Hormonal induction of egg production and the in-vitro
fertilization of eggs
The purpose of this experiment was to determine if B. baxteri
ovulate in response to a single mixed dose of 500 IU
hCG and 4 μg LHRHa, or if B. baxteri require a series of
doses with these hormones for the final maturation of
oocytes. The measured variables were the number of ovulating females, the number of eggs ovulated, and after invitro
fertilization the percent cleavage, neurulation and
swim-up. Swim-up is when aquatic amphibian larvae
exhaust their yolk sac and 'swim-up' to begin endogenous
feeding from their supine position.
Twenty female B. baxteri were randomly divided into two
groups of ten. One group was administered a single normally
'ovulatory' dose of 500 IU of hCG and 4 μg LHRHa
(Sigma Aldrich, St. Louis, L4513). None of these females
was induced to spawn and this group's response was considered
the unprimed control. Thereafter, this group was
considered as having one priming of 500 IU of hCG and
4 μg LHRHa combined. Seventy-two hrs later, both this
previously primed group and the group to receive one
priming, were administered an 'anovulatory' dose of 100
IU hCG and 0.8 μg LHRHa combined. This dosage is 20%
the ovulatory dose and did not induce ovulation in either
group previously having received one or no priming. After
an additional period of 96 hrs, both groups were administered
an normally ovulatory dose of 500 IU of hCG plus
4 μg LHRHa combined, after which ovulation occurred.
Consequently, prior to administration of the final ovulatory
hormone dose one group of females had received two
primings while the other group had received one priming
as shown in Table 1. All hormones were administered in
200 μl of sterile water through intra-peritoneal injection.
Individual animals were placed into single 11.4 L plastic
boxes containing 1.5 cm of Simplified Amphibian Ringers
solution to
lengthen the time the eggs would remain fertilizable. The
SAR was changed if soiling was apparent and the spawning
of eggs monitored. Eleven and half hrs after the ovulatory
dose, the first females were observed producing eggs.
The first eggs were produced between 11.5 to 12.5 hrs PA
and were collected at hourly sampling times until 24 hrs
PA. At each sampling time, a sub-sample of 100 to 150 eggs from each female were placed in one or more dry
Petri dishes. One Petri dish per male was used when fertilization
by multiple males was attempted. Approximately
100 μl of urine containing sperm samples of good motility
and concentration were pipetted onto the egg string,
the eggs and sperm mixed and then left for 10 minutes
before flooding the dishes with water.
Fertilization rates were assessed as the percentage of
cleaved eggs at larval stage 3 to 6 [28] from 6 to 8 hrs after
the application of sperm to the eggs. Counts of cleaved
eggs and unfertilized eggs were taken using a stereo dissecting
microscope (Omano™) and the percent cleavage
was calculated. Two indices of egg/embryo quality were
used: 1) the percentage of eggs reaching neurulation, larval
stage 26–28 [28]; and 2) the percentage of embryos
reaching 'swim-up' (endogenous feeding, larval stage 44–
46) [28]. After conclusion of the experiments, tadpoles
were released to the U.S. Fish and Wildlife Service as part
of the B. baxteri reintroduction program.
เหนี่ยวนำฮอร์โมนไข่ผลิตและในเครื่องการปฏิสนธิของไข่วัตถุประสงค์ของการทดลองนี้เป็นการ กำหนดว่าถ้าเกิด baxteriovulate การผสมปริมาณเดียวของ 500 IUของ hCG และ 4 μg LHRHa หรือ ถ้า baxteri เกิดต้องใช้ชุดของปริมาณ มีฮอร์โมนเหล่านี้สำหรับพ่อแม่ที่สุดท้ายของแช่สารละลาย ตัวแปรที่วัดมีจำนวนเพศหญิง ovulating จำนวนไข่ ovulated และ หลัง invitroปัจจุบันปริเปอร์เซ็นต์ neurulation และสระว่ายน้ำ สระว่ายน้ำเป็นเมื่อตัวอ่อนสัตว์น้ำ amphibianท่อไอเสียแดง sac และ 'สระว่ายน้ำ' ประเดิม endogenous ของพวกเขาอาหารจากตำแหน่งของ supine20 baxteri เกิดหญิงถูกสุ่มแบ่งออกเป็นสองกลุ่มสิบ กลุ่มหนึ่งดูแลเดียวตามปกติพื้นที่ซึ่งมีทั้ง 500 IU ของ hCG และ 4 μg LHRHa 'คะ'(ซิก Aldrich, St. Louis, L4513) หญิงเหล่านี้ไม่มีถูกทำให้เกิดการวางไข่นี้ถือเป็นการตอบสนองของกลุ่มตัวควบคุม unprimed หลังจากนั้น กลุ่มนี้ได้ถือว่าเป็นมีด้วยหนึ่งของ 500 IU ของของ hCG และ4 μg รวม LHRHa เจ็ดสองชั่วโมงต่อมา ทั้งนี้ก่อนหน้านี้ งเยียกลุ่มและกลุ่มได้รับปั๊ม มีจัดการพื้นที่ซึ่งมีทั้ง 'anovulatory' 100ของ IU hCG และ 0.8 μg LHRHa รวม ขนาดนี้เป็น 20%ยาคะ และไม่ก่อให้เกิดการตกไข่ในกลุ่มมีได้รับก่อนหน้านี้ หนึ่ง หรือด้วยไม่ หลังจากรอบระยะเวลาเพิ่มเติมของ 96 น. ทั้งกลุ่มได้รับการดูแลยาผิดปกติคะของ 500 IU ของบวกของ hCG4 μg LHRHa combined, after which ovulation occurred.Consequently, prior to administration of the final ovulatoryhormone dose one group of females had received twoprimings while the other group had received one primingas shown in Table 1. All hormones were administered in200 μl of sterile water through intra-peritoneal injection.Individual animals were placed into single 11.4 L plasticboxes containing 1.5 cm of Simplified Amphibian Ringerssolution tolengthen the time the eggs would remain fertilizable. TheSAR was changed if soiling was apparent and the spawningof eggs monitored. Eleven and half hrs after the ovulatorydose, the first females were observed producing eggs.The first eggs were produced between 11.5 to 12.5 hrs PAand were collected at hourly sampling times until 24 hrsPA. At each sampling time, a sub-sample of 100 to 150 eggs from each female were placed in one or more dryPetri dishes. One Petri dish per male was used when fertilizationby multiple males was attempted. Approximately100 μl of urine containing sperm samples of good motilityand concentration were pipetted onto the egg string,the eggs and sperm mixed and then left for 10 minutesbefore flooding the dishes with water.Fertilization rates were assessed as the percentage ofcleaved eggs at larval stage 3 to 6 [28] from 6 to 8 hrs afterthe application of sperm to the eggs. Counts of cleavedeggs and unfertilized eggs were taken using a stereo dissectingmicroscope (Omano™) and the percent cleavagewas calculated. Two indices of egg/embryo quality wereused: 1) the percentage of eggs reaching neurulation, larvalstage 26–28 [28]; and 2) the percentage of embryosreaching 'swim-up' (endogenous feeding, larval stage 44–46) [28]. After conclusion of the experiments, tadpoleswere released to the U.S. Fish and Wildlife Service as partof the B. baxteri reintroduction program.
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