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Biomedical subjects

D Smidt

Publications and source records attributed to D Smidt.

At least 55 records · Page 3Linked to original sources
PubMed1977

Uterine position and presentation of minipig-fetuses and their order and presentation at birth.

Uterine position and presentation of fetuses in 17 minipigs during pregnancy were compared with their order and presentation at birth. Fetuses from 1 or both uterine horns were marked between day 80 and day 105 of gestation by 1 or more transuterine injections of either a 2.5% solution of dianil blue (3 animals) or a radiopaque substance (14 animals). Roentgenograms of the newborn pigs, which were ear-notched immediately after birth, enabled making individual identification. Pigs seemed to be delivered randomly from the 2 uterine horns. They either followed a neighbor from the same horn (n = 42) or followed a pig from the contralateral horn (n = 52). Only in 3 dams did 1 uterine horn become empty before delivery from the other horn started. In 4 dams, 1 pig passed its neighbor from the same horn, thereby being born earlier than expected. Moreover, passing of pigs could have occurred and gone undetected in those dams from which the pigs of only 1 horn were marked. This passing might have taken place within the uterine body. From 18 of 95 pigs (19%) , the presentation at birth differed from the one observed at laparotomy.

Animals↗
PubMed1976

Plasma luteinizing hormone and progesterone in the adult female pig during the oestrous cycles, late pregnancy and lactation, and after ovariectomy and pentobarbitone treatment.

In a series of experiments on female miniature pigs, the pattern of plasma LH and progesterone levels during the oestrous cycle, late pregnancy and lactation and after ovariectomy were characterized, and the effect of pentobarbitone treatment was tested. The preovulatory surge of LH occurred in seven out of eight animals between 00.00 and 12.0 h on day 0 of the oestrous cycle (day 1 of standing heat). Plasma progesterone strated to decline 8 days before oestrus and reached its lowest value 5 days before the preovulatory LH peak. Increases in progesteron concentration were already noticeable 48 h after the LH surge. During late pregnancy, parturition and lactation, plasma LH was low and showed only minor fluctuations, while plasma progesterone declined 4 to 5 days before parturition. Both hormones remained at low levels throughout lactation. Three weeks before parturition increases in LH were always followed by an increase in progesterone. This dependency was greatly diminished immediately before delivery. Four to 12 days after weaning the animals came into oestrus which was followed by an increase in LH and later an increase in progesterone concentrations. Ovariectomy during dioestrus resulted in a steady increase in plasma LH levels of 35-39 days. Ovariectomy caused abortion if performed on day 100 of pregnancy. It was followed by a rapid increase of plasma LH concentration. Normal parturition (around day 115) and lactation took place when animals were spayed on day 112 of pregnancy. In this case, plasma LH levels remained even lower than before ovariectomy as long as lactation was maintained. Immediately after weaning a rapid increase in the normal postovariectomy pattern of LH secretion was observed. Pentobarbitone anaesthesia (30-35 mg/kg body wt, initial dose), during pro-oestrusoestrus, for less than 5 h had no effect on the preovulatory LH increase. However, pentobarbitone anaesthesia for more than 6 h inhibitied the LH peak and ovulation if the animal was under deep anaesthesia before 24.00 h on the day before oestrus. Pentobarbitone treatment of ovariectomized pigs resulted in a clear decrease in LH levels 40 min after a single i.v. dose.

Animals↗