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Development of the testis in the ring-necked pheasant.

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DEVELOPMENT O F T H E TESTIS I N T H E
RING-NECKED PHEASANT
C. N. KIRKPATRICK AND F. N. ANDREWS
Department of Forestry and Conservation and Department of Animal Husbandry,
Purdue University, Lafayette, Indiana
ONE TEXT FIGURE AND ONE PLATE (FOUR FIGURES)
I n most vertebrates the production of mature spermatozoa is not a
continuous process but tends to be limited to a particular season of the
year. With a few possible exceptions spermatogenesis is a seasonal
phenomenon in wild species of birds, and even in the domestic fowl
which has been selected f o r continuous reproduction, season still influences semen production. (Wheeler and Andrews, '43).
Studies of spermatogenesis in several species of passerine birds have
revealed that season has a definite influence upon testicular activity.
The reports of Rowan ( '29) on the junco (Junco hyemalis), Bissonnette
and Chapnick ( '30) on the starling (Sturnus vulgaris), Kirschbaum
and Ringoen ( '36) on the sparrow (Passer domesticus), Blanchard
( '41) on the white-crowned sparrow (Zonotrichia leucophrys), Wolfson ('42) on the Oregon junco (Junco oreganus), and others have
shown, in general, that spermatogenesis and testis size are closely correlated, that testes of minimal size and activity are found during the
fall and winter months, that testis size and spermatogenic activity are
maximum in the spring and early summer, and that testicular involution begins in the summer and continues until the testis becomes inactive in the fall.
Because of the technical difficulties involved the relationships of age
and testicular development have not been investigated in wild birds.
I n the domestic fowl Hogue and Schnetzler ( '37) reported that in the
Barred Plymouth Rock the seminiferous tubules were composed chiefly
of spermatogonia during the first 8 weeks of life. Testis weight was
approximately doubled between the eighth and twelfth weeks and primary and secondary spermatocytes were observed. At 18 weeks of age
1 Journal Paper number 155, of the Purdue University Agricultural Experiment Station, the
Indiana Department of Conservation cooperating. The data in table 1 were used in a thesis
presented t o the University of Wisconsin Graduate School by the senior author in partial fulfillment of the requirements for the Doctor of Philosophy degree.
31 7
318
C. M. I-CIRIIPATRICK AND F. N. ANDREWS
the testis weights were similar to those of mature males and fully
formed spermatozoa were present,. Parker et al. ('42) found that in
White Leghorn and New Hampshire males rapid testicular development was initiated between the eighth and twelfth weeks and that mature testis size was approached at 24 and 30 weeks in Leghorns and
New Hampshires respectively. Spermatids were not present in either
breed at 8 weeks but spermatozoa were observed in both at 12 weeks
of age.
Although it has long been known that the ring-necked pheasant
(Phasianus colchicus torquatus) is a seasonal breeder, the development
and function of the testis has not been investigated. I n a preceding
paper dealing with this species Kirkpatrick ('44) reported on the relation of age and season to body weights and to growth of organs (including gonads). The testis material was reserved for more intensive
study and is presented below.
MATERIALS AND METHODS
The testes of eighty normal ring-necked pheasants ranging in age
from 16 to 362 days were immediately removed at the time of autopsy,
weighed, and fixed in Bouin's fluid. They were subsequently dehydrated
in butyl alcohol, sectioned at 8 microns, and stained in hematoxylin
and eosin. Preparations from seventy-two birds were studied histologically and findings recorded in figure 1.
RESULTS
The influence of age on testis weight is summarized in table 1. The
development of the gonads, as measured by weight, appeared to be
characterized by four fairly well defined stages, of which the fourth is
the most conspicuous (cf. Rirkpatrick, '44,fig. 2). Since the number
of pheasants observed in each age group is small the range in age of
each of the four growth phases should be considered as an approximate
rather than an absolute limit and it is recognized that considerable individual variation exists. The first growth phase was characterized by
a very gradual increase in testis weight and appeared to end somewhere
between the fifty-sixth and eighty-first days after hatching. The second
stage, from the eighty-first to the one hundred forty-fourth days, was
one of rapid increase in testis weight. This was followed by a period of
involution and decreased gonad weight which extended from soon
after the one hundred forty-fourth to the two hundred thirty-sixth day
of age. The fourth, and most important phase of development, the at-
319
DEVELOPMENT O F THE PHEASANT TESTIS
tainment of mature testis size and full spermatogenesis, was initiated
at approximately 236 days of age and was completed at about 334 days.
This final stage of development represents the period of seasonal
spermatogenesis in the ring-necked pheasant and occurred in the latter
part of March, April, and May.
TABLE 1
Growth and involution of gonad, thymus, and b w s a in the male ring-necked pheasant.
AQB
AUTOPSY
Date
6/5/41
6/17
7/3
7/8
7/15
8/3
8/9
(Dew)
16
28
43
49
56
75
81
8/15
87
94
101
109
116
130
144
151
165
172
191
215
236
257
271
285
306
334
362
8/22
8/29
9/6
9/13
9/27
10/11
10/18
11/1
11/8
11/27
12/22
1/12/42
2/2
2/16
312
3/23
4/20
5/18
~~
a
~
TESTIS WT.=
(tfVU??W)
-003 (1)
.010 (3)
.018 (1)
.023 (1)
.031 (3)
.084 (3)
.175 (1)
.115 (3)
.359 (3)
.154 (2)
.400 (3)
.254 (2)
.280 (2)
.264 (2)
.194 (2)
.164 (2)
.178 (2)
.162 (4)
A67 (5)
.210 (5)
.271 (5)
.990 (5)
1.840 (5)
8.220 (5)
11.960 (5)
10.400 (5)
THYMUS WT.*
{f&l.aWS)
.140
.499
.515
1.280
1.200
1.230
1.540
1.780
2.210
3.300
2.160
1.550
2.400
1.420
1.080
.352
.283
.129
.126
.168
(1)
(3)
(1)
(1)
(3)
(2)
(1)
(3)
(3)
(2)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(2)
(1)
BURSA DEPTH $2
(Bitlimetera)
11.6 (3)
16.5 (4)
(4)
(2)
(3)
(3)
(1)
(2)
(3)
(2)
(3)
(2)
(2)
(2)
(2)
(2)
(3)
(5)
(5)
(4)
(5)
(5)
(5)
(4)
0.0 (4)
17.0
17.5
15.6
16.6
20.0
20.5
18.6
22.5
20.3
19.0
20.0
18.5
17.0
16.5
15.0
13.5
12.8
7.0
7.0
7.2
3.8
0.0
~~
Figures within parentheses are number of birds observed for that age.
The histological study of the testis revealed that spermatogenic activity is closely correlated with the four growth phases previously described. These data are schematically presented in figure 1. The presence of primary and secondary spermatocytes, spermatids and spermatozoa is indicated by vertical bars. Spermatogonia appeared at all
stages.
During the first 81 days the seminiferous tubules were composed of
well organized spermatogonia and a few scattered primary sperma-
320
C. M. KIRKPATRICK AND F. N. ANDREWS
tocytes (fig. 2). Between the eighty-first and one hundred forty-fourth
days inclusively there was a marked increase in spermatogenesis. I n
six of eighteen testis sections studied secondary spermatocytes were
observed and in three of the birds spermatozoa were present (fig. 3).
From the one hundred forty-fourth to the two hundred fifty-seventh
days the seminiferous tubules showed little activity and contained only
spermatogonia and a few primary spermatocytes (fig. 4). With the
AGE 1W DAYS
Fig. 1 Spermatogenesis in the ring-necked pheasant in relation to age. The most advanced
germinal elements in each pheasant are indicated by the height of the vertical bars.
marked increase in testicular weight at about the two hundred seventieth day, the rate of spermatogenesis was greatly increased. Primary
and secondary spermatocytes and spermatids developed in rapid succession and spermatozoa appeared in large numbers (fig. 5).
DISCUSSION
The data presented in this study on the ring-necked pheasant are
similar to the findings of others in passerine birds in that there is a
definite seasonal period of full spermatogenesis. The results were
similar to those reported in the domestic fowl in that there was a period
of increased spermatogenic activity beginning about the twelfth week.
I n the domestic fowl full spermatogenesis is attained between the
eighteenth and thirtieth weeks and is then maintained at a more or
less continuous rate during the entire reproductive life of the cock.
The fact that the rate of spermatogenesis is temporarily increased at
approximately the twelfth week in the pheasant, and that spermatozoa
DEVELOPMENT OF THE PHEASANT TESTIS
321
may be produced is highly suggestive that present strains of domestic
fowls exhibited similar characteristics prior to the intensive selection
which has been practiced in recent years. Furthermore, it suggests
that a similar period of spermatogenic activity might occur in some
native gallinaceous birds to explain their unseasonal behavior which is
normally associated with the breeding season courtship. For example,
ruffed grouse (Bonasa umbellus) are known to drum at all seasons
(Allen, '34) and have been known to copulate in autumn (Forbush, '27).
MTisconsin prairie chickens (Tympanuchus cupido americanus) were
observed to boom sporadically in mid-October (Hammerstrom, '39),
and fall booming might have been indulged in by the now extinct heath
hen (Tympanuchus c. cupido) as reported by Gross ( '28). The sage
grouse ( Centrocercus urophasianus) sometimes struts in November
although the mating season is from March to June (Scott, '42).
As previously described (Kirkpatrick, '44) and as summarized in
table 1, the weight of the thymus gland and the depth of the bursa
reach maxima between 100 and 130 days and the involution of both organs begins immediately after this period. It is of considerable physiological interest that involution should be initiated during the interval
when testis size and activity are temporarily increased. It has been subsequently found (Kirkpatrick and Andrews, '44) that the injection of
testosterone propionate into normal and castrate male pheasants and
of stilbestrol into normal females produces highly significant decreases
in bursa depth in sexually immature pheasants. The data at hand
therefore suggest that there may be a physiological relationship between the stimulation of the testis at about 100 days of age and the
subsequent involution of the thymus and bursa. This hypothesis is in
harmony with Riddle's ( '28) observation that in the dove the increased
rate of growth of the gonads is coincident with beginning involution in
the bursa and thymus.
SUMMARY
Histological study of a series of pheasant testes revealed that spermatogenesis is closely correlated with four testicular growth phases.
The first phase, from hatching until between the fifty-sixth and the
eighty-first days, was characterized by a gradual increase in weight
and seminiferous tubules composed of spermatogonia and a few primary spermatocytes. The second stage, from the eighty-first day until
the one hundred forty-fourth day, was one of rapid increase in weight
and the production of spermatozoa in three of eighteen testes observed
during this period. The third stage, from after the one hundred forty-
322
C. M. KIRKPATRICK AND F. N. ANDREWS
fourth day to after the two hundred thirty-sixth day was one of testis
involution and the seminiferous tubules contained only spermatogonia
and a few primary spermatocytes. The final developmental stage and
the attainment of mature testis size and full spermatogenesis was initiated at approximately the two hundred fifty-seventh day. Full breeding condition of the testis was maintained through the three hundred
sixty-second day when the last autopsy was made.
The pheasant is similar to passerine birds in having a definite sea'sonal breeding period, but an interval of spermatogenic activity in late
summer juveniles is paralleled by the precocious spermatogenesis in
the domestic fowl at the same age (8 to 12 weeks). A number of native
grouse is also known to show indications of sexual activity in fall or
early winter.
Both thymus and bursa reached maxima between 100 and 130 days
after which involution of both organs began at once. This was the
same period when testis size and activity were temporarily increased
suggesting a physiological relationship between stimulation of the testis
at about 100 days and the subsequent involution of thymus and bursa.
LITERATURE CITED
ALLEN,A. A. 1934 Sex rhythm in the ruffed grouse (Bonasa nmbellus Linn.) and other
birds. Auk, vol. 51, pp. 180-199.
BISSONNETTE,
T. H., AND M. H. CHAPNICK 1930 Studies on the sexual cycle in birds: 11.
The normal progressive changes in the testis from November to May in the European
starling (Sturnus vulgaris), an introduced, nonmigratory bird. Am. J. Anat., vol.
45, pp. 307-343.
B L A N C H ~.B.
D ,D. 1941 The white-crowned sparrow (Zonotrichia leucophrys) of the Pacific
seaboard: environment and annual cycle, Univ. of Cal. Publ. Zool., vol. 46, pp. 1-178..
FORBUSR,
E. H. 1927 Birds of Massachusetts and other New England States. V. 2, Mass.
Dept. of Agri., Boston.
GROSS,A. 0. 1928 The Heath Hen. Mem. Bost. SOC. Nat. Hist., vol. 6, pp. 491-579
HAYMERSTROY,
F. N., JR. 1939 A study of Wisconsin prairie chicken and sharp-tailed grouse.
Wil. Bull., vol. 51, pp. 105-120.
HOQUE,
R. L., AND E. E. SCHNETZLER1937 Development of fertility in young Barred Plymouth Rock males. Poul. Sci., vol. 16, pp. 62-67.
KIRKPATRICK,
C. M. 1944 Body weights and organ measurements in relation to age and
season in ring-necked pheasants. Anat. Rec. in press.
C. M., AND F. N. ANDREWS 1944 Unpublished manuscript.
KIRKPATRICK,
KIRSCHBAUY,
A., AND A. R. RINGOEN 1936 Seasonal sexual activity and its experimental
modification in the male sparrow, Passer domesticus Linnaeus. Anat. Rec., vol. 64,
pp. 453-473.
PARKER,
J. E., F. F. MCKENZIE,AND H. L. KEMPSTER 1942 Development of the testes and
combs of White Leghorn and New Hampshire cockerels. Poul. Sci., vol. 21, pp. 35-44.
RIDDLE,0. 1928 Studies on the physiology of reproduction in birds. XXIII. Growth of the
gonads and bursa Fabricii in doves and pigeons, with data for body growth and age
at maturity. Am. J. Phyiol., vol. 86, pp. 248-265.
DEVELOPMENT O F THE PHEASANT TES'L'IS
ROWAN,W.
323
1929 Experinleiits in bird migration. I. M:uiipolatioii of tlic wpwduetivc cgclc :
seasonal histological cliaiiges in tlie goii;ccls. Proc. Bost. Sac., Nat. IIist., \ 01. 39,
pp. 151-208.
SCOTT,
J. W. 1942 Mating behavior of the bagc grouse. Auk. \ol. 59, 1 ~ 1 ~4i7-498.
.
WOLFSON,
A. 1942 Regulation of spring migration in juiieos. Condor, val. 44, pp. 2 3 - ! ! 6 : < .
PLATE 1
IIEVELOPMENT O F THE PIIEASAXT TESTIS
C. 11. XIKKI’ATXICK A N D N. N. ANDREWS
2 Srmiiiifrrous tubules of 3ti-day-old pheasant o n J u l y 15th contain sprrmatogonia and :I
f e w primary speiinatocytes. X 220.
3 Testis of a 109-day-oldbird on September Bth, slio\vs IIUII~CI’OUS spermatozoa. X 220.
4 Spermatogonia a n d primary speiinatocytes are present in the tubules of a 125-day-oldmale
on December 2211d. X 220.
5 Complete spermatogenesis in a 362-d:iy-old male o n May 18th. X 220.
324
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