The Journal of Zoology Studies
Vol. 3 No. 6 2016 Journalofzoology.com
Page 45
The Journal of Zoology Studies 2016; 3(6): 45-55
ISSN 2348-5914
JOZS 2016; 3(6): 45-55
JOZS © 2016
Received: 22-12-2016
Accepted: 27-02-2017
Deepak Kumar Singh
Department of Zoology, Govt.
Autonomous College, Rourkela-
769004, India.
Nakulananda Mohanty
Department of Zoology, North
Orissa University, Baripada-757003,
Odisha, India.
Nirakar Jena
P.G. Department of Life Sciences,
Govt. Autonomous College,
Phulbani-762001, India.
Corresponding Author:
Nakulananda Mohanty
Department of Zoology, North
Orissa University, Baripada-757003,
Odisha, India.
Reproductive cycle of male common Indian rock lizard,
Psammophilus blanfordanus: Seasonal testis, epididymis and
renal sex segment histology
Authors: Deepak Kumar Singh, Nakulananda Mohanty, Nirakar Jena
Abstract
Research on reproduction of male Psammophilus blanfordanus, the common Indian rock lizard
(Reptilia: Diapsida: Agamidae) is scanty and no report in available regarding relationship
between environmental factors and its reproductive status. To understand this relationship,
studies on gonadosomatic index (GSI), histology and histometry of testis, epididymis and renal
sex segment (RSS) were undertaken. The relative weight of testis (RTW), epididymis (REW),
vas deferens (RVW) and kidney (RKW) are highest during breeding season. The RTW and
REW are positively correlated with temperature, rainfall and relative humidity (RH). The
histology and histometry of testis, epididymis and RSS indicate that the breeding season in this
animal is from April to June/ July to early August. During this period the diameter and epithelial
cell height of seminiferous tubules, epididymis and RSS tubules are increased along with the
increase in the diameter of Leydig cell nucleus. Density of testicular and epididymal sperms,
and RSS tubular contents are also increased. This study will enrich the knowledge on
environmental control of reproduction, and the animal’s reproductive adaptation during
vertebrate evolution.
Keywords: Reptilia, Diapsida, Agamidae, male P. blanfordanus, testis, renal sex segment
1. Introduction
Reproductive activity in reptiles is mostly seasonal and restricted to a few months of a year.
Majority of the temperate zone species of lizards are seasonal breeders and breed during the
early summer followed by a sexual quiescence from late summers through fall or breed during
the late summer through fall [1]
. However, many tropical lizard species breed during the late
summer with a quiescent phase during winter or spring, and some of the tropical species breed
throughout the year [1]
. Studies on testicular cycle of tropical lizard species indicate that
spermatogenic patterns are peculiar to each species. Many tropical species of male lizards
exhibit continuous spermatogenic cycle with little or no evidence of variations in the testicular
[2] or seminiferous tubule
[2, 3] size. Others undergo cyclic changes in their testicular mass
[4]. The
spermatogenic cycles are generally distinguished into three phases, viz. recrudescence or pre-
breeding, breeding and quiescence or post-breeding phases. The enlargement and regression of
seminiferous tubules correlate with the testicular activity [5]
. The epididymis of lizards is simple
and convoluted tubules and its size is correlated with Leydig cell activity, i.e., androgen
dependent [6, 7, 8]
.
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The posterior segment of the kidney is called as renal
sex segment (RSS) is a unique nephric region found
only in male lizards and snakes. It becomes swollen
during the breeding season and contributes to the
seminal fluid [9]
. The RSS in lizards is a secondary sex
organ as these segments behave as that of the prostate
of mammals [10]
. The production of some chemical
compounds from RSS causes cloacal plug in female
making it unreceptive to other males [11]
.
The relationship between reproductive cycle and
climate suggests that reproduction in lizards is affected
by ambient temperature [12, 13]
, precipitation [14, 15]
and
photoperiod [16]
. Extensive works have been done on
Anolis sps. as a temperate region animal model, while
Calotes versicolor in the most sought after species in
the tropical region. Data on Indian lizards for
reproduction is scanty, except some studies on the most
common agamid, Calotes nemericola [17]
, C. versicolor [18,19,20,21]
, Psammophilus dorsalis [22,23]
, Mabuya
sps.[7,24,25,26,27,28]
, geckos [29,30,31,32]
. However, little
scientific knowledge exist about the reproductive
biology of the common Indian rock lizard,
Psammophilus blanfordanus, a tropical Agamidae
(Reptilia: Diapsida), as only brief reproductive period
of this lizard from April to June based on classical
studies is reported [33]
. Therefore, an attempt has been
made to investigate the reproductive cycle of this
tropical lizard by assessing the gonadosomatic index
(GSI); and correlation between relative weights of
testis and its associated reproductive organs and
temperature, rainfall and humidity. Further, a detailed
histology and histometry of the above tissues were also
performed in each month to know the reproductive
status of this animal during different phases so that its
evolutionary adaptability will be judged, and will be
helpful in studying comparative vertebrate phylogeny.
2. Materials and Methods
2.1 Animals
As the animals are active during early morning hours,
they were collected in that period from Baripada,
Mayurbhanj, Odisha (21º 6′ and 22º 34′ N and 85º 40′
and 87º 11′ E) and adjoining areas. After capture, the
animals were brought to the laboratory. Sexually
mature lizards were considered for the study. Sexual
maturity of the animal was assessed by the method of
Pradhan [34]
. The lizards were acclimatised at least for
15 days to laboratory conditions by keeping them in
clean wire-mess cages and fed with insects. Water was
provided ad libitum to the animals. Since sexual
dimorphism is prevalent, the animals were tentatively
sexed by examining relative head width, body size and
shape. Males have relatively broader head, distinct
tympanum and presence of keeled scales, stoutly build
and brightly coloured. Sex was confirmed by visual
examination of the cloacal opening for the presence or
absence of hemipenis musculature which is virtually
the main criterion to ascertain sex in non-breeding
season. A minimum of 5-9 mature animals were
collected for each month to ascertain its reproductive
cycle.
2.2 Morphology and morphometry of animals
Each specimen was weighed to nearest 0.01g with
spring scale (Persola). The snout to vent length (SVL)
and tail length (TL) to nearest 0.1mm were determined
using digital caliper (Mitutoyo). After that the animals
were decapitated and dissected to obtained
reproductive and accessory reproductive organs which
were weighed to nearest 0.001g with monopan balance
(Shimazdu). Analyses of the organ weight have been
based on somatic indices (mg/100 g body wt.) to
reduce variability due to body weight. Gonadosomatic
index (GSI) was calculated as: gonad weight/body
weight x 100.
2.3 Assessment of spermatogenic activity Quantitative assessment was used to determine the
stage of spermatogenic activity as per Shanbhag et al. [32]
. Based on the occurrence and density of
spermatogenic cells, the testicular activity was
categorised into four stages. Stage-I: With
spermatogonia, primary and secondary spermatocytes;
Stage-II: All stages of spermatogenesis but with a few
spermatids and sperms; Stage-III: All stages of
spermatogenesis with moderate quantities of
spermatids and sperms; and Stage-IV: All stages of
spermatogenesis with abundant spermatids and sperms.
2.4 Histology and histometry of sex organs
The testis, epididymis, vas deferens and kidney (for
study of RSS) were dissected out, freeing them from
the adhering tissues and were fixed in Bouin’s fluid
(except vas deferens) for histological studies. The
diameters of seminiferous tubule (ST) and Leydig cell
nucleus (LN), and height of germinal epithelium (GH)
were measured by ocular micrometer. Histometry was
also done for epididymis and kidney. These were
measured to know probable seasonal changes in the
testis and epididymis.
The occurrence and density of testicular and
epididymal spermatozoa, and contents of lumen of RSS
tubule were visualised (blind test) and graded from
minimum or nil (-) to the maximum (++++) and the
mean for monthly sample was then computed.
2.5 Meteorology
The average data regarding maximum and minimum
temperature, rainfall and relative humidity (RH) of
each month for entire study period of Baripada were
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collected from the state Meteorology Department
stationed at Baripada in the district of Mayurbhanj,
Odisha.
2.6 Statistical analyses
Linear regression and coefficient of correlation were
calculated [35]
by taking meteorological data
(temperature, rainfall and relative humidity) as
independent variable with that of the relative weight of
the testis and epididymis as dependent variable. The
coefficient of variation (CV) was also calculated for
lengths of different body parts [35]
.
Table 1: Seasonal variation in the snout to vent length (SVL), tail length (TL) and total length (ToL) and body
weight (BW) of male P.blanfordanus. Unit of measurement is given in parentheses. Data are mean ± standard
deviation.
Month Number of
animals (9) SVL (cm) TL (cm) ToL (cm) BW (g)
January 6 9.97±0.23 17.33±0.88 27.30±1.02 47.33 ± 2.870
February 9 10.23±0.40 17.90±1.27 28.13±1.31 48.17 ± 2.407
March 5 10.05±0.16 19.07±0.82 29.12±0.89 46.89 ± 2.407
April 5 9.90±0.22 16.99±0.69 26.89±0.80 46.76 ± 2.773
May 7 9.93±0.18 18.14±1.29 28.07±1.27 47.57 ± 2.181
June 7 10.04±0.11 17.29±0.93 27.33±0.85 47.14 ± 1.621
July 7 9.89±0.13 16.80±0.76 26.69±0.82 47.43 ± 2.541
August 8 9.87±0.16 17.51±0.70 27.39±0.74 47.10 ± 1.446
September 9 9.84±0.17 17.87±0.85 27.71±0.95 47.95 ± 2.147
October 9 9.93±0.16 17.37±1.00 27.30±1.07 47.60 ± 1.635
November 8 10.03±0.29 18.56±0.68 28.59±0.82 46.71 ± 3.757
December 7 10.01±0.30 18.17±1.08 28.19±1.24 47.00 ± 2.055
3. Results
3.1 Morphology and morphometry of animal
The snout to vent length (SVL) ranged from 9.5 to 10.5
cm (mean = 9.97cm) and coefficient of variation (CV)
was 2.12; the tail length (TL) was more than that of
SVL and ranged from 16.00 - 20.00 cm (mean = 17.75
cm and CV = 5.13); the total body length (ToL) ranged
from 25.5 to 30.5 cm (mean = 27.72 cm and CV = 3.5)
and the body weight ranged from 42 to 50 g (Table 1).
The gonadosomatic index (GSI) was lowest during
December (0.032) which increased gradually reaching
the peak in July (1.40) (Table 2).
Table 2: Seasonal variation in the gonadosomatic index (GSI), relative testicular weight (RTW), relative epididymis
weight (REW), relative vas deferens weight (RVW), relative kidney weight (RKW) of male, P.blanfordanus. Unit
of measurement is given in parentheses. Data are mean ± standard deviation.
Month
Number of
animals
(n)
GSI RTW
(mg)
REW
(mg)
RVW
(mg)
RKW
(mg)
January 6 0.054±0.007 54.46±6.91 18.99 ± 4.82 16.27±3.96 388.23±33.35
February 9 0.307±0.049 306.96±49.37 50.54 ± 11.04 36.57±5.07 553.82±62.22
March 5 0.617±0.043 617.14±42.62 91.96 ± 35.39 61.82±6.54 549.09±66.74
April 5 0.909±0.109 909.28±109.00 98.93 ± 17.66 60.64±6.12 431.23±30.51
May 7 1.060±0.065 1060.17±65.40 174.51 ± 10.37 75.10±10.57 555.59±81.76
June 7 1.000±0.130 1000.20±130.22 185.82 ± 15.91 93.44±12.24 536.57±57.62
July 7 1.408±0.080 1408.38±80.30 192.59 ± 20.12 112.73±12.06 715.94±67.49
August 8 0.648±0.135 648.30±135.44 121.01 ± 22.35 81.18±8.65 499.79±15.66
September 9 0.162±0.045 162.01±44.60 81.62 ± 17.07 54.44±7.94 507.31±47.74
October 9 0.081±0.015 80.68±15.37 45.01 ± 15.81 32.73±7.17 457.23±30.35
November 8 0.052±0.026 52.31±25.64 27.79 ± 6.77 19.18±9.21 441.60±90.53
December 7 0.032±0.015 32.25±15.00 15.33 ± 4.13 17.43±3.45 361.54±40.35
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3.2 Histology and histometry
3.2.1 Testis
The size and weight of the left and right testes were
similar. The testis appeared whitish from October to
February / March (non-reproductive phase) and
yellowish from April to July/August (reproductive
phase) during which they were highly vascularised.
The weight of the testis decreased from August to
December (about 24.47%) and the weight gradually
increased to about 21.80% in March and 46.03% in
July in comparison to December. However, the
maximum relative weight of testis was observed in July
(1,408.38 ± 80.30 mg) (Table 2). The testis appeared to
be swollen during June and July as evidenced from
cross-sectional diameter of the testis (6.47 ± 4.17 mm
and 6.41 ± 3.08 mm for June and July, respectively).
After July, the testis size decreased and reached lowest
value in December (1.65 ± 3.13 mm) and January (1.62
± 1.66 mm) (Table 3).
The decrease or increase of the diameter of the
seminiferous tubules and its epithelial cell height
showed similar pattern with that of the testis diameter
(Table 3). The sperms were observed in the lumen of
the seminiferous tubules from March to October with
peak in June and July (Table 3). With the increase in
the process of spermatogenesis, there was
corresponding increase in the size of the Leydig cell
along with its nucleus. The increase in Leydig cell
nuclear diameter was started from February (4.31 ±
0.31 μm) and it reached maximum size in July (5.44 ±
0.06 μm) (Table 3). The decreasing tendency of the
nuclear diameter was observed from October (3.88 ±
0.86 μm) to January (3.79 ± 0.09 μm) (Table 3).
Table 3: Seasonal variation in the testicular histometry: Diameter of testis section, diameter of seminiferous tubule,
seminiferous epithelium height, Leydig cell nuclear diameter and density of testicular sperm of male
P.blanfordanus. Unit of measurement is given in parentheses. Data are mean ± standard deviation.
Month
Testis
section
diameter
(mm)
Diameter of
seminiferous
tubules
(µm)
Seminiferous
epithelium
height
(µm)
Leydig cell
nuclear
diameter
(µm)
Density of
testicular
sperm
January 1.62±1.662 95.82±1.662 29.82±1.601 3.79±0.099 -
February 2.15±1.401 166.82±1.401 44.64±2.063 4.31±0.312 -
March 3.65±3.219 202.82±3.219 69.73±2.328 4.40±0.039 +
April 5.53±2.803 232.64±2.803 83.18±2.822 4.97±0.170 ++
May 5.84±2.663 257.09±2.663 87.55±3.012 5.08±0.172 +++
June 6.47±4.178 272.64±4.178 89.00±3.435 5.23±0.091 ++++
July 6.41±3.081 240.91±3.081 73.09±2.427 5.44±0.062 ++++
August 4.85±2.501 232.36±2.501 63.91±3.113 4.75±0.086 +++
September 3.78±4.154 142.64±4.154 44.27±4.268 4.50±0.081 ++
October 2.58±4.132 106.55±4.132 16.55±2.018 3.88±0.860 +
November 1.99±2.252 97.55±2.252 15.36±1.912 3.85±0.081 -
December 1.65±3.133 89.73±3.133 14.55±3.560 3.80±0.020 -
‘-‘= Absent; ‘+’ = Present.
3.2.2 Epididymis and vas deferens
Epididymis and vas deferens underwent marked
seasonal variation in size, weight and also histology of
epididymes as that of the testicular activities. Similar to
testis weight, the maximal relative weight of the
epididymis (192.59 ± 20.12 mg) and the vas deferens
(112.73 ± 12.06 mg) was observed in July (Table 2). In
the same pattern, lower value was observed in
December for epididymis (15.33 ± 4.13 mg) and vas
deferens (17.43 ± 3.45 mg) (Table 2). The diameter,
epithelial cell height and sperm density of epididymis
showed similar pattern as that of the testis throughout
the year (Table 4).
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Table 4: Seasonal variation in the epididymal histometry: Diameter of epididymal tubule, epididymal epithelium
height and density of epididymal sperm of male P.blanfordanus. Unit of measurement is given in parentheses. Data
are mean ± standard deviation.
Month
Diameter of
epididymal tubules
(µm)
Epididymal epithelium
height (µm)
Density of epididymal
sperm
January 94.2±4.6 24.8±1.6 -
February 120.8±8.7 35.4±3.0 -
March 209.5±6.0 44.1±3.0 +
April 245.0±7.2 48.2±1.8 ++
May 252.7±5.4 50.7±1.8 +++
June 247.2±6.2 62.0±2.6 ++++
July 241.1±2.2 65.4±1.0 ++++
August 235.3±5.8 55.4±2.9 +++
September 191.8±6.0 45.7±1.2 ++
October 130.2±3.0 23.5±1.8 +
November 100.7±3.0 22.2±0.7 -
December 91.3±4.4 20.4±0.8 -
‘-‘ = Absent; ‘+’ = Present.
3.2.3 Kidney and renal sex segment (RSS)
Maximum relative weight of kidney was in July
(715.94 ± 67.49 mg) and minimum in December
(361.54 ± 40.35 mg) (Table 2). The diameter of the
kidney remained slightly higher from April to
September than the other months of the year which was
also more or less same (Table 5). The diameter of the
RSS tubules increased gradually from February (101.5
± 2.5 μm) to July (187.8 ± 7.5 μm) and August (188.1
± 10.8 μm) (Table 5). Similarly, the height of the
epithelium also increased from March (21.7 ± 1.7 μm)
to July (38.7 ± 4.5 μm) (Table 5). The RSS tubules
were sparse and inconspicuous during December and
January, and gradually became more elaborate and
prominent from February. The tubular epithelium
hypertrophied, became columnar and secretory by
April. The secretory granules were observed from
April to August. Sperms were also observed inside the
lumen. A dramatic decrease in the lumen secretion in
RSS tubules occurred by the end of September (Table
5).
Table 5: Seasonal variation in the RSS histometry: Diameter of kidney, diameter of RSS tubule, RSS epithelium
height and contents of RSS tubule lumen of male P. blanfordanus. Unit of measurement is given in parentheses.
Data are mean ± standard deviation.
Month
Diameter of
kidney
(mm)
Diameter of RSS
tubule
(µm)
RSS epithelium
height (µm)
Contents of
RSS tubule
lumen
January 2.5±0.3 82.0±3.4 16.5±1.7 -
February 2.7±0.2 101.5±2.5 17.2±1.4 -
March 2.8±0.1 120.6±1.7 21.7±1.7 +
April 3.3±0.2 128.5±2.0 26.2±3.6 ++
May 3.8±0.2 160.5±3.4 30.0±3.6 +++
June 3.9±0.2 185.2±8.0 32.6±5.9 +++
July 3.7±0.2 187.8±7.5 38.7±4.5 ++++
August 3.5±0.4 188.1±10.8 28.8±3.5 +++
September 3.3±0.2 128.4±8.9 20.4±4.4 +
October 2.6±0.2 108.3±6.7 16.1±1.7 -
November 2.4±0.2 88.4±3.4 15.2±3.6 -
December 2.2±0.2 88.3±6.8 15.1±2.1 -
‘- = Absent; ‘+’ = Present.
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Fig 1A: Coefficient of correlation and regression analysis between temperature and relative testicular weight (RTW)
of male P. blanfordanus.
Fig 1B: Coefficient of correlation and regression analysis between rainfall and relative testicular weight (RTW) of
male P. blanfordanus.
Fig 1C: Coefficient of correlation and regression analysis between relative humidity and relative testicular weight
(RTW) of male P. blanfordanus.
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Fig 2A: Coefficient of correlation and regression analysis between temperature and relative epididymis weight
(REW) of male P. blanfordanus.
Fig 2B: Coefficient of correlation and regression analysis between rainfall and relative epididymis weight (REW) of
male P. blanfordanus.
Fig 2C: Coefficient of correlation and regression analysis between relative humidity and relative epididymis weight
(REW) of male P. blanfordanus.
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3.3 Correlation with meteorology It was observed that the relative weight of the testis
(RTW) and epididymis (REW) showed a significant
(P<0.001) positive correlation with temperature
(Figures 1A and 2A) and rainfall (P<0.01; Figures 1B
and 2B). Through there was positive correlation of
RTW (Figure 1C) and REW (Figure 2C) with relative
humidity (RH), it was not significant.
4. Discussion
The precise indicators of reproductive status of lizards
are said to be not one, but a combination of epididymis,
vas deferens, RSS and spermatogenic stages of the
testis. Almost all investigators rely on the weight of the
testis as an indicator of reproductive status of animal.
Testis weight would, however, be a good indicator of
male reproductive cycle [36]
. The reproductive status of
the animal under consideration, P. blanfordanus, has
been determined using weight of RSS, testis,
epididymis and vas deferens during different months of
the year. The data indicate that this lizard exhibits a
distinct circannual rhythm with a well defined seasonal
testis cycle which can be considered under three
phases. The gradual increase in these parameters from
February to March may be called as phase of
recrudescence (pre-breeding period); more or less
similar values from April to July/August as phase of
reproduction (breeding period). Then gradual decrease
from late August to January may be called as phase of
quiescence or regression (post-breeding period).
Similar cyclical changes in testicular mass have been
reported for other tropical lizards [3, 37, 38]
. Further, it has
been reported that testis weight reduction indicates
reduced sperm production [38]
.
The variation in weight of the testis is reflected in
corresponding changes in the histological parameters
and spermatogenic activity of the testis (Table 3). The
peak spermatogenic activity was observed during
breeding period (April-July/early August). The post-
nuptial regression of testis and its accessory
reproductive organs starts from late August and
becomes sexually inactive by early September. Since,
hibernation is observed during the cold months (late
November to early February), the process of
spermatogenesis is halted. This pattern of seasonal
reproduction among other temperate [1]
and tropical [3]
lizards has been reported. When the environment is
conducive and temperature is nearly constant without
cold season, the reptiles show continuous reproduction,
i.e., spermatogenesis and other spermatogenic
processes continue throughout the year [1, 15]
.
The accessory reproductive organs of lizards, like RSS,
epididymis and vas deferens are androgen dependent [39, 40]
. The androgen dependence has been proved in
castrated lizards [7, 40]
. The reptilian epididymis is
similar with respect to ultrastructure and function of
mammalian epididymis [22, 41]
. The epididymis of P.
blanfordanus may be divided into three regions, i.e.,
anterior, middle and posterior as reported for P.
dorsalis [6]
, Mabuya carinata [42]
and H. flaviviridis [31]
.
On the other hand, it has five regions in C. versicolor [43]
and four divisions in Sitana ponticeriana [44]
. The
reptilian epididymis is known to undergo changes in
structure in relation to testicular cycle [22, 42, 45, 46]
.
Similarly, histometric changes in the epididymis, like
diameter and epithelial cell height of epididymis and its
sperm density (Table 4) show seasonal variations like
that of its testis. The diameter and epithelial cell height
of the epididymis reached its maximum size at the
reproductive phase (April-July/August) and started to
regress from September to January before recovery
begins in February. Seasonal change in epididymal
tubule diameter and epithelial height has been reported
for the lizard, Agama agama agama [3]
.
The histomorphology of the renal sex segment (RSS)
in P. blanfordanus is comparable with those of other
lizards, such as C. versicolor [10]
and P. dorsalis [47]
.
The RSS are recognised to be sexually dimorphic in
structure representing the hypertrophied collecting
ducts of the kidney present at the caudal end [5]
. The
RSS can include the terminal segment of the distal
convulated tubule (DCT), post-terminal segment,
collecting duct and/or portion of ureter [48, 49]
. In the
case of P. blanfordanus, the RSS is found at the caudal
end of the kidney. The diameters of kidney and RSS
tubules and epithelial cell height of RSS along with its
secretions are more in reproductive phase (Table 5).
These are generally found in the sexually active male
snakes and lizards [49, 50]
and indistinguishable from the
adjacent tubular region during the sexual quiescence.
The RSS undergoes hypertrophy and becomes
secretory during the breeding season and involutes in
non-breeding season. The RSS has been studied in H.
faviviridis, C. versicolor [22, 29]
, Scincella laterale [51]
and H. turcicus [52]
and in snakes, like Natrix natrix [53]
,
Seminatrix pygaea [54]
and Agkistrodon piscivorous [55]
.
The RSS is more extensive in lacertids than those of
other lizards [51]
.
The actual functions of RSS still remain mystery but its
secretion may sustain and activate the sperms. It is
suggested that the secretion of RSS besides sustaining
sperms it contributes a physical medium for sperm
transport, prevents desiccation and facilitates the
movement of sperm along the groove of the hemipenis [22, 56, 57, 58]
, provides courtship pheromones [59]
and
forms copulatory plugs [60]
. Weil [61]
suggested that the
RSS secretion of the snake, Nerodia sipendon has dual
functions: one is of sperm transport and capacitation in
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the female reproductive tract and the other is related to
sexual behaviour. Interpreting the reproductive cycle of
squamate becomes impossible without taking into
account the secretory cycle of RSS, as RSS is essential
for mating. There exist a homology between reptilian
RSS and mammalian seminal vesicle since both share
certain common features, like embryological origin,
relationship with vas deferens and response to
androgen [58]
.
Environmental variables, like temperature, rainfall etc.
have been implicated in timing the onset of
reproduction and also its termination [13, 15]
. Licht [62]
described temperature as the single most important
factor and it is the only factor involved in
synchronisation of the annual reproductive cycle in
lizards. Rainfall reported to influence egg lying and it
is not considered to be primary cue on the testicular
cycle. This phenomenon has been reported in C.
versicolor [22]
.
5. Conclusion
Reproduction in this animal is influenced by the
climatic conditions of the habitat. The correlation
studies of relative testicular weight (RTW) and
epididymis weight (REW) with that of temperature,
rainfall and humidity (Figures 1A-C and 2A-C) on this
animal indicate that so far as the impact of these
environmental factors are concerned, the temperature
comes first, then rainfall and lastly the humidity. This
male tropical lizard has breeding period from April to
June/July and at times extends to early August, post-
breeding period or quiescence from late
August/September to December/ January and pre-
breeding period or recrudescence is from
January/February to March. Histological studies on
female sex organs of this species (unpublished personal
observation) show similar breeding seasons. Therefore,
the reproductive cycle of this animal is ‘associated’
type (as there is synchrony between reproductive
cycles of male and female) as reported for other lizards [2, 4, 63]
.
6. Acknowledgements
The authors are thankful to the Head of the Department
for providing necessary laboratory facilities. Thanks
are also due to financial assistance to Dr. D.K. Singh
from UGC under RGNF.
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