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Comparison of early conceptus mobility between mares and jennies
THERIOGENOLOGY
COMPARISON OF EARLY CONCEPTUS MOBILITY BETWEEN MARES AND JENNIES
C. Bessent
and O.J. Cinther
Department of Veterinary Science University of Wisconsin-Madison Madison, Wisconsin 53706 Received
for publication: Accepted:
April 21, 1987 November 13, 1987
ABSTRACT The characteristics of early intrauterine mobility of the conceptus were compared between ponies (n = 9) and donkeys (n = 9). The extensive mobility of the early conceptus, previously reported for ponies and horses, was found in donkeys as There were no significant differences between donkeys and ponies in the well. characteristics or patterns of mobility. However, the mean day of fixation was approximately one day later (P
Key words:
mares,
jennies,
embryo,
embryo
mobility
INTRODUCTION The equine embryonic vesicle is highly mobile within the uterus from the day of initial detection by ultrasonography (Days 9 to 11) until mobility ceases on a mean of Day 15 for ponies (I-4) or Day 16 for horses (5). The cessation of mobility has been called fixation (2). In ponies, mobility of the embryonic vesicle was most extensive on Days I I to 14 (4). During this time, the vesicle moved from one horn to the other an equivalent of 7 to 19 times per day in various experiments based on 2-h mobility trials (3-7). Although mobility of the horses and ponies, it has not this study was to determine donkeys and whether there are between ponies (Equus caballus)
conceptus has been studied over the past few years in been studied in other equine species. The purpose of whether the embryo mobility phenomenon exists in differences in mobility patterns or the day of fixation and donkeys (Equus asinus).
Supported by the College of Agricultural and Life Acknowledgments: The authors thank Stan Scraba for University of Wisconsin-Madison. assistance.
APRIL
1988 VOL. 29 NO. 4
Sciences, technical
913
THERIOGENOLOGY
MATERIALS
AND METHODS
The experiment was conducted during July and August using sin le-ovulating, pregnant, nonlactating, mature jennies (n q 9) and pony mares (n = 99, of unknown breeding. The animals were examined daily by ultrasound on Days 9 through 24 (Day 0 = ovulation) for detection of the embryonic vesicle. The ultrasound examinations were performed as described (3,8) with a linear-array, real-time scanner equipped with a 5 MHz transducer (EQ-210, Equisonics Inc., Roselle, IL). Vesicle location and diameter were determined daily in all animals. Two-hour mobility trials were performed on Days 10, 13, and 16; Days II, 14, and 17; or Days 12, 15, and 18 (n = 3 animals on each set of days for each species). Each mobility trial consisted of 25 location determinations over two consecutive hours (one location determination every 5 min) as described (3). The uterus was divided into right horn, left horn, and body. Each uterine horn and the body were further divided into three approximately equal segments (cranial one-third, middle one-third, and caudal one-third), as described (31, for a total of nine uterine segments. Fixation was defined as failure to detect a change in location during a 2-h trial and over all subsequent daily examinations to Day 24. A factorial analysis of variance was used to determine whether the number of times per 2-h trial that the embryonic vesicle was in the uterine body was different between species and among days. Duncan’s multiple range test was used to locate the differences among means. The number of animals in which the embryonic vesicle was in the uterine body during daily examinations was compared between species and days by a Chi-square analysis. The number of times the vesicle was in each horn segment on Days 11 through 14 was examined using general linear models multivariate analysis. A two-way (day and species) factorial analysis of variance was used to examine the mean number of times the embryonic vesicle changed locations between successive determinations during a 2-h trial. The patterns examined were movement between segments, between uterine body and a horn, and between uterine horns. The frequency of entry of the embryonic vesicle into a given uterine horn from the uterine body during a 2-h trial was examined using Chi-square goodness-offit analyses to determine differences between species or between the expected frequency for equality and the observed frequency. The relationships considered were side (left horn versus right horn), side of location of corpus luteum, side previously occupied, and side of eventual fixation. A one-way analysis of variance was used to determine if there was a species difference between the mean day of fixation and the mean vesicle diameter on the day of fixation. Regression analyses were used to characterize the growth of the embryonic vesicle in each species over Days II to 16.
RESULTS The embryonic vesicle was first detected on Day 10 in more (P(O.01) ponies (8/9) than donkeys (3/9). The changes in diameter (height) of the conyptus were characterized by a linear regression over Days II to 16 in each species (R = 99% for each species; Figure I). The interaction between species and day tended to be significant (P
914
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
m
1
25
0
I
1
I
I
I
I
I
11
12
13
14
15
16
Days postovulation
Figure
1.
Linear regression lines characterizing the growth of the embryonic vesicle over Days 11 to 16 in mares and jennies. The open squares and the solid diamonds are actual means for mares and jennies, respectively. Interaction (P
During 2-h mobility trials, the mean number of times the embryonic vesicle was found in the uterine body was different (P
APRIL 1988 VOL. 29 NO. 4
915
I’HERIOGENOLOGY
Table
1.
Mean (2 SEM) number and proportional number of times embryonic vesicle was in the uterine body during 2-h mobiity daily examinations, respectively
Source
of data
Donkeys
2-h trialsa Dav Day Day Day Day Day Daily Day Day Day Day Day Day
a
bci
10 II 12 13 14 15
that trials
the and
Ponies
-_ 11.0 f 3.6 (3) 13.7 f 5.4 (3) 6.0 + 3.3 (3) 3.7 + 3.7 (3) 3.6 + 1.9 (3)
examinationse 10 II 12 13 14 15
2/3 5/8 2/8 2/9 2/9 l/9
(67%) (62%) (25%) (22%) (22%) (11%)
61% 4/7 3/9 l/9 l/9 o/9
Three animals per day for each species. Twenty-five per trial. Difference (PCO.05) among days for ponies significant difference between species.
(75%) (57%) (33%) (11%) (11%) (0%)
location determinations but not for donkeys. No
Any two means with no common superscripts are different (PCO.05). Difference (P(O.01) among days for ponies and for donkeys but no significant differences between species.
The mean day of fixation occurred later (P
916
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
Table
2.
Percentage of times during location in a uterine horn
2-h trials
that
the vesicle
was in a given
Horn segment
Species and Day
Donkeys Day I1 Day 12 Day 13 Day 14 Combined Ponies Day Day Day Day Day
Days
10 II 12 13 14
Combined
Difference significant
Days
Cranial l/3 (%)
Middle l/3 1%)
Caudal l/3 (96)
32 27 47 53
20 8 15 16
4 12 15 16
40
15
12
17 41 31 36 69
3 17 1 II 13
0 II II
23 7
49
II
13
(P
for
both
ponies
and donkeys.
No
DISCUSSION The extensive mobility of the early conceptus previously reported for ponies and horses was demonstrated in donkeys. No differences were found between species (donkeys versus ponies) in the characteristics of embryo mobility. The mobility patterns for both species were similar to those previously reported for ponies, including I) more frequent location of the embryonic vesicle in the uterine body versus a horn when initially detected (Days 10 or I I) than on subsequent days (4,6,7); 2) more frequent location in the caudal segment of a horn than in the middle or cranial segments (4,6,7); and 3) no effect of side for entry of the vesicle from the body into a horn whether side is defined according to left and right, location of corpus luteum, horn previously occupied, or location of eventual fixation (4,5). The extent and days of mobility were also similar to the results of previous studies in ponies and horses (3-7).
APRIL 1988 VOL. 29 NO. 4
917
THERIOGENOLOGY
Table
3.
Mean (k SEM) number of times the embryonic vesicle between successive determinations during a 2-h trial
changed
locations
Species Pattern of change and Day
Donkeys
Between segmentsa Dav 10 Da; II Day 12 Day 13 Day 14 Day 15 Between uterine Day 10 Day II Day 12 Day 13 Day i4 Day 15
body and a horn
Between uterine Day 10 Day II Day 12 Day 13 Day 14 Day I5
horns
_-
Ponies
10.3 9.0 9.0 6.3 6.7
+ f + t +
2.3 2.1 1.5 3.8 4.5
4.0 9.0 6.7 12.7 4.0 0.7
? f ? f f +
0.6Cd 1.obc 1.8’ 2Jb 2.1cd 0.6d
2.7 3.7 2.3 1.7 3.7
t f t 2 ?
0.3 2.2 1.4 1.7 2.4
1.3 3.7 3.0 4.3 1.0 0.7
+ f 2 2 f +
0.9 1.4 1.2 1.2 1.0 0.6
0.3 0.3 0.6 0.7 0.3
0.3 1.0 0.7 0.7 0.3 0.0
Lt 0.3 ? 0.6 f 0.3 f 0.3 ?r 0.3 t 0.0
-0.3 0.3 1.0 0.7 0.7
+ * + + +
a The uterine body and both horns were each divided into three approximately b_d equal segments yielding nine segments. Any two means with no common superscripts are different (P
918
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
Table
4.
Frequency of entry of the embryonic vesicle from the uterine body during a 2-h trial
Relationship between horns according to
into a given
uterine
horn
Ponies
Donkeys
Side Left Right Location of Corpus Same side Opposite side Side previously Same Opposite Side of eventuai Same Opposite
IO/22 12/22
(46%) (54%)
12123 (52%) I l/23 (48%)
7122 15/22
02%) (68%)
I2/22 IO/22
(55%) (45%)
7/16 9/16
(44%) (56%)
7/15 8/15
(47%) (53%)
M/23 8/23
(65%) (35%)
IO/22 12/22
(46%) (54%)
Iuteum
occupied
fixation
No significant differences between species or between equality (50%/50%) for any of the relationships between
the observed horns.
frequency
and
The mean day of fixation for the ponies (Day 14.7) was similar to that found in previous studies (2,4-7). However, the mean day of fixation occurred approximately one day later in the donkeys (Day 15.6). In both species, fixation occurred in the caudal portion of one of the uterine horns. Fixation has been postulated to be a function of increasing expansion of the conceptus and increasing tone of the uterine horns so that the mobile vesicle eventually becomes trapped at the flexure in a caudal uterine horn (2,5,9). In a comparison between ponies and horses, fixation occurred one day later in horses (5); the difference between mare types was attributed to the larger uterus in horses since there was no difference between horses and ponies in the size of the conceptus. In the present study, the conceptus was initially smaller in the jennie; the donkey embryonic vesicles did not appear to reach the diameter of the pony vesicles until Day 16 (Figure I). Perhaps the later fixation in the jennies was due, at least in part, to the smaller diameter of the embryonic vesicle.
APRIL
1988 VOL.
29 NO. 4
919
THERIOGENOLOGY
REFERENCES 1.
Ginther, 0.X 611 (1983).
Mobility
2.
Ginther, 0.X Theriogenology
Fixation 19:613-623
3.
Intrauterine movement of the early Ginther, 0.3. postpartum mares. Theriogenotogy 2:633-644 (1984).
4.
Leith, G.S. and Ginther, 0.X Characterization of intrauterine early equine conceptus. Theriogenology g:401-408 (1984).
5.
Ultrasonic Imaging and Reproductive Ginther, O.J. Equiservices, Cross Plains, WI, 1986, pp. 230-241.
6.
Leith, G.S. and Ginther, O.J. Mobility of the conceptus in the mare. Theriogenology 24:701-711 (1985).
7.
Ginther, g:83-95
8.
Ginther, 0.3. of the mare: 201 (1983).
9.
Ginther, uterus.
920
O.J. Mobility (1984).
of the early
equine
conceptus.
and orientation ( 1983).
of
of twin embryonic
Theriogenology
the
vesicles
early
conceptus
mobility
Events
in mares.
in
and
of the
Mares.
contractions
Theriogenology
of the reproductive tract J. Equine Vet. Sci. 2:195-
between
APRIL
conceptus.
in barren
and uterine
and Pierson, R.A. Ultrasonic evaluation principles, equipment and techniques.
Dynamic physical interactions O.J. Equine Vet. J. Suppl. 3:41-47 (1985).
equine
fi:608-
the equine
1988 VOL.
embryo
29 NO. 4
and
COMPARISON OF EARLY CONCEPTUS MOBILITY BETWEEN MARES AND JENNIES
C. Bessent
and O.J. Cinther
Department of Veterinary Science University of Wisconsin-Madison Madison, Wisconsin 53706 Received
for publication: Accepted:
April 21, 1987 November 13, 1987
ABSTRACT The characteristics of early intrauterine mobility of the conceptus were compared between ponies (n = 9) and donkeys (n = 9). The extensive mobility of the early conceptus, previously reported for ponies and horses, was found in donkeys as There were no significant differences between donkeys and ponies in the well. characteristics or patterns of mobility. However, the mean day of fixation was approximately one day later (P
Key words:
mares,
jennies,
embryo,
embryo
mobility
INTRODUCTION The equine embryonic vesicle is highly mobile within the uterus from the day of initial detection by ultrasonography (Days 9 to 11) until mobility ceases on a mean of Day 15 for ponies (I-4) or Day 16 for horses (5). The cessation of mobility has been called fixation (2). In ponies, mobility of the embryonic vesicle was most extensive on Days I I to 14 (4). During this time, the vesicle moved from one horn to the other an equivalent of 7 to 19 times per day in various experiments based on 2-h mobility trials (3-7). Although mobility of the horses and ponies, it has not this study was to determine donkeys and whether there are between ponies (Equus caballus)
conceptus has been studied over the past few years in been studied in other equine species. The purpose of whether the embryo mobility phenomenon exists in differences in mobility patterns or the day of fixation and donkeys (Equus asinus).
Supported by the College of Agricultural and Life Acknowledgments: The authors thank Stan Scraba for University of Wisconsin-Madison. assistance.
APRIL
1988 VOL. 29 NO. 4
Sciences, technical
913
THERIOGENOLOGY
MATERIALS
AND METHODS
The experiment was conducted during July and August using sin le-ovulating, pregnant, nonlactating, mature jennies (n q 9) and pony mares (n = 99, of unknown breeding. The animals were examined daily by ultrasound on Days 9 through 24 (Day 0 = ovulation) for detection of the embryonic vesicle. The ultrasound examinations were performed as described (3,8) with a linear-array, real-time scanner equipped with a 5 MHz transducer (EQ-210, Equisonics Inc., Roselle, IL). Vesicle location and diameter were determined daily in all animals. Two-hour mobility trials were performed on Days 10, 13, and 16; Days II, 14, and 17; or Days 12, 15, and 18 (n = 3 animals on each set of days for each species). Each mobility trial consisted of 25 location determinations over two consecutive hours (one location determination every 5 min) as described (3). The uterus was divided into right horn, left horn, and body. Each uterine horn and the body were further divided into three approximately equal segments (cranial one-third, middle one-third, and caudal one-third), as described (31, for a total of nine uterine segments. Fixation was defined as failure to detect a change in location during a 2-h trial and over all subsequent daily examinations to Day 24. A factorial analysis of variance was used to determine whether the number of times per 2-h trial that the embryonic vesicle was in the uterine body was different between species and among days. Duncan’s multiple range test was used to locate the differences among means. The number of animals in which the embryonic vesicle was in the uterine body during daily examinations was compared between species and days by a Chi-square analysis. The number of times the vesicle was in each horn segment on Days 11 through 14 was examined using general linear models multivariate analysis. A two-way (day and species) factorial analysis of variance was used to examine the mean number of times the embryonic vesicle changed locations between successive determinations during a 2-h trial. The patterns examined were movement between segments, between uterine body and a horn, and between uterine horns. The frequency of entry of the embryonic vesicle into a given uterine horn from the uterine body during a 2-h trial was examined using Chi-square goodness-offit analyses to determine differences between species or between the expected frequency for equality and the observed frequency. The relationships considered were side (left horn versus right horn), side of location of corpus luteum, side previously occupied, and side of eventual fixation. A one-way analysis of variance was used to determine if there was a species difference between the mean day of fixation and the mean vesicle diameter on the day of fixation. Regression analyses were used to characterize the growth of the embryonic vesicle in each species over Days II to 16.
RESULTS The embryonic vesicle was first detected on Day 10 in more (P(O.01) ponies (8/9) than donkeys (3/9). The changes in diameter (height) of the conyptus were characterized by a linear regression over Days II to 16 in each species (R = 99% for each species; Figure I). The interaction between species and day tended to be significant (P
914
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
m
1
25
0
I
1
I
I
I
I
I
11
12
13
14
15
16
Days postovulation
Figure
1.
Linear regression lines characterizing the growth of the embryonic vesicle over Days 11 to 16 in mares and jennies. The open squares and the solid diamonds are actual means for mares and jennies, respectively. Interaction (P
During 2-h mobility trials, the mean number of times the embryonic vesicle was found in the uterine body was different (P
APRIL 1988 VOL. 29 NO. 4
915
I’HERIOGENOLOGY
Table
1.
Mean (2 SEM) number and proportional number of times embryonic vesicle was in the uterine body during 2-h mobiity daily examinations, respectively
Source
of data
Donkeys
2-h trialsa Dav Day Day Day Day Day Daily Day Day Day Day Day Day
a
bci
10 II 12 13 14 15
that trials
the and
Ponies
-_ 11.0 f 3.6 (3) 13.7 f 5.4 (3) 6.0 + 3.3 (3) 3.7 + 3.7 (3) 3.6 + 1.9 (3)
examinationse 10 II 12 13 14 15
2/3 5/8 2/8 2/9 2/9 l/9
(67%) (62%) (25%) (22%) (22%) (11%)
61% 4/7 3/9 l/9 l/9 o/9
Three animals per day for each species. Twenty-five per trial. Difference (PCO.05) among days for ponies significant difference between species.
(75%) (57%) (33%) (11%) (11%) (0%)
location determinations but not for donkeys. No
Any two means with no common superscripts are different (PCO.05). Difference (P(O.01) among days for ponies and for donkeys but no significant differences between species.
The mean day of fixation occurred later (P
916
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
Table
2.
Percentage of times during location in a uterine horn
2-h trials
that
the vesicle
was in a given
Horn segment
Species and Day
Donkeys Day I1 Day 12 Day 13 Day 14 Combined Ponies Day Day Day Day Day
Days
10 II 12 13 14
Combined
Difference significant
Days
Cranial l/3 (%)
Middle l/3 1%)
Caudal l/3 (96)
32 27 47 53
20 8 15 16
4 12 15 16
40
15
12
17 41 31 36 69
3 17 1 II 13
0 II II
23 7
49
II
13
(P
for
both
ponies
and donkeys.
No
DISCUSSION The extensive mobility of the early conceptus previously reported for ponies and horses was demonstrated in donkeys. No differences were found between species (donkeys versus ponies) in the characteristics of embryo mobility. The mobility patterns for both species were similar to those previously reported for ponies, including I) more frequent location of the embryonic vesicle in the uterine body versus a horn when initially detected (Days 10 or I I) than on subsequent days (4,6,7); 2) more frequent location in the caudal segment of a horn than in the middle or cranial segments (4,6,7); and 3) no effect of side for entry of the vesicle from the body into a horn whether side is defined according to left and right, location of corpus luteum, horn previously occupied, or location of eventual fixation (4,5). The extent and days of mobility were also similar to the results of previous studies in ponies and horses (3-7).
APRIL 1988 VOL. 29 NO. 4
917
THERIOGENOLOGY
Table
3.
Mean (k SEM) number of times the embryonic vesicle between successive determinations during a 2-h trial
changed
locations
Species Pattern of change and Day
Donkeys
Between segmentsa Dav 10 Da; II Day 12 Day 13 Day 14 Day 15 Between uterine Day 10 Day II Day 12 Day 13 Day i4 Day 15
body and a horn
Between uterine Day 10 Day II Day 12 Day 13 Day 14 Day I5
horns
_-
Ponies
10.3 9.0 9.0 6.3 6.7
+ f + t +
2.3 2.1 1.5 3.8 4.5
4.0 9.0 6.7 12.7 4.0 0.7
? f ? f f +
0.6Cd 1.obc 1.8’ 2Jb 2.1cd 0.6d
2.7 3.7 2.3 1.7 3.7
t f t 2 ?
0.3 2.2 1.4 1.7 2.4
1.3 3.7 3.0 4.3 1.0 0.7
+ f 2 2 f +
0.9 1.4 1.2 1.2 1.0 0.6
0.3 0.3 0.6 0.7 0.3
0.3 1.0 0.7 0.7 0.3 0.0
Lt 0.3 ? 0.6 f 0.3 f 0.3 ?r 0.3 t 0.0
-0.3 0.3 1.0 0.7 0.7
+ * + + +
a The uterine body and both horns were each divided into three approximately b_d equal segments yielding nine segments. Any two means with no common superscripts are different (P
918
APRIL 1988 VOL. 29 NO. 4
THERIOGENOLOGY
Table
4.
Frequency of entry of the embryonic vesicle from the uterine body during a 2-h trial
Relationship between horns according to
into a given
uterine
horn
Ponies
Donkeys
Side Left Right Location of Corpus Same side Opposite side Side previously Same Opposite Side of eventuai Same Opposite
IO/22 12/22
(46%) (54%)
12123 (52%) I l/23 (48%)
7122 15/22
02%) (68%)
I2/22 IO/22
(55%) (45%)
7/16 9/16
(44%) (56%)
7/15 8/15
(47%) (53%)
M/23 8/23
(65%) (35%)
IO/22 12/22
(46%) (54%)
Iuteum
occupied
fixation
No significant differences between species or between equality (50%/50%) for any of the relationships between
the observed horns.
frequency
and
The mean day of fixation for the ponies (Day 14.7) was similar to that found in previous studies (2,4-7). However, the mean day of fixation occurred approximately one day later in the donkeys (Day 15.6). In both species, fixation occurred in the caudal portion of one of the uterine horns. Fixation has been postulated to be a function of increasing expansion of the conceptus and increasing tone of the uterine horns so that the mobile vesicle eventually becomes trapped at the flexure in a caudal uterine horn (2,5,9). In a comparison between ponies and horses, fixation occurred one day later in horses (5); the difference between mare types was attributed to the larger uterus in horses since there was no difference between horses and ponies in the size of the conceptus. In the present study, the conceptus was initially smaller in the jennie; the donkey embryonic vesicles did not appear to reach the diameter of the pony vesicles until Day 16 (Figure I). Perhaps the later fixation in the jennies was due, at least in part, to the smaller diameter of the embryonic vesicle.
APRIL
1988 VOL.
29 NO. 4
919
THERIOGENOLOGY
REFERENCES 1.
Ginther, 0.X 611 (1983).
Mobility
2.
Ginther, 0.X Theriogenology
Fixation 19:613-623
3.
Intrauterine movement of the early Ginther, 0.3. postpartum mares. Theriogenotogy 2:633-644 (1984).
4.
Leith, G.S. and Ginther, 0.X Characterization of intrauterine early equine conceptus. Theriogenology g:401-408 (1984).
5.
Ultrasonic Imaging and Reproductive Ginther, O.J. Equiservices, Cross Plains, WI, 1986, pp. 230-241.
6.
Leith, G.S. and Ginther, O.J. Mobility of the conceptus in the mare. Theriogenology 24:701-711 (1985).
7.
Ginther, g:83-95
8.
Ginther, 0.3. of the mare: 201 (1983).
9.
Ginther, uterus.
920
O.J. Mobility (1984).
of the early
equine
conceptus.
and orientation ( 1983).
of
of twin embryonic
Theriogenology
the
vesicles
early
conceptus
mobility
Events
in mares.
in
and
of the
Mares.
contractions
Theriogenology
of the reproductive tract J. Equine Vet. Sci. 2:195-
between
APRIL
conceptus.
in barren
and uterine
and Pierson, R.A. Ultrasonic evaluation principles, equipment and techniques.
Dynamic physical interactions O.J. Equine Vet. J. Suppl. 3:41-47 (1985).
equine
fi:608-
the equine
1988 VOL.
embryo
29 NO. 4
and