Characterization of fetal growth by repeated ultrasound measurements in the wild guinea pig (Cavia aperea)

Fetal growth during pregnancy has previously been studied in the domesticated guinea pig (Cavia aperea f. porcellus) after dissecting pregnant females, but there are no studies describing the fetal growth in their wild progenitor, the wild guinea pig (C aperea). In this study, 50 pregnancies of wild guinea pig sows were investigated using modern ultrasound technique. The two most common fetal growth parameters (biparietal diameter [BPD] and crown-rump-length [CRL]) and uterine position were measured. Data revealed similar fetal growth patterns in the wild guinea pig and domesticated guinea pig in the investigated gestation period, although they differ in reproductive milestones such as gestation length (average duration of pregnancy 68 days), average birth weight, and litter mass. In this study, pregnancy lasted on average 60.2 days with a variance of less than a day (0.96 days). The measured fetal growth parameters are strongly correlated with each (R = 0.91; P < 0.001) other and with gestational age (BPD regression equation y = 0.04x − 0.29; P < 0.001 and CRL regression equation y = 0.17x − 2.21; P < 0.01). Furthermore, fetuses in the most frequent uterine positions did not differ in their growth parameters and were not influenced by the mother ID. Our results imply that ultrasound measurement of a single fetal growth parameter is sufficient to reliably estimate gestational age in the wild guinea pig.     

Estimation of gestational ages in the common marmoset (Callithrix jacchus) from published prenatal growth curves

This report compares estimated gestational ages from published cubic spline curves to gestational ages estimated retrospectively from delivery dates in 28 pregnancies from ten common marmosets (Callithrix jacchus). Both CRL- and BPD-based estimates of gestational age were closely correlated with delivery-based gestational age estimates. Of the three ultrasound machines used, the one with 16 shades of gray and a sequential linear array overestimated gestational age during early pregnancy, based on CRL measures. Measures from the other two machines (64 or 264 shades of gray; linear sector and annular array or electronic phase array) were similar and resulted in a correlation of the two estimates of gestational age of 0.94 and a mean difference between the two estimates of 0.16 days with 80% of CRL-based gestational age estimates being within ± 5 days of the delivery-based estimate. The reliability of BPD-based estimates of gestational age was strongly related to pregnancy outcome. BPD-based estimates underestimated gestational age in poor outcome pregnancies (i.e., those in which infants died within 7 days of birth) but not in good outcome pregnancies. The combined CRL- and BPD-based estimates on poor outcome pregnancies suggest that there was less growth in BPD in late gestation for those pregnancies that resulted in nonviable offspring. For good outcome pregnancies, the correlation between BPD-based and delivery-based estimates of gestational age was 0.871 and the mean difference between the two estimates was ?0.06 days with 83.3% of BPD-based estimates falling within ± 5 days of delivery-based estimates.     

Ultrasound diagnosis of mouse pregnancy and gestational staging

Phenotypic analysis of mutant mice is limited by lack of accurate, simple, and nondestructive in utero imaging techniques. This study evaluated the usefulness of ultrasound imaging (US) to stage fetal mouse gestational age (GA) and depict morphologic development. We imaged 16 pregnant CD-1 mice and a total of 92 fetuses with a 15-MHz US transducer from 9.5 d postcoitus (DPC) until 20.5 DPC or delivery. Parameters recorded included gestational sac dimensions, crown-rump length (CRL), biparietal diameter (BPD), thoracoabdominal diameter (TAD), onset of cardiac activity, and morphologic development. At 9.5 d DPC, all gestations appeared as rounded sacs, with a diameter (mean +/- standard error) of 4.4 +/- 1 mm. BPD, CRL, and GA were highly correlated. The following structures were first identifiable at the following GA: cardiac activity, 10.5 DPC; major cardiovascular structures, 11.5 DPC; limb buds, 10.5 DPC; spine, 12.5 DPC; face and skull ossification, 13.5 DPC; rib ossification, 15.5 DPC; hind- and forelimb digits, 15.5 DPC; stomach and urinary bladder, 17.5 DPC; visualization of the rhombencephalic vesicle, 13.5 DPC; and visualization of the lateral ventricles, 14.5 DPC. The echogenic lungs were distinct from the liver as early as 12.5 DPC. The circle of Willis was detectable with color Doppler as early as 13.5 DPC and was easily visualized at 15.5 DPC. We found that US provides accurate, simple staging criteria for fetal mouse gestational development after 9.5 DPC and may be a nondestructive means of documenting phenotypic alterations in mutant mice in utero.     

Ultrasonographic monitoring of fetal development in unrestrained bonobos (Pan paniscus) at the Milwaukee County Zoo

The bonobo, Pan paniscus, is one of the most endangered primate species. In the context of the Bonobo Species Survival Plan^®, the Milwaukee County Zoo established a successful breeding group. Although the bonobo serves as a model species for human evolution, no prenatal growth curves are available. To develop growth graphs, the animals at the Milwaukee County Zoo were trained by positive reinforcement to allow for ultrasound exams without restraint. With this method, the well being of mother and fetus were maintained and ultrasound exams could be performed frequently. The ovulation date of the four animals in the study was determined exactly so that gestational age was known for each examination. Measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) were used to create growth curves. Prenatal growth of P. paniscus was compared with the data of humans and the common chimpanzee, P. troglodytes. With respect to cranial structures, such as BPD and HC, humans have significant acceleration of growth compared with P. paniscus and P. troglodytes. In P. paniscus, growth of AC was similar to HC throughout pregnancy, whereas in humans AC only reaches the level of HC close to term. Growth rate of FL was similar in humans and the two Pan species until near day 180 post‐ovulation. After that, the Pan species FL growth slowed compared with human FL. The newly developed fetal growth curves of P. paniscus will assist in monitoring prenatal development and predicting birth dates of this highly endangered species. Zoo Biol 30:241–253, 2011. © 2010 Wiley‐Liss, Inc.     

Maternal care and infant development in <Emphasis Type="Italic">Callimico goeldii</Emphasis> and <Emphasis Type="Italic">Callithrix jacchus</Emphasis>

Callimico goeldii gives birth to single offspring, whereas other callitrichids, including Callithrix jacchus, twin. This study compares maternal effort and infant development in C. goeldii and C. jacchus; it is the first study to look at nursing frequency. Infants were observed from birth for 7 weeks in two captive groups each of C. goeldii and C. jacchus. C. goeldii mothers physiologically invested the same or less than C. jacchus mothers. C. goeldii mothers gained the same amount of weight during pregnancy in absolute terms as did the smaller C. jacchus. This results in a smaller gain in proportion to maternal weight but an equivalent proportional gain on a per fetus basis. C. goeldii mothers nursed their infants less based on duration of nursing bouts compared with C. jacchus mothers. C. goeldii mothers transported their infants exclusively through the first 2 weeks of life, which is longer than C. jacchus mothers, who exclusively transported infants only during the first week of life. As maternal infant carriage declined, other group members transported offspring in both species. C. goeldii infants engaged in independent locomotive sequences later in development and tasted solid foods less frequently than C. jacchus infants when compared at equivalent ages. A single, opportunistic milk sample obtained from a C. goeldii mother when her infant was 48 days old indicates that C. goeldii milk contains gross energy from crude protein within the range of variation observed in Callithrix milk. Despite the similarities in milk quality and prenatal effort in individual fetuses, C. goeldii infants gain weight faster from 0 to 18 months than do C. jacchus infants. A reduction in litter size allows C. goeldii mothers to spend more time carrying their infant and to delay weaning, thereby allowing accelerated infant and juvenile growth rates compared with C. jacchus.     

Breed differences in biparietal diameters of second trimester Toggenbubrg, Nubian and Angora goat fetuses

Seven purebred Toggenburg fetuses in four does, six purebred Nubian fetuses in four does, and eight Angora fetuses in six does were repeatedly measured using transabdominal real-time ultrasound with a 5 MH(z) linear-array transducer from 40 d to 100 d gestational age (GA) and their biparietal diameters (BPD) were determined. For Toggenburg goats the GA = 27.9 + 1.64 BPD; for Nubian goats the GA = 26.8 + 1.74 BPD; for Angora goats the GA = 28.6 + 1.77 BPD. The breed differences in GA for equal BPD are insignificant at the beginning of the second trimester but are +3 d for Nubian and +6 d for Angora fetuses by the end of the second trimester.     

Real-time ultrasonic biparietal diameter of second trimester Suffolk and Finn sheep fetuses and prediction of gestational age

Six Suffolk fetuses of known gestational age were examined every other day from Day 43 to Day 96 of gestation using transabdominal real-time ultrasound. Biparietal diameter (BPD) was measured on symmetrical fetal head images. The relationship between days gestational age (GA) and mean BPD in millimeters is described by the equation: [GA = 22.5 + 1.81 BPD]. Repeated ultrasound examination of 9 Finn ewes between 35 and 95 d of gestation revealed the relationship: [GA = 21.4 + 1.85 BPD]. Biparietal diameters were determined for 56 Suffolk X Hampshire fetuses which ranged from 41 to 77 d of gestation. The predicted fetal age using the Suffolk equation was within 1 d of the recorded age for 22 56 , +/-2 d for 34 56 , and +/-3 d for 44 56 fetuses.     

Ultrasonic biparietal diameter of second trimester Pygmy goat fetuses

Four does pregnant with seven Pygmy goat fetuses were scanned transabdominally from Day 36 to Day 102 of gestation using a real-time ultrasound 5 MHz linear-array scanhead. Fetal biparietal diameter (BPD) was measured on symmetrical frozen images using internal electronic calipers. The relationship between gestational age (GA) in days and BPD in millimeters in Pygmy goat fetuses is expressed as: [GA = 23.2 + 2.08 BPD]. This equation can assign GA to Pygmy goat fetuses of unknown conception dates and allow confinement of does near kidding for induced or observed parturition. Mean kid birthweight was 2.0 + 0.45 kg SEM. These observations are consistent with relationships which have been determined for Toggenburg, Nubian and Angora goat fetuses.     

Real-time ultrasonic biparietal diameter measurement for the prediction of gestational age in llamas

Llama (Lama glama ) fetuses (n = 25) of known gestational age (Day 66 to Day 235) were examined transabdominally using real-time ultrasound with a 5 MHz linear-array scanhead. Maximum head width, or biparietal diameter (BPD), was measured in symmetrical images using electronic linear distance calipers. The fetus was easily located and the BPD measured as early as Day 66 of gestation. During the last trimester, measurement became increasingly difficult due to the posture of the fetus and the limited penetration of the 5 MHz frequency. The relationship between days of gestational age (GA) and mean BPD in millimeters is described by the equation: [GA = 18.8 + 3.79 BPD]. Assignment of gestational age allows estimation of parturition date in this frequently pasture-bred and newly polular domestic ruminant.     

Discrepancy in ultrasound biometric parameters of the head (HC--head circumference, BPD--biparietal diameter) in breech presented fetuses

Background: A comparison of fetal ultrasonographic biometric parameters of the head (head circumference - HC, biparietal diameter - BPD) in breech presented fetuses. Methods: Ultrasound biometry was performed in accordance with the method presented in the reference tables. In all breech presented fetuses, the HC, BPD and FL (femur length) were measured. High-risk and multiple pregnancies were excluded from the study. Results: A total of 111 ultrasonographic biometries were performed between the 31(st) - 38(th) week of gestation. Fetuses in the breech position had a significantly lower BPD compared to HC and FL. The difference between BPD and HC was 16.2 days (95%Cl 14.3-18.1; p = 0.001). Maternal age at delivery was 20 - 36 years (average 28.1; median 28.0). Conclusions: According to our results, fetuses in the breech position have a significantly lower BPD compared to HC or FL. HC and FL parameters correlate with gestational age. In cases of ultrasonographic biometric discrepancy between BPD and FL, the fetal position should be taken into account. Breech-presented fetuses have an elongated head shape and ultrasound biometrics should evaluate its circumference (HC). It is important to responsibly interpret the results so as not to stress the expecting mother with suspicions of fetal pathology.     

Real-time ultrasonic fetal head measurement and gestational age in dairy goats

Dairy breed goat fetuses (n = 219) of known gestational age (Day 39 to Day 100) were examined transabdominally using a real-time ultrasound scanner with a 5 MHz linear-array transducer. Maximum head width was measured in symmetrical images using electronic linear distance calipers. This biparietal diameter (BPD) can be accurately measured as early as Day 40, but measurement becomes difficult after Day 105 of gestation due to the variability of fetal location and posture. The uniform, linear increase in BPD in the second trimester should allow for the accurate assignment of gestational age for doe confinement or induction of kidding.     

Cranial base angulation and prognathism related to cranial and general skeletal maturation in human fetuses.

The purpose of the present study was to describe normal midsagittal craniofacial morphology in second trimester human fetuses. Measurements of the cranial base angle and the prognathism of the maxilla and the mandible were performed on radiographs of cranial midsagittal tissue blocks of 52 fetuses with a gestational age from 13 to 27 weeks. Special procedures were developed for the definitions of the nasion and sella reference points on the radiographs in the early stages of fetal development. Mean data were reported for stages of crown rump length (CRL) and maturation of the fetal cranial base (MSS), usable as reference in assessment of pathological fetal crania in reports and autopsy procedures. Regression equations were determined for the regression of the angular values on CRL, MSS, and general skeletal maturation (TNO). The cranial base angle was found to decrease significantly, and the angles of prognathism to increase significantly with increasing CRL, TNO, and MSS values. It was suggested that these simultaneous and similar changes in the three angles could be accounted for by the upwards movement of the sella point produced by a cranial displacement of the pituitary fossa caused by local cartilagenous growth and bony remodelling during the period of study. The study thus reflects the influence of cranial skeletal maturation on the early development in shape of the craniofacial complex.     

Transvaginal ultrasonographic (TVS) evaluation of baboon gestation from 37–62 days postconception

Our objective was to determine the growth of the embryo and surrounding structures during baboon (Papio anubis) gestation using transvaginal sonography (TVS). To this end, we evaluated 19 timed-mated baboons using TVS between 37 and 62 days of gestation. After visualization of the gestational sac, amniotic sac, and yolk sac, the three largest diameters of each of these extra embryonic structures were measured using longitudinal and transverse views. Embryonic crown–rump length (CRL) was also recorded. Embryonic heart rates were determined using the M-mode function of the ultrasound equipment. All 19 gestations developed without complications. No significant trend could be demonstrated for heart rate or yolk sac diameters over the 37–62 day gestational age period. Mean (SD) gestational age in days, heart rate, and yolk sac diameter, respectively, for the group were 48 (7.8) days (range: 37–61), 180 (15) beats per minute (range: 156–221) and 5 (0.1) mm (range: 3–8). Significant correlations (P < 0.0001) were determined between gestational age and CRL and gestational and amniotic sacs. We conclude that TVS allows a clear visualization of the embryo proper and all the cavities within the gestational sac of the baboon gestation. This study has determined the normal pattern of changes of these cavities from 37–62 days of gestation. Future applications of these findings may include sampling fluid from these cavities for biochemical, cytological, and metabolic studies. Am. J. Primatol. 43:323–328, 1997. © 1997 Wiley-Liss, Inc.     

Skeletal maturation of the human fetus assessed radiographically on the basis of ossification sequences in the hand and foot

In studies of postnatal human development the skeletal maturation of the hand has been found to be a better indicator of general physical maturation than attained body height. For assessment of prenatal human development the Crown-rump length (CRL) has so far been the most commonly used measure. The object of the present study is to examine the possibility of also using the skeletal maturation of the hand as a maturity indicator in fetal development. The study is based upon a radiographic and histochemical investigation of 169 human fetuses. On the basis of counting silver-impregnated diaphyses on radiographs of the hand and foot a maturity indicator (CNO = Composite Number of Ossified bones in hand and foot) was established. Owing to the marked regularity of the recorded ossification pattern, the CNO parameter can be used for evaluating fetal maturation during the early half of the prenatal period. To supplement the assessment of skeletal maturation during the later stages of development, a classification based on the shape of some bones was included in the study. In many cases fetuses of the same size (CRL) exhibited different stages of skeletal maturation (CNO). In accordance with findings from assessment of postnatal development, a more accurate evaluation of fetal development is obtained by combining the size parameter CRL with an assessment of fetal skeletal maturation, CNO.     

Ultrasonographic fetometry and determination of fetal sex in buffaloes (Bubalus bubalis)

The aim of the current study was to establish ultrasonic biometric threshold of different fetal parts in buffaloes and to evaluate the feasibility and accuracy of ultrasonic fetal sex determination. Serial ultrasonographic examinations were carried out on twelve pregnant buffalo-cows, during which fetal parts were measured, and fetal sex and presentation were determined. The obtained results revealed that embryo and amniotic vesicle (AV) were detected by the forth and fifth week of pregnancy, respectively. Organization was observed by the seventh week, while ossification was indicated between the eighth and 10th week. High correlations were found between different studied parameters and gestational age, where the highest correlation was found with the crown-rump length (CRL) and amniotic vesicle diameter (AVD) at the early-gestation; the biparietal diameter (BPD) at the mid-gestation; and the eyeball diameter (EBD) at the mid- and late-gestation. The results also revealed that the best window for fetal sexing was found between the 10th and 18th week of gestations, with an overall accuracy of 97.1%. The final polarity with all fetuses in anterior presentation was adopted by the 30th week. In conclusion, the overall data indicated the feasibility and value of ultrasonographic fetometry in buffaloes for evaluation of fetal development, estimation of gestational age and determination of fetal sex.     

Ultrasonic assessment of pregnancy and fetal development in three species of macaque monkeys

Serial ultrasonic assessments of gestational sac (GS) and fetal biparietal diameter (BPD) were performed in the Japanese monkey (Macaca fuscata fuscata), rhesus monkey (Macaca mulatta), and crab-eating monkey (Macaca fascicularis). In the Japanese monkey, GS increased linearly for 3-8 weeks, whereas BPD increased in a linear-quadratic manner over 8 weeks to term. Ultrasonic assessments of spontaneously aborted fetuses with BPD growth retardation and diagnosis of a pelvic chocolate cyst also were reported.     

Plasma 11-deoxycorticosterone (DOC) and mineralocorticoid receptor testicular expression during rainbow trout Oncorhynchus mykiss spermiation: implication with 17alpha, 20beta-dihydroxyprogesterone on the milt fluidity?

Background

Non-invasive micro-ultrasound was evaluated as a method to quantify intrauterine growth phenotypes in mice. Improved methods are required to accelerate research using genetically-altered mice to investigate the interactive roles of genes and environments on embryonic and placental growth. We determined (1) feasible age ranges for measuring specific variables, (2) normative growth curves, (3) accuracy of ultrasound measurements in comparison with light microscopy, and (4) weight prediction equations using regression analysis for CD-1 mice and evaluated their accuracy when applied to other mouse strains.

Methods

We used 30–40 MHz ultrasound to quantify embryonic and placental morphometry in isoflurane-anesthetized pregnant CD-1 mice from embryonic day 7.5 (E7.5) to E18.5 (full-term), and for C57Bl/6J, B6CBAF1, and hIGFBP1 pregnant transgenic mice at E17.5.

Results

Gestational sac dimension provided the earliest measure of conceptus size. Sac dimension derived using regression analysis increased from 0.84 mm at E7.5 to 6.44 mm at E11.5 when it was discontinued. The earliest measurement of embryo size was crown-rump length (CRL) which increased from 1.88 mm at E8.5 to 16.22 mm at E16.5 after which it exceeded the field of view. From E10.5 to E18.5 (full term), progressive increases were observed in embryonic biparietal diameter (BPD) (0.79 mm to 7.55 mm at E18.5), abdominal circumference (AC) (4.91 mm to 26.56 mm), and eye lens diameter (0.20 mm to 0.93 mm). Ossified femur length was measureable from E15.5 (1.06 mm) and increased linearly to 2.23 mm at E18.5. In contrast, placental diameter (PD) and placental thickness (PT) increased from E10.5 to E14.5 then remained constant to term in accord with placental weight. Ultrasound and light microscopy measurements agreed with no significant bias and a discrepancy of less than 25%. Regression equations predicting gestational age from individual variables, and embryonic weight (BW) from CRL, BPD, and AC were obtained. The prediction equation BW = -0.757 + 0.0453 (CRL) + 0.0334 (AC) derived from CD-1 data predicted embryonic weights at E17.5 in three other strains of mice with a mean discrepancy of less than 16%.

Conclusion

Micro-ultrasound provides a feasible tool for in vivo morphometric quantification of embryonic and placental growth parameters in mice and for estimation of embryonic gestational age and/or body weight in utero.     

Integrating ultrasonography within the reproductive management of the collared peccary (Tayassu tajacu)

Ultrasound imaging has been used to elucidate certain aspects of the reproductive biology of wild or endangered species. However, to our knowledge, this tool has not been used for reproductive monitoring of the collared peccary (Tayassu tajacu). In this study, real-time ultrasonography was used in 16 collared peccary females to diagnose early pregnancy status and predict gestational age. Based on the detection of an embryo, the earliest pregnancy diagnosis was made on Day 18 after mating, with the mean time needed for diagnosis being 22 days. Overall accuracies on Days 22, 26 and 28 were 56, 93, and 100%, respectively. On Days 26 and 28, all pregnancy and non-pregnancy diagnoses, respectively, were correct. The fetal measurements that best correlated with gestational age were crown-rump-length (CRL) and the length and diameter of the thorax. CRL was considered the most practical measurement because, contrary to thoracic fetometry, it could be determined when the embryo was first detected. Our findings revealed real-time ultrasound scanning to be a very accurate method for early pregnancy diagnosis and prediction of gestational age in the collared peccary.     

The influence of prenatal and postnatal fraternity size on reproduction in mice

Effects of prenatal and postnatal fraternity size (size of litter in which an individual is reared) on age at vaginal opening, growth, and subsequent litter production were examined by rearing mice in standardized prenatal and postnatal fraternities in a 3 X 3 factorial design. Prenatal fraternity size was standardized by reducing litters of 14 or more to either 14, 10, or 6 fetuses on Day 9 of gestation. Postnatal fraternity size was standardized by assigning pups randomly to nurse in litters of 5, 10, or 15 pups within 24 h of birth. Both prenatal and postnatal fraternity size affected growth of the mice (p = 0.02 and p less than 0.01, respectively) with mice reared in small fraternities attaining greater weights throughout the study. Prenatal fraternity size had a negative linear effect on litter size at second parity and tended to have a positive linear effect on age at vaginal opening. Postnatal fraternity size affected age at vaginal opening (p less than 0.01), litter size at first parity (p less than 0.01), and litter size at second parity (p = 0.03). These effects were positive and linear for age at vaginal opening (p less than 0.01; small fraternity size associated with younger age at vaginal opening) and negative and linear for litter size at first and second parity (p less than 0.01 and p = 0.10, respectively; smaller fraternity size associated with larger litter size). There was no interaction between prenatal and postnatal fraternity size effects on age at vaginal opening or litter size (p greater than 0.20).     

Reproductive efficiency in the common marmoset (Callithrix jacchus): A longitudinal study from ovulation to birth monitored by ultrasonography

Abstract: This study examines reproductive efficiency in the common marmoset monkey, Callithrix jacchus, using sequential ultrasound examinations to establish ovulation number, implantation rate, and incidence of prenatal loss. Ultrasound was carried out with a 10 or 7.5 mHz probe in nonsedated animals, daily during the late follicular phase, approximately twice a week until day 20 after ovulation, and at days 35, 56, and 85 of pregnancy to enable visualization of gestation sacs, heartbeats, and fetal heads, respectively. Ovulatory follicles could be seen 3–4 days before ovulation and by day –2, 98% of ovulating follicles were >2mm diameter, although almost 10% of follicles of this size disappeared without ovulating. Total number of ovulating follicles for 15 females was 45 (mean ovulation rate ? 3.0, range 2–4). In the 14 animals that conceived, 41 corpora lutea were identified (mean ovulation rate = 2.9) within 10 days of ovulation. All pregnancies went to term (no abortion occurred) resulting in the birth of 37 neonates (9 triplets, 5 twins) and an average litter size of 2.64. All four losses were confined to the embryonic period (< day 85), two occurring before day 35, one between days 35 and 56, and one between days 56 and 85. In demonstrating that 90% of ovulatory follicles gave rise to live offspring, the results of this study indicate an extremely high reproductive efficiency in the marmoset monkey (when maintained under favorable captive conditions) and a rate of prenatal loss much lower than that reported for other primate species.