincere gratitude is also expressed to Dr.
C. B. Roubicek, of the department, for his consultation and advice.
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TABLE OF CONTENTS
Page
IN TR O D U C TIO N ......................................................................................................... 1
REVIEW OF L IT E R A T U R E ............................................................................... 2
Sheep (Ovis aries) and Goat (Capra h irc u s )................................... 2
Swine (Sus s c ro fa )........................................................................................... 4
Cattle (Bos ta u ru s )........................................................................................... 5
Other Species and Techniques.................................................................. 6
MATERIALS AND T E C H N IQ U E S .................................................................. 11
M a te ria ls ................................................................................................................. 11
F ix a tiv e s ................................................................................................................. 12
P rocedures............................................................................................................. 13
S tain s.......................................................................................................................... 14
Photom icrography........................................................................................... 15
O BSERVATIO NS........................................................................................................ 18
D ISCUSSIO N................................................................................................................. 25
Sperm atogenesis................................................................................................ 25
S U M M A R Y ...................................................................................................................... 35
SELECTED R E F E R E N C E S ............................................................................... 37
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LIST OF FIGURES
Plate Page
I. Figure a. Typical tubule of a 97-day-old Columbia ram . 20
Figure b. Typical tubule of 104-day-old Columbia ram . 20
II. Figure a. Typical tubule of 118-day-old Columbia ram . 21
Figure b. Typical tubule of 150-day-old Columbia ram . 21
III. Figure a. Typical view of tubules of the 97-day-old
Columbia r a m ............................................................................................ 23
Figure b. Typical view of tubules of the 104-day-old
Columbia r a m ............................................................................................ 23
IV. Figure a. Typical view of tubules of the 118-day-old
Columbia r a m ............................................................................................ 24
Figure b. Typical view of tubules of the 150-day-old
Columbia r a m ............................................................................................ 24
V. Figure a. Section of a tubule showing spermatogonia,
prim ary spermatocytes, and Sertoli cells . . . . . . . . 26
Figure b. Section of a tubule showing dividing prim ary
spermatocytes, secondary spermatocytes, and
sperm atids.................................................................................................... 26
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V
Plate Page
VI. Figure a. E arly prophase stage........................................................... 28
Figure b. Mid-prophase s ta g e ........................................................... 28
VII. Figure a. Prim ary spermatocyte in early metaphase
division............................................................................................................. 29
Figures b - f. Polar views of prim ary spermatocytes in
the metaphase division.......................................................................... 29
V III. Figures a - d. Polar views of prim ary spermatocytes
in the metaphase stage.......................................................................... 31
Figure e. Late diakinesis showing te tra d s ................................ 31
IX. Figure a. Prim ary spermatocyte in early anaphase stage 32
Figures b - c. P rim ary spermatocytes in late anaphase
s ta g e ................................................................................................................. 32
Figure d. Chromatid bridge................................................................... 32
X. Figure a. Late anaphase stage with thickening of
achromatic fig u r e ................................................................................... 34
Figure b. P rim ary spermatocytes in various anaphase
stages......................................................,........................................................ 34
Figure c. P rim ary spermatocyte in telophase stage . . . 34
Figure d. Newly formed secondary spermatocyte . . . . 34
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INTRODUCTION
Cytological investigations become more important as animal
breeding plans for our domestic animals, namely, beef, sheep, and
swine, become more complex. A thorough understanding of the
chromosome complex helps us to determine when animals reach
sexual m aturity, what the effects of management and nutrition on
sexual m aturity are, what the breeding abilities of animals are, what
matings are feasible, and whether the offspring of such matings w ill
be capable to reproduce themselves. A critical examination of the
chromosome complex during the division cycles should also yield
significant information concerning the peculiarities of hereditary
transmission.
The purpose of this study was two-fold: (1) to study the chromo
some complex of domestic animals, and (2) to set up the new cyto
logical laboratory equipment only recently acquired by the Animal
Production Department. The first purpose is self-explanatory; the
second purpose entailed setting up the new Bausch and Lomb compound
research microscope and camera, determining which techniques were
best suited to this type of study, and reviewing comprehensively
literature pertaining to this field.
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2
REVIEW OF LITERATURE
Difficulty in counting the high chromosome number in the chromo
some complex, plus improper techniques, probably accounts for the
variations in chromosome counts reported by different investigators.
Sheep (Ovis aries) and Goat (Capra hircus)
Ahmed (1), working with testicular m aterial from Leicester
ram s, reported a diploid chromosome number of 54. He noted that
the chromosomes varied in size and shape, and that the sex chromo
somes consisted of a large X with a median centromere, and a
sm aller Y with a subterminal centromere. Using various fixatives,
Ahmed obtained his best results with the following:
Minouchi A - 1 part 2% Osmic acid
2 parts 1% Chromic acid
2 parts 3% Potassium bichromate
This was diluted with distilled water
in a 1:1 ratio.
Minouchi B - 1 part 2% Osmic acid
4 parts 1% Chromic acid
This was diluted with distilled water
in a 4:1 ratio.
The period of fixation was between 15 and 18 hours, and the sec
tions, which were cut 16 microns thick, were stained with gentian
violet.
Butarin (7), working with Arkar and fat-rum ped sheep, reported
a chromosome count of from 54 to 56 for the A rkar, and from 52 to 54
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