Ultrastructure of the pronephric kidney of embryos and prolarvae of the sea lamprey, Petromyzon marinus

Embryos of lampreys Petromyzon marinus were obtained through a technique of artificial fertilization. Samples of developmental intervals to the prolarval stage were prepared for transmission electron microscopy and the pronephros was examined. The pronephros was visible in the cardiac region of the coelom prior to the time of hatching of embryos and consisted of a renal corpuscle, nephrostomes, and proximal tubules connected to a pronephric duct. The renal corpuscle was comprised of poorly-defined vascular channels and a visceral epithelium of yolk-filled cells, the podocytes, with short major processes and pedicels resting on a basal lamina. The first proximal tubules possessed a delicate brush border of short microvilli but subsequent cellular differentiation yielded cells with all the components required for the process of endocytosis, a process which was demonstrated by uptake of the tracer, horseradish peroxidase. The distal tubules appeared later in development and were noted for abundant mitochondria and an extensive smooth tubular network. The timing of differentiation of various components of the nephron corresponds to that seen during morphogenesis of other vertebrate kidneys.     

Fine structure of the spermatozoon of the strepsipteran Xenos moutoni

Spermatozoa of Xenos moutoni De Buysson belonging to the order Strepsiptera (Insecta) were examined by electron microscopy. The spermatozoon was seen to have an elongated head and a tail containing a 9+9+2 axoneme and two mitochondrial derivatives of equal size. The pear-shaped acrosome is characterised by a mono-layered structure and terminates anteriorly forming two pyramidal evaginations. The nucleus exhibits an external portion of dense chromatin and an internal one of uncondensed material. The latter occupies a central position at the base and becomes progressively peripheral at the apex. The tail is long and in its final portion the axoneme loses its elements progressively. These results have been compared with the ultrastructure of the spermatozoa of Coleoptera which have been considered as a sister group of Strepsiptera.     

Quantity and quality of embryos collected from mice passively immunized against estradiol

The objective of this study was to determine the effects of passive immunization against estradiol on the occurrence and timing of estrus, ovulation and fertilization rates and on early embryonic development in mice. Swiss Webster fermale mice were randomly assigned to one of the three treatment groups to be injected with 0.1 ml saline (control; n=15), 0.1 ml anti-estradiol antisera (high dose: n=17) or 0.1 ml antiestradiol antisera diluted 1:10 with saline (low dose; n=17) at seven weeks of age. Immediately after injection mice were placed with males and observed daily for the presence of vaginal plugs for 10 d. Three days after vaginal plugs were observed, mice were terminated and the uteri were removed and flushed to determine the number and quality of unfertilized ova and embryos. No differences were observed in the timing of vaginal plug formation, the proportion of mice with vaginal plugs, or the mean number of unfertilized ova or embryos collected from each treatment group. However, the proportion of excellent or good quality embryos was reduced in the high dosage treatment. It was concluded from this study that passive immunization of mice against estradiol did not increase the number of embryos obtained from mice and that a high dosage of antisera against estradiol reduced embryo quality. These results provide evidence that alterations in levels of estradiol may adversely affect embryonic development.     

Effects of dietary energy level on luteinizing hormone and adrenal function in the post partum beef cow

The effects of dietary energy and suckling on adrenal function and luteinizing hormone (LH) concentrations were investigated in primiparous postpartum cows. Ten heifers were assigned at calving to either high (22.8 Mcal/day) or low (15.2 Mcal/day) energy diets. Blood samples were collected every 15 minutes for 8 hours on 28, 42, and 56 days post partum. Calves were allowed to suckle ad libitum during sampling periods. Serum samples were analyzed by radioimmunoassay for LH and cortisol. Concentrations of catecholamines were quantified by reverse-phase HPLC. Body weights were decreased (P<0.01) by low energy intake. In addition, low energy diet cows had lower mean LH concentrations (0.97 +/- 0.09 vs 1.57 +/- 0.07 ng/ml), P<0.05) than high energy diet cows. Luteinizing hormone concentrations in high energy diet cows increased with days post partum, resulting in a treatment-by-time interaction (P<0.005). Treatment did not affect mean cortisol concentrations. However, within 15 minutes of suckling cortisol release was significantly above baseline in 77% of the observed suckling events. Dihydroxyphenylalanine (DOPA) increased in high energy diet cows compared with that of low energy diet cows (2,833 +/- 243 vs 1,294 +/- 243 pg/ml, P<0.01). Norepinephrine (NE) and 3,4-dihydroxyphenylacetic acid (DOPAC) were not influenced by treatment. Plasma NE decreased during the postpartum interval (P<0.005). These data suggest that reduced energy intake may prevent the increase in LH associated with increasing days post partum and alter adrenal function. In addition, spontaneous suckling events elicit a release of cortisol.     

Are antibodies responsible for a decreased superovulatory response in goats which have been treated repeatedly with porcine follicle-stimulating hormone?

Repeated administration of xenogenic gonadotropins in human or animal species may be responsible for antibody production and refractoriness. An experiment was conducted in which goats were treated with porcine FSH (p-FSH) at 6-week intervals for a period of 7 months. A sensitive radioimmunoassay (RIA) was used to detect antibodies to p-FSH in plasma samples taken at short-term intervals during a 7-month period. Antibodies appeared after the first injection, and levels increased following booster injections. A high correlation rate existed between antibody level and superovulatory response. Refractoriness in goats was associated with a high level of antibodies.     

Ovarian function and pregnancy rates in reindeer calves (Rangifer tarandus ) in Southern Norway

Reindeer calves (n = 632) were slaughtered in November/December (n = 476) or in January (n = 156). Dressed weights and amount of perirenal fat were recorded, and the reproductive organs were collected. A separate group of 130 reindeer calves were weighed at 7 months of age and were followed up with repeated weighings and pregnancy examinations up to 21 months. The onset of puberty and the pregnancy rate were significantly influenced by body weight and the amount of perirenal fat. Approximately 60 g of perirenal fat and 22 kg dressed weight were found at the lower limits for pregnancy. A total of 222 (35%) animals had reached puberty and 126 (20%) were pregnant when examined after slaughter. Animals which conceived during their first autumn showed only a moderate weight gain the following year, and the calf mortality rate in these animals was 47.4%. It was concluded that calf pregnancies are common among the reindeer of Southern Norway and that measures need to be taken to prevent them.     

Frozen bovine semen quality and bovine cervical mucus penetration test

Research has been carried out to test bovine cervical mucus penetration (penetration) as a means for evaluating frozen-thawed bovine semen. A commercially available cervical mucus penetration test kit (the kit) was used. A total of 158 previously frozen semen samples collected from 61 bulls were thawed in a 37 C water-bath for 2 minutes. Four ways to estimate penetration were compared using the distance traveled during 90 minutes 1) at 21 C, or 2) at 37 C, by 3) the first solitary mobile spermatozoon, or by 4) the front of the mass of the mobile spermatozoa. Penetration was measured using phase contrast microscopy and a millimeter grid. Spermatozoal quality parameters (concentration, total motility, progressive motility, acrosome integrity, total sperm integrity and cytoplasmic droplets) were measured and the correlation to penetration was calculated. The best way to assay penetration with the kit was by measuring the penetration of the first solitary mobile spermatozoon at 37 C. Semen quality variability was significant (P < 0.05) relative to penetration. Linear correlations between penetration and acrosome integrity r=0.42 as well as between penetration and total sperm integrity r=0.53 were highly significant (P < 0.001). There was significant linear multiple regression between penetration and acrosome integrity (expressed as percentage and number) and total sperm integrity (expressed as percentage and number) (r=0.62; F=23.5147; P<0.0001). There was a significant difference between the average progressive motility of samples with penetration > 20 mm and samples with penetration 20%), but it is not useful to define the fertility level of semen samples.     

In vitro development of day-2 equine embryos co-cultured with oviductal explants or trophoblastic vesicles

This study compared the in vitro development of Day-2 equine embryos co-cultured with either trophoblastic vesicles or oviductal explants. Embryos were collected surgically from the oviducts of pony mares 2 d after ovulation and assessed for stage of development. Culture medium was Ham's F12 and Dulbecco's Modified Eagle's Medium (50:50 v/v) in a humidified atmosphere of 5% CO(2) in air at 38.5 degrees C with either trophoblastic vesicles or oviductal explants. The quality score of embryos was assessed daily. After 4 d in culture, embryos were stained (Hoechst 33342) and evaluated with epifluorescence to determine the number of nuclei present. Six of seven embryos co-cultured with oviductal exmplants developed to the morula/blastocyst stage, while four of seven embryos co-cultured with trophoblastic vesicles developed to the morula stage. More (P = 0.1) embryos co-cultured with oviductal explants reached the blastocyst stage than embryos co-cultured with trophoblastic vesicles (3 7 vs 0 7 , respectively). The number of cells was higher (P = 0.1) for embryos co-cultured with oviductal explants than for embryos co-cultured with trophoblastic vesicles (162.6 +/- 32 vs 87.3 +/- 28, respectively). The number of cells for embryos co-cultured with either oviductal explants or trophoblastic vesicles appeared to be lower than for embryos matured in vivo that were recovered from the uterus at Day 6 (378, 399, >1000). The co-culture of early equine embryos in a completely defined medium with either trophoblastic vesicles or oviductal explants can support development to at least the morula stage. The co-culture of embryos with oviductal explants resulted in superior development of four-to eight-cell embryos, as indicated by the proportion that reached the blastocyst stage and by the number of cells.     

Effect of nutrition and endoparasitic treatment on growth, onset of puberty and reproductive activity in Menz ewe lambs

Ewe lambs of the Ethiopian Menz breed were assigned at weaning (90+/-3 days) to four levels of nutrition (poor, low, medium and high) to achieve different premating growth rates with or without treatment for endoparasites. A concentrate mixture providing 2.5 Mcal/kg dry matter (DM) metabolizable energy and 15.2 g/kg DM digestible protein was used. Improved nutrition increased lamb postweaning average daily weight gain up to puberty by 6 to 26 g/day and the conception rate to first estrus by 9 to 16% while it reduced the mortality rate by 24 to 31% and age at first lambing by 2 to 5 months. Lambs reached puberty (age at first estrus) at 16.9+/-0.1 kg (+/-SEM) or 60% of mature body weight and 350+/-12 days of age. The onset of puberty was advanced by weaning weight (P<0.05), itself being well correlated with birth weight (r = 0.51, P<0.001), and by level of nutrition (high=299+/-19, medium=301+/-18, low=383+/-23 and poor=454+/-31 days, P<0.001) through enhanced growth rate (r = -0.82, P<0.001). No independent effect of drenching for endoparasites on pubertal development was observed (P>0.05), but its interaction with season-of-birth improved the growth of lambs born during the period of short rains (P<0.05). Overall mean litter size at first lambing was 1.07; the twinning rate was 6.5% and the birth weight was 1.9+/-0.1 kg. Up to 13.4% of newborn lambs, averaging 1.3+/-0.6 kg, died on the day of parturition. The results indicate that improved growth rate and body weight, resulting from better postweaning nutrition, affects the attainment of puberty in Menz ewe lambs. Mitigation of nutrition stress and endoparasitic infection depending on season-of-birth would thus increase the annual reproductive rate of breeding ewes and flock productivity.     

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.